From 81367a36bb433b6f5beb2dcb65c807372c301f38 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 08:10:07 +0530
Subject: [PATCH 01/37] jenkins env 09-May-22

---
 pipeline/Jenkinsfile | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index 22e3b78..d455d19 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -2,12 +2,19 @@ pipeline {
     
 	agent { label 'slave2' } 
     
+	environment {
+		TEST = "pipeline_level"
+	}
+	
 	stages {
 			
 			stage('Build') {
+				environment {
+					TEST = "stage_level"
+				}
 				steps {
 					sh ''' 
-							echo "STAGE 1: This is a build stage"
+							echo "STAGE 1: This is a build stage $TEST"
 							sleep 5
 					   '''
 				}
@@ -19,7 +26,7 @@ pipeline {
 					stage('Test') { 
 						steps {
 							sh '''
-								   echo "STAGE 2: This is a Test stage"
+								   echo "STAGE 2: This is a Test stage $TEST"
 								   sleep 5
 							   ''' 
 						}
@@ -28,7 +35,7 @@ pipeline {
 					stage('Deploy') { 
 						steps {
 							sh ''' 
-									echo "STAGE 3: This is a Deploy stage"
+									echo "STAGE 3: This is a Deploy stage $TEST"
 									sleep 5
 							   '''
 						}

From 25de063d0f6a0725998afff12569d374f129f2af Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 08:14:47 +0530
Subject: [PATCH 02/37] jenkins env 09-May-22

---
 pipeline/Jenkinsfile | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index d455d19..dacbc6a 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -21,8 +21,12 @@ pipeline {
 			}
 					
 			stage('Test and Deploy') { 
+				
+				input {
+					message 'Press yes to continue'
+				}
+				
 				parallel {
-					
 					stage('Test') { 
 						steps {
 							sh '''

From be555e35ae1374df395d4fa0a427d361f6a73d34 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 08:25:38 +0530
Subject: [PATCH 03/37] jenkins parameters 09-May-22

---
 pipeline/Jenkinsfile | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index dacbc6a..0bfd176 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -2,16 +2,16 @@ pipeline {
     
 	agent { label 'slave2' } 
     
-	environment {
-		TEST = "pipeline_level"
-	}
 	
+	parameters {
+	  string defaultValue: 'test', description: 'Which environment should the build need to deployed', name: 'TEST', trim: true
+	}
+
+
 	stages {
 			
 			stage('Build') {
-				environment {
-					TEST = "stage_level"
-				}
+			
 				steps {
 					sh ''' 
 							echo "STAGE 1: This is a build stage $TEST"

From d12eed4205cf1f886dc7c1a435e580d77fbb7ed0 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 08:34:41 +0530
Subject: [PATCH 04/37] jenkins catchError 09-May-22

---
 jenkins.txt          |  3 ++-
 pipeline/Jenkinsfile | 23 +++++++----------------
 2 files changed, 9 insertions(+), 17 deletions(-)

diff --git a/jenkins.txt b/jenkins.txt
index 2a0e7bb..afba352 100644
--- a/jenkins.txt
+++ b/jenkins.txt
@@ -67,4 +67,5 @@ Agent
 			  on a perticular node with label.
 			  
 		docker 
-			
\ No newline at end of file
+			
+Build should not fail if a stage fails.			
\ No newline at end of file
diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index 0bfd176..71c0b21 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -1,36 +1,27 @@
 pipeline {
     
 	agent { label 'slave2' } 
-    
-	
-	parameters {
-	  string defaultValue: 'test', description: 'Which environment should the build need to deployed', name: 'TEST', trim: true
-	}
-
 
 	stages {
 			
 			stage('Build') {
 			
 				steps {
-					sh ''' 
-							echo "STAGE 1: This is a build stage $TEST"
-							sleep 5
-					   '''
+					catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
+						sh ''' 
+								exit 0
+						   '''
+					}	   
 				}
 			}
 					
 			stage('Test and Deploy') { 
 				
-				input {
-					message 'Press yes to continue'
-				}
-				
 				parallel {
 					stage('Test') { 
 						steps {
 							sh '''
-								   echo "STAGE 2: This is a Test stage $TEST"
+								   echo "STAGE 2: This is a Test stage"
 								   sleep 5
 							   ''' 
 						}
@@ -39,7 +30,7 @@ pipeline {
 					stage('Deploy') { 
 						steps {
 							sh ''' 
-									echo "STAGE 3: This is a Deploy stage $TEST"
+									echo "STAGE 3: This is a Deploy stage"
 									sleep 5
 							   '''
 						}

From e263658a1d5c28d16b726fcb71187142ef033979 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 08:39:35 +0530
Subject: [PATCH 05/37] jenkins when condition 09-May-22

---
 pipeline/Jenkinsfile | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index 71c0b21..27890b4 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -5,7 +5,9 @@ pipeline {
 	stages {
 			
 			stage('Build') {
-			
+				when {
+					branch 'release*'
+				}
 				steps {
 					catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
 						sh ''' 

From 67a7050d7e7d2d79447a9d88ed641588ac4b6717 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 08:43:18 +0530
Subject: [PATCH 06/37] jenkins if condition 09-May-22

---
 pipeline/Jenkinsfile | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index 27890b4..71002f5 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -5,15 +5,14 @@ pipeline {
 	stages {
 			
 			stage('Build') {
-				when {
-					branch 'release*'
-				}
-				steps {
-					catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
-						sh ''' 
-								exit 0
-						   '''
-					}	   
+				if (env.BRANCH_NAME == "release*" ) {
+					steps {
+						catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
+							sh ''' 
+									exit 0
+							   '''
+						}	   
+					}
 				}
 			}
 					
@@ -23,7 +22,7 @@ pipeline {
 					stage('Test') { 
 						steps {
 							sh '''
-								   echo "STAGE 2: This is a Test stage"
+								   echo "$NODE_NAME -> $JOB_NAME -> $BUILD_NUMBER "
 								   sleep 5
 							   ''' 
 						}

From 2d1a58a0640a92ac59109b6a285d38fda1d9b4e6 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 08:44:16 +0530
Subject: [PATCH 07/37] jenkins if condition 09-May-22

---
 pipeline/Jenkinsfile | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index 71002f5..1b49ae7 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -5,13 +5,14 @@ pipeline {
 	stages {
 			
 			stage('Build') {
-				if (env.BRANCH_NAME == "release*" ) {
-					steps {
-						catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
-							sh ''' 
-									exit 0
-							   '''
-						}	   
+				steps {
+					if (env.BRANCH_NAME == "release*" ) {
+						
+							catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
+								sh ''' 
+										exit 0
+								   '''
+							}	   
 					}
 				}
 			}

From 6db032bc45731b6cbe6d120e8adb77318615317f Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 08:45:13 +0530
Subject: [PATCH 08/37] jenkins if condition 09-May-22

---
 pipeline/Jenkinsfile | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index 1b49ae7..acae017 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -5,16 +5,16 @@ pipeline {
 	stages {
 			
 			stage('Build') {
-				steps {
-					if (env.BRANCH_NAME == "release*" ) {
-						
-							catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
-								sh ''' 
-										exit 0
-								   '''
-							}	   
-					}
+				when {
+					branch 'main'
 				}
+					steps {
+						catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
+							sh ''' 
+									exit 0
+							   '''
+						}	   
+					}
 			}
 					
 			stage('Test and Deploy') { 

From ae8944c503ab4939eb1eb968ca5e6c2a40f6d3eb Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 09:13:21 +0530
Subject: [PATCH 09/37] jenkins shared lib 09-May-22

---
 jenkins.txt          | 23 ++++++++++++++++++++++-
 pipeline/Jenkinsfile |  6 +++++-
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/jenkins.txt b/jenkins.txt
index afba352..46243c2 100644
--- a/jenkins.txt
+++ b/jenkins.txt
@@ -68,4 +68,25 @@ Agent
 			  
 		docker 
 			
-Build should not fail if a stage fails.			
\ No newline at end of file
+Build should not fail if a stage fails.		
+	use catchError for this requirement
+
+		stage('Build') {
+			steps {
+				catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
+					sh ''' 
+							exit 0
+					   '''
+				}	   
+			}
+		}	
+		
+Jenkins shared library set-up 
+	STEP 1: Create a git repo (To keep our groovy scripts and it is called as shared library)
+	STEP 2: Create a folder by name "vars" in the root of your repo.
+	STEP 3: Create a script with .groovy type (getUser.groovy).
+	STEP 4: configure jenkins to attach the above library.
+				Manage Jenkins -> Configure system -> Global Pipeline Libraries
+					Add ->  Name - give any name 
+							Default Version - Branch in which vars is there
+							Retrieval method - Modern SCM 
\ No newline at end of file
diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index acae017..a49d87b 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -1,6 +1,10 @@
 pipeline {
     
 	agent { label 'slave2' } 
+	
+	libraries {
+		lib('printuser@main')
+	}
 
 	stages {
 			
@@ -11,7 +15,7 @@ pipeline {
 					steps {
 						catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
 							sh ''' 
-									exit 0
+									getUser 'Harsha' 'Trainee'
 							   '''
 						}	   
 					}

From 6f583e2d2326068e97cae6a522938ff0875849ff Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 09:14:18 +0530
Subject: [PATCH 10/37] jenkins shared lib 09-May-22

---
 pipeline/Jenkinsfile | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index a49d87b..438bee3 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -9,9 +9,6 @@ pipeline {
 	stages {
 			
 			stage('Build') {
-				when {
-					branch 'main'
-				}
 					steps {
 						catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
 							sh ''' 

From ad837bb373d003d5b1047df0e0bb0f970d153fd9 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 09:14:54 +0530
Subject: [PATCH 11/37] jenkins shared lib 09-May-22

---
 pipeline/Jenkinsfile | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index 438bee3..c4b0723 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -11,9 +11,7 @@ pipeline {
 			stage('Build') {
 					steps {
 						catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
-							sh ''' 
-									getUser 'Harsha' 'Trainee'
-							   '''
+							getUser 'Harsha' 'Trainee'
 						}	   
 					}
 			}

From 16f1a5cb0ad8e2931b70a4d6ec1faf1811d0942b Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 09:16:37 +0530
Subject: [PATCH 12/37] jenkins shared lib 09-May-22

---
 pipeline/Jenkinsfile | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index c4b0723..02ed6a5 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -1,17 +1,19 @@
+@Library('printuser')_
+
+getUser 'Harsha' 'Trainee'
+
 pipeline {
     
 	agent { label 'slave2' } 
 	
-	libraries {
-		lib('printuser@main')
-	}
+
 
 	stages {
 			
 			stage('Build') {
 					steps {
 						catchError(buildResult: 'SUCCESS', stageResult: 'FAILURE') {	
-							getUser 'Harsha' 'Trainee'
+							sh 'echo "STAGE 1 this is build stage"'
 						}	   
 					}
 			}

From 4f73b34d59ee6a1a3ddaa253fe9b2a62a92e00db Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 09:20:26 +0530
Subject: [PATCH 13/37] jenkins shared lib 09-May-22

---
 pipeline/Jenkinsfile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pipeline/Jenkinsfile b/pipeline/Jenkinsfile
index 02ed6a5..1ad5725 100644
--- a/pipeline/Jenkinsfile
+++ b/pipeline/Jenkinsfile
@@ -1,6 +1,6 @@
 @Library('printuser')_
 
-getUser 'Harsha' 'Trainee'
+getUser 'Harsha', 'Trainee'
 
 pipeline {
     

From 11eaa3d5d16dcfe39862db70cf671678fd70c2d4 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 09:24:13 +0530
Subject: [PATCH 14/37] jenkins shared lib 09-May-22

---
 jenkins.txt | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/jenkins.txt b/jenkins.txt
index 46243c2..f5c02d2 100644
--- a/jenkins.txt
+++ b/jenkins.txt
@@ -87,6 +87,11 @@ Jenkins shared library set-up
 	STEP 3: Create a script with .groovy type (getUser.groovy).
 	STEP 4: configure jenkins to attach the above library.
 				Manage Jenkins -> Configure system -> Global Pipeline Libraries
-					Add ->  Name - give any name 
+					Add ->  Name - give any name (<library_name>)
 							Default Version - Branch in which vars is there
-							Retrieval method - Modern SCM 
\ No newline at end of file
+							Retrieval method - Modern SCM 
+	STEP 5: In any pipeline job import the library using @Library directive 
+				@Library('<library_name>')_
+				
+				// Then call the script by its name (getUser.groovy)
+					getUser '<username>', '<designation>'
\ No newline at end of file

From faa8e06915b075966a23dc12ae732439f2419fb6 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 9 May 2022 10:33:41 +0530
Subject: [PATCH 15/37] maven 09-May-22

---
 maven.txt | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 maven.txt

diff --git a/maven.txt b/maven.txt
new file mode 100644
index 0000000..33c9ea8
--- /dev/null
+++ b/maven.txt
@@ -0,0 +1,94 @@
+Maven is a project management tool which can manage complete build lifecycle.
+Maven simplifies and standardizes the project build process.
+
+Build process will be 
+	compile
+	testing 
+	library dependency 
+	distribution 
+	documentation 
+	deployment 
+	
+POM.xml 
+	- project object modal 
+	- In this file we put all the maven configurations.
+
+Maven folder structure 
+├── pom.xml
+└── src
+    └── main
+        ├── java
+        │   └── com
+        │       └── yourorganization
+        │           └── maven_sample
+        │               └── LogicPositivizer.java
+        └── resources
+            └── Blabla.java
+└── target	
+
+Maven build life cycle 
+A build lifecyle is a sequence of task used to build the application.
+	1. validate - validate thr project is correct and all the necessary information is 	  
+	              available. 		
+	2. compile - compiles the source code and create obeject code in target folder.
+	3. Test    - Test the compiled source code using unit testing (JUnit)
+	4. Package - All the compiled code is packages in to distribution format which is jar, war  
+	             and ear.	
+    5. integration-test - deplpy the package/build/artifact into an environment where 
+	                      integration-test can be executed  
+    6. verify  - verify the package is valid and it meets the configured criteria or not.
+	7. install - install/copy the package into the local repository.
+    8. deploy  - If configured, deploy the application/build to integration or relese environment.
+	
+Maven repository
+	Maven repository is a directory to store all the project jars, libraries, plugins and any artifacts related to project.	
+		1. Local Repository
+			- Is a local folder/directory on your machine (where we have installed or running 
+			  maven)
+			- The default location of maven local repository is HOME_DIRECTORY/.m2 directory
+			- .m2 is created when ever we run mvn command for the first time.
+			
+		2. Central Repository
+			- Maven central repository is managed by maven community and it contains large number 
+			  commonly used libraries.
+			- We can also publish our own libraries to central repository.
+		    - The default location is https://repo1.maven.org/maven2			
+			
+		3. Remote Repository
+			- A maven repository setup inside a company or a project related repository but not   
+			  public.
+			- This is a company maintained reposiroty which can be accessed only inside the 	  
+			  company network.
+	
+Maven dependency Search sequence 
+	1. Search in local repo.
+	2. Search in central repo.
+    3. Search in remote repo.
+
+	Maven stops searching once it finds the library.	
+	
+groupId
+	Is the unique project name or organization name 
+		- org (organization) 
+		- com (commercial) 
+			- company name 
+				- project/module
+artifactId
+	IS the name of the project / name of build 
+	
+versionId
+	Is the version number of the project 
+	
+properties 
+	- To set default encoding type 
+	- To set the maven version 
+
+Difference bertween mvn install vs mvn deploy 
+	install - it will upload the artifact to local repository (.m2 folder)
+	deploy - uploads the package/artifact to the another/remote repository 	
+		
+Assignment 
+	what is maven site ?
+	Check and run Archetype 
+	How to integrate maven with tomcat ?
+	
\ No newline at end of file

From 5ef1e310c041763532984e4b27297e86d439c820 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Tue, 10 May 2022 11:06:04 +0530
Subject: [PATCH 16/37] Docker image and containers 10-May-22

---
 docker.txt | 115 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 docker.txt

diff --git a/docker.txt b/docker.txt
new file mode 100644
index 0000000..fd456a8
--- /dev/null
+++ b/docker.txt
@@ -0,0 +1,115 @@
+Docker 
+	Docker is one of the tools that used the idea of the isolated resources to 
+	create a container that allows applications to be packaged with all the 
+	dependencies installed and ran wherever we wanted.
+	
+	Docker can only run on Linux machines this means I cant install Dokcer directly on Windows or any other OS.
+	If I want install Docker on windows then I need to run a Linux VM in windows on top that I need to run Docker.
+
+Virtualization (VM)
+	- VM is way of running virtual OS on top a host OS using a special software called Hyperviser.
+	- VM directly shares the harware of the host OS. 
+
+					VM 					vs 			Containerisation 
+	1. Virtualization at hardware level  		1. Virtualization at OS level 
+	2. Heavyweight - consume more host 			2. Lightweight
+	   resources 	
+	3. VM useses hypervisor 					3. containerisation tool is used 
+	4. limited performace - Boot up time        4. Native performace - usualy boot 
+		is more which is in minutes 			   fast in seconds.
+	5. Cosumes more storage 					5. Shres OS storage means only uses 
+												   required storage.
+	6. Supports all OS 							6. Supports on Linux
+
+host machine 
+	This is the machine in which docker is running 
+	
+Docker image 
+
+	To list images 
+		docker images
+		
+	To download images from docker hub 
+		docker pull <image_name>:<tag>
+
+		note: The default tag will be always latest.
+			  if we wont specify any tag latest will be considered 	
+			  
+	To connect to your docker hub account 
+		docker login 
+
+	To pull a image from your repo 
+		docoker pull <username>/<image_name>:<tag>	
+		
+		ex: docker pull harshajain/my_ubuntu
+		
+	To push a image to your repo 
+
+		1. Create a tag which matches your repo syntax 
+			docker tag <old_name> <new_name>
+			
+			ex: docker tag ubuntu:22.10 harshajain/test:1.0
+		
+		2. Push the image 	
+			docoker push <username>/<image_name>:<tag>	
+		
+			ex: docker push harshajain/test:1.0	
+		
+Docker container 
+	A container is a set of isolated processes and resources. Linux achieves 
+	this by using namespaces, which allows processes to access only resources 
+	in that particular namespace, which allows having a process tree means set 
+	of processes that is completely independent of the rest of the systems processes.
+	
+	Docker definition: A container is a standard unit of software that packages 
+	up code and all its dependencies so the application runs quickly and reliably 
+	from one computing environment to another.
+	
+	To list running containers 
+		docker ps 
+			(or)
+		docker container ls 
+	
+	To list all containers
+		docker ps -a 
+	
+	To list all stopped conatainers
+		docker ps -a --filter status=exited
+		
+	To delete one or more container 	
+		docker rm <conainter_id1> <conainter_id2> .... 
+		
+		To delete a running container 
+			1. Forcefully - docker rm -f <conainter_id>
+			2. Grace fully - docker rm $(docker stop <conainter_id>) 
+											(or)
+							 docker stop <conainter_id> | xargs -I{} docker rm "{}"						
+				
+	To delete all stopped/exited containers 
+		docker rm $(docker ps -aq --filter status=exited)	
+		
+	
+		
+	To check the logs of conatainers 
+		docker logs <container_id>
+
+	To login / get inside a containre 
+		docker attach <container_id>
+			
+	To run a command inside a conatainer 
+		docker exec -it <container_id> <command>
+		
+	To create a container from a docker image 
+		docker run -it -d --name <conainter_name> <image>:<tag> <run_time_command>
+		
+		-it - Interactive Terminal (tty) 
+		-d - deatached mode (when ever we create a container it will auto login to avoid this 
+			we can create a container in detached mode)
+		--name used to provide user defined conatainer name
+		
+		Note: Always use the options before <image>:<tag> <run_time_command>
+		
+		ex: docker run -it -d --name my_jenkins -p 8080:8080 -p 50000:50000 jenkins/jenkins
+		
+Assignment: work with docker commands
+			Try to create a jenkins container (jenkins/jenkins:lts)		
\ No newline at end of file

From 3fa0e476e182d4feab216fcc9ea0b39f24eed5f0 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Tue, 10 May 2022 11:06:43 +0530
Subject: [PATCH 17/37] Docker image and containers 10-May-22

---
 docker.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docker.txt b/docker.txt
index fd456a8..22363a6 100644
--- a/docker.txt
+++ b/docker.txt
@@ -111,5 +111,5 @@ Docker container
 		
 		ex: docker run -it -d --name my_jenkins -p 8080:8080 -p 50000:50000 jenkins/jenkins
 		
-Assignment: work with docker commands
+Assignment: work with docker image and container commands
 			Try to create a jenkins container (jenkins/jenkins:lts)		
\ No newline at end of file

From 32ae2d906b32ea4c0edc5a0cd1ffa9dbf72e7cdf Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Thu, 12 May 2022 10:44:40 +0530
Subject: [PATCH 18/37] Dockerfile 12-May-22

---
 docker.txt | 88 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 81 insertions(+), 7 deletions(-)

diff --git a/docker.txt b/docker.txt
index 22363a6..df3278c 100644
--- a/docker.txt
+++ b/docker.txt
@@ -88,17 +88,18 @@ Docker container
 	To delete all stopped/exited containers 
 		docker rm $(docker ps -aq --filter status=exited)	
 		
-	
+	To run a command inside a conatainer 
+		docker exec -it <container_id> <command>
 		
 	To check the logs of conatainers 
 		docker logs <container_id>
 
 	To login / get inside a containre 
-		docker attach <container_id>
-			
-	To run a command inside a conatainer 
-		docker exec -it <container_id> <command>
-		
+		docker attach <container_ID>  
+				(safe exit <ctrl>+qp)
+					(OR)
+		docker exec -it <container_ID> /bin/bash	
+					
 	To create a container from a docker image 
 		docker run -it -d --name <conainter_name> <image>:<tag> <run_time_command>
 		
@@ -112,4 +113,77 @@ Docker container
 		ex: docker run -it -d --name my_jenkins -p 8080:8080 -p 50000:50000 jenkins/jenkins
 		
 Assignment: work with docker image and container commands
-			Try to create a jenkins container (jenkins/jenkins:lts)		
\ No newline at end of file
+			Try to create a jenkins container (jenkins/jenkins:lts)		
+	
+	docker commit 
+	docker export 
+	docker import 
+	docker save 
+	
+Docker custom image / Dockerfile
+	Dockerfile
+		Dockerfile is used to create custom images by using any stock image or other image as base image.
+		In Dockerfile we can write some set of instructions to update any image.
+	
+		To create image from Dockerfile
+			docker build -t my_ubuntu .
+	
+	FROM ubuntu
+		FROM is the first instruction in the every Dockerfile
+		FROM is used to specify the base image on top which all the other 
+			instruction will run in the same Dockerfile.
+			
+		FROM <image_name>:<tag>
+		
+	RUN 
+		Normal shell command or the commands supported by the base image are executed using this instruction.
+		we can have n number of RUN in a single Dockerfile.
+		
+		Normal command format 
+			RUN <command>
+			
+		exec format 
+			RUN ['<command>','<param1>','<param2>']	
+			RUN ['apt','update']	
+			RUN ['apt','install','-y','git']	
+			RUN ['ls','-lrt']	 
+		
+			
+	ENV 
+		- This instruction is used to set the environment variable inside the container.
+		
+		ENV <variable_name> <value>
+		ENV <variable_name>=<value>
+		
+		multiple 
+		ENV <variable_name>=<value> <variable_name>=<value> <variable_name>=<value> ....
+		
+		To create environment variables at run time 
+			- using -e or --env option at the runtime we can create env variables 
+			- For multiple variables use multiple -e 
+
+		ex:	docker run .... -e <variable_name>=<value> -e <variable_name>=<value> ....	
+		
+		The best way to load multiple env variable is using env file 
+			using --env-file <file_path> at the runtime (with docker run command) we can 
+			load the env file containing n number variables. 
+		
+		
+	COPY and ADD 
+		- Both copy and add instruction is used to copy files and directories from host machine to the image.
+		- The source path to copy files should always be evaluted with reference to Dockerfile.
+		
+		ADD supports extra source formats 
+			- If the source is a compressed file add will automatically 
+			  uncompresses it to the destination.
+			- If the source is a link to a downloadable file it will download 
+			  to the destination.
+			  
+		COPY <source_path_from_build_context> <destination_inside_image>	  
+		ADD <source_path_from_build_context> <destination_inside_image>	  
+		
+	
+	
+		
+	
+				
\ No newline at end of file

From 1e523d55da4cec6cf36cd20ac91e1b6342c2e33d Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Fri, 13 May 2022 10:01:51 +0530
Subject: [PATCH 19/37] Bind Mounts 13-May-22

---
 docker.txt | 45 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/docker.txt b/docker.txt
index df3278c..0213080 100644
--- a/docker.txt
+++ b/docker.txt
@@ -87,6 +87,8 @@ Docker container
 				
 	To delete all stopped/exited containers 
 		docker rm $(docker ps -aq --filter status=exited)	
+					(or)
+		docker container prune
 		
 	To run a command inside a conatainer 
 		docker exec -it <container_id> <command>
@@ -98,8 +100,8 @@ Docker container
 		docker attach <container_ID>  
 				(safe exit <ctrl>+qp)
 					(OR)
-		docker exec -it <container_ID> /bin/bash	
-					
+		docker exec -it <container_ID> /bin/bash		
+	
 	To create a container from a docker image 
 		docker run -it -d --name <conainter_name> <image>:<tag> <run_time_command>
 		
@@ -147,7 +149,6 @@ Docker custom image / Dockerfile
 			RUN ['apt','update']	
 			RUN ['apt','install','-y','git']	
 			RUN ['ls','-lrt']	 
-		
 			
 	ENV 
 		- This instruction is used to set the environment variable inside the container.
@@ -182,7 +183,43 @@ Docker custom image / Dockerfile
 		COPY <source_path_from_build_context> <destination_inside_image>	  
 		ADD <source_path_from_build_context> <destination_inside_image>	  
 		
-	
+		
+	CMD and ENTRYPOINT
+		shell format 
+			CMD "ls -lrt"
+			ENTRYPOINT "ls -lrt"
+			
+		EXEC Format
+			CMD ["ls","-l","-rt"]
+			ENTRYPOINT ["ls","-lrt"]
+			
+		- Both CMD and ENTRYPOINT are used to define the execution command of the container which will be created 
+		  from this image.
+		- If we use multiple CMD or ENTRYPOINT in the same Dockerfile only the latest one will be considered 
+		  and all the other CMD or ENTRYPOINT will be ignored.	
+		- If we use both CMD and ENTRYPOINT in the same Dockerfile, ENTRYPOINT will get the 
+		  higest priority and the command of CMD will become as argumetns to ENTRYPOINT	
+		  
+		 Difference  
+		  -	CMD command can be overridden at the runtime.	
+		  - ENTRYPOINT can't be overridden at the runtime but the runtime command
+		    will become parameters to ENTRYPOINT command.
+		  
+		Note: Q. Can we override ENTRYPOINT 
+				 Yes, after docker 1.6 version docker has given option to over
+					  Entrypoint command at the runtime using --entrypoint 
+					  
+Docker Volumes
+ 	- As the layers inside the image are readonly which means once the image is created 
+	  we cannot change/edit so we cannot put the conatainer data in image.
+	- Container create a top most RW layer and all the runtime data is saved here. 
+	- Container layer is temparary layer, If we loose the container we loose data. so
+	  to retain/persist the container runtime data we need docker volumes.
+
+	Bind Mounts 
+		- we can mount host machine filesystem (files and directories) to the container
+		
+			docker run -v <host_path>:<container_path>
 	
 		
 	

From 561fb3d4dd07d76ae8ef74e04d2a88343dd05ead Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Sat, 14 May 2022 10:19:19 +0530
Subject: [PATCH 20/37] Volumes, namespaces, expose, publish 14-May-22

---
 docker.txt | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

diff --git a/docker.txt b/docker.txt
index 0213080..39e6ae8 100644
--- a/docker.txt
+++ b/docker.txt
@@ -208,7 +208,14 @@ Docker custom image / Dockerfile
 		Note: Q. Can we override ENTRYPOINT 
 				 Yes, after docker 1.6 version docker has given option to over
 					  Entrypoint command at the runtime using --entrypoint 
-					  
+	
+	EXPOSE 
+		EXPOSE <port_number>
+		- Used to expose a port to the docker network 
+		- This is make the  port accessable by all the other containers in the 
+		  same docker network.	
+
+	
 Docker Volumes
  	- As the layers inside the image are readonly which means once the image is created 
 	  we cannot change/edit so we cannot put the conatainer data in image.
@@ -221,6 +228,70 @@ Docker Volumes
 		
 			docker run -v <host_path>:<container_path>
 	
+	Docker Volumes		
+		- These are docker managed filesystem and we use docker commands to manage these
+		  volumes 
+		- Volumes are easier to manage, backup or migrate than bind mounts.
+		- Volumes supports many drivers which means we can maunt many types of filesystem.
+		- Default location of docker volume is /var/lib/docker/volumes  	
+		
+		docker run -v <volume_name>:<container_path>
 		
+		To create volume 
+			docker volume create <volume_name>
+			
+		To list volume 
+			docker volume ls	
+			
+		To Delete volume 
+			docker volume rm <volume_name>
+			
+Namespaces and cgroups
+	- Docker uses linux namespaces to provide isolated workspace for processes called
+	  conatainer
+	- when a container is created, docker creates a set of namespaces for it and provides 
+	  a layer of isolation for container.
+	- Each container run in a different namespace 
 	
+
+	namespace (To list - lsns)
+		cgroups 
+			- Linux OS uses cgroups to manage the availale hardware resoruces such as 
+			  cpu, RAM, Disk, I/O.
+			- we can control tje access and also we can apply the limitations 
+
+			To list - lscgroup	
+		pid - namespace for managing processes (process isolation)
+		user - namespace for non-root user on linux.
+		uts - namespace for unix timesharing system which isolates kernel and version identifiers,
+			  time bonding of process.
+		ipc - (interprocess communication) namespace for managing the process communication.	  
+		mnt - namespace for managing filesystem mounts.
+		net - namespace for managing network interfaces.
+		
+Docker networking 
+	Publish 
+		PUBLISH = Expose + outside world port mapping 
+			
+	- publics will bind the container port to the host port which we can access from 
+	  outside world using <host_ip>:<port_mapped>
+	
+	- To publish a port 
+		docker run -p <host_port>:<container_port> .....
+		
+	-P publish_all
+		It binds all the exposed ports of the container to host machine port
+		
+	To map direct IP address to the host 
+		port to port 
+			ip:<host_port>:<container_port>
+			ip::<container_port>
+			
+	Range of ports 
+		many to one 
+			-p 8080-8090:8080
+		many to many 
+			-p 8080-8085:8086-8091
+			 - The total number of host ports in range should be same as the 
+			   total number of container ports range.
 				
\ No newline at end of file

From cefbaad8509a1095ef12c5e4331d7110679019ae Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Sun, 15 May 2022 10:13:35 +0530
Subject: [PATCH 21/37] Docker networks, multistage, lifecycle, Architecture
 15-May-22

---
 docker.txt | 148 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 144 insertions(+), 4 deletions(-)

diff --git a/docker.txt b/docker.txt
index 39e6ae8..68a096f 100644
--- a/docker.txt
+++ b/docker.txt
@@ -168,7 +168,14 @@ Docker custom image / Dockerfile
 		The best way to load multiple env variable is using env file 
 			using --env-file <file_path> at the runtime (with docker run command) we can 
 			load the env file containing n number variables. 
-		
+	
+	ARG
+		Using ARG we can pass parameters to Dockerfile as user inputs 
+			
+		ARG <var_name>=<default_value>
+
+		To pass the value at build time 
+			docker build --build-arg <var_name>=<value> ....	
 		
 	COPY and ADD 
 		- Both copy and add instruction is used to copy files and directories from host machine to the image.
@@ -215,7 +222,12 @@ Docker custom image / Dockerfile
 		- This is make the  port accessable by all the other containers in the 
 		  same docker network.	
 
-	
+	WORKDIR
+		This is used to set the working directory for all the instructions that follows it
+		such as RUN, CMD, ENTRYPOINT, COPY, ADD
+		
+		WORKDIR <path>
+		
 Docker Volumes
  	- As the layers inside the image are readonly which means once the image is created 
 	  we cannot change/edit so we cannot put the conatainer data in image.
@@ -253,7 +265,6 @@ Namespaces and cgroups
 	  a layer of isolation for container.
 	- Each container run in a different namespace 
 	
-
 	namespace (To list - lsns)
 		cgroups 
 			- Linux OS uses cgroups to manage the availale hardware resoruces such as 
@@ -294,4 +305,133 @@ Docker networking
 			-p 8080-8085:8086-8091
 			 - The total number of host ports in range should be same as the 
 			   total number of container ports range.
-				
\ No newline at end of file
+				
+Docker network types 
+	1. Bridge 
+		- This is a private internal network created by docker on the host machine 
+		  by name docker0	
+		- This is the default network type for all the container which are created 
+          without any network configurations.
+		- By default all the containers in the same bridge can communicate with 
+		  eachother without any extra configuration.	
+		- We cannot use container name for communication only IP address is allowed in 
+		  default bridge.
+
+		Custom bridge 
+			To create bridge network 
+				docker network create --driver bridge my_bride 
+			
+			- In custom bridge containers can communicate with eachother with container 
+			  name and also with IP address.
+			
+	2. Host 		  
+		- This driver removes the network isolation between docker and the host.
+		- The containers are directly connected to host machine network without  
+		  extra layer of any docker network.
+		- Shares the same TCP.IP stack and same namespace of host machine.  
+		- All the network interfaces which are there in host machine are 
+		  accessable by this container.
+
+	3. None 
+		- Containers are not attached to any network by docker.
+		- All the required network configurations need to be done 
+		  manually.
+		- The host or any other containers won't be able to communicate 
+		  with this container untill a custom network is configured.
+		  
+ocker Architecture 
+	Docker Daemon 
+		- A background process that manages docker images, containers, network and volumes.
+		- This Daemon constantly listens for docker API request and processes them.
+	
+	Docker REST API 
+		- API which is used by applictions to interact with the docker daemon. 
+		
+	Docker CLI 
+		- It is a command line interface for interacting with docker daemon through
+		  REST api.
+	
+	Docker Objects 
+
+Benifits of Docker 
+	Flexible: 
+		Complex applictions cab be divided and containerised in small compenets called 
+		microservice. 
+	
+	Lightweight: 
+		Containers share the machine’s OS system kernel and therefore do not require 
+		an OS per application, driving higher server efficiencies and reducing server and licensing costs
+
+	portable: 
+		we can build images anywhere and then deploy to cloud, run anywhere.	
+
+States of conatiner / Lifecycle of container 
+	1. Created - if container is newly created and container is not yet started.
+	2. Running - A currently running container. It means there is no problem 
+				 with container to run the process.
+	3. Exited - A container ran and completed ot executiom with failure.
+	4. paused - A container whose process have been paused. (we can unpause the container)
+	5. Dead - if docker daemon tried and failed to stop a container (host ram full)
+	6. Restarting - container will be in the phase of retarting the main process.
+
+Multistage build 
+	How to optimize docker build process ?
+	How to reduce the size of the docker image or cotainer ? 
+
+	After docker 1.6 version docker released this option.
+	1. There are 2 problems with the normal build process 
+			1. Size: challenge is to keep the image and its containers size as minimal as possible.
+			2. larger the surface area more the application is vurnalable to attacks. 
+	
+		- Multistage build allows us to define multiple FROM in same Dockerfile.
+		- Dependency between multile FROM is maintained by naming FROM using 
+		  AS keyword and we can refer this name in another FROM.
+
+				FROM <base_image> AS <STAGE_NAME>
+				
+		- Only the final FROM image is created leaving back all the other FROM.
+		- Copy only the required files from the named FROM stage like below.
+				FROM final_build
+				COPY --from <STAGE_NAME> <src_named_stage> <dest>
+	
+	2. Always try to use the slim / alpine / stretch version of base image instead 
+	   od using the fully loaded base image.
+	   
+	exapmle: https://github.com/jaintpharsha/docker_multi_build.git		  
+	
+docker-compose 
+	Installation 
+		1. sudo curl -L "https://github.com/docker/compose/releases/download/1.29.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
+		2. sudo chmod +x /usr/local/bin/docker-compose
+		3. sudo ln -s /usr/local/bin/docker-compose /usr/bin/docker-compose
+		
+	- docker-compose is a tool for defining and running multile container docker application with 
+	  a single command.
+	- We use YAML file to do docker related configurations then with a single command 
+	  we can execute this YAML file to create docker objects defined in this file.	
+	  
+	docker-compose.yml 
+		version: "3.8"
+		services:
+			jenkins:
+				image: jenkins/jenkins:lts
+				container_name: dc-jenkins
+				ports:
+					- "8080:8080"
+					- "5000:5000"
+				networks:
+					- my_brid
+			alpine:
+				build: .
+				container_name: dc-ubuntu
+				volumes:
+					- my_vol:/home
+				networks:
+					- my_brid
+		networks:
+			my_brid:
+				driver: bridge
+
+		volumes:
+			my_vol: {} 
+	
\ No newline at end of file

From 8aba4d5a1b0c30ba17a76b6ce33502856bdb4077 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Tue, 17 May 2022 10:55:30 +0530
Subject: [PATCH 22/37] k8s setup 17-May-22

---
 kubernetes.txt | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 kubernetes.txt

diff --git a/kubernetes.txt b/kubernetes.txt
new file mode 100644
index 0000000..55d3e38
--- /dev/null
+++ b/kubernetes.txt
@@ -0,0 +1,67 @@
+Kubernetes Installation 
+	Minimum requirement for K8S master node is (2-core CPU and 2GB Ram)
+	
+	1. sudo apt update 
+	2. sudo apt-get install -y apt-transport-https
+	3. sudo su -
+	4. curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add
+	5. echo 'deb http://apt.kubernetes.io/ kubernetes-xenial main' > /etc/apt/sources.list.d/kubernetes.list
+	
+	6. exit from sudo 
+	7. sudo apt update 
+	8. sudo apt install -y docker.io
+	
+	9. sudo systemctl start docker 
+	10. sudo systemctl enable docker.service 
+	
+	11. sudo apt-get install -y kubelet kubeadm kubectl kubernetes-cni
+	
+	Take ami from the above ec2 instances to create worker nodes 
+	
+	12. Login back to master node,  make sure below steps are executed before running kubeadm init 
+		1. sudo su - 
+		2. docker cgroup driver configuration need to be updated 
+			1. add the below content to the file /etc/docker/daemon.json
+				{
+				  "exec-opts": ["native.cgroupdriver=systemd"]
+				}
+			2. systemctl daemon-reload
+			   systemctl restart docker 
+			   systemctl restart kubectl	
+			
+	13. kubeadm init 
+			if this command executes successfully then we get kubeadm join command with token
+			save this command in seperate file for worker nodes to add to this master.
+
+	14. k8s configurations for kubectl command 
+		1. exit from root 
+		2. copy the default k8s conf file to home 
+			a. mkdir -p $HOME/.kube
+			b. sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
+			c. sudo chown $(id -u):$(id -g) $HOME/.kube/config
+			
+	15. Now Install k8s CNI driver
+			1. sudo sysctl net.bridge.bridge-nf-call-iptables=1
+			2. kubectl apply -f "https://cloud.weave.works/k8s/v1.13/net.yaml"
+			
+			
+	16. Login to worker nodes 
+		a. sudo su -
+		
+		b. update docker cgroup driver configuration need to be updated 
+			1. add the below content to the file /etc/docker/daemon.json
+				{
+				  "exec-opts": ["native.cgroupdriver=systemd"]
+				}
+			2. systemctl daemon-reload 
+			   systemctl restart docker 
+			   systemctl restart kubectl 	
+	
+	17. For now open all ports in master 	
+	
+	18. run the kubeadm join <TOKEN> command which we get from kubeadm inint from master 
+		
+	19. In master node check for the worker nodes.
+			kubectl get nodes 
+			
+			
\ No newline at end of file

From 94268582f6c04e923db86a4d535d3184c309d166 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Thu, 19 May 2022 10:10:02 +0530
Subject: [PATCH 23/37] kubernetes Architecture 19-May-22

---
 kubernetes.txt | 65 +++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 62 insertions(+), 3 deletions(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index 55d3e38..e51d92e 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -43,8 +43,7 @@ Kubernetes Installation
 	15. Now Install k8s CNI driver
 			1. sudo sysctl net.bridge.bridge-nf-call-iptables=1
 			2. kubectl apply -f "https://cloud.weave.works/k8s/v1.13/net.yaml"
-			
-			
+						
 	16. Login to worker nodes 
 		a. sudo su -
 		
@@ -64,4 +63,64 @@ Kubernetes Installation
 	19. In master node check for the worker nodes.
 			kubectl get nodes 
 			
-			
\ No newline at end of file
+kubernetes Architecture 	
+	The architecture of k8s differs from master and worker node 
+
+	Master node components 
+		1. Api Server / kube-api-server
+			- It is the main managemnet point of the cluster and also called 
+			  as brain of the cluster.
+			- All the components are directly connected to API serve, they 
+			  communicate through API server only and no other component will 
+			  communicate directly with eachother.
+			- This is the only component which connects and got access to etcd.
+			- All the cluster requests are authenticated and authorized by API server.
+			- API server has a watch machanism for watching the changes in cluster.
+			
+		2. etcd 
+			- ectd is a distributed , consistent key value store used for 
+			  storing the complete cluster information/data.
+			- ectd contains data such as configuration managemnet of cluster,
+              distributed work and basically complete cluster information.			
+			
+		3. scheduler / kube-scheduler
+			- The scheduler always watches for a new pod request and 
+			  decides which worker node this pod should be created.
+			- Based on the worker node load, affinity and anti-affiny, taint configuration 
+			  pod will be scheduled to a particualr node.
+			  
+		Controller manager /control manager / kube-controller 
+			- It is a daemon that always runs and embeds core control loops known as controllers. 
+			- K8s has some inbuild controllers such as Deployment, DaemonSet, ReplicaSet, Replication controller,
+			  node controller, jobs, cronjob, endpoint controller, namespace controller etc.	
+			
+		Cloud controller manager 
+		
+		
+		
+	Worker node components 
+		kubelet 
+			- It is an agent that runs on each and every worker node and it alsways watches the API 
+			  server for pod related changes running in its worker node.
+			- kubelet always make sure that the assigend pods to its worker node is running.
+			- kubelet is the one which communicates with containarisation tool (docker daemon)
+              through docker API (CRI). 	
+			- work of kubelet is to create and run the pods. Always reports the status of the worker node 
+			  and each pod to API server. (uses a tool call cAdvisor)
+			- Kubelet is the one which runs probes.	
+		
+		kube service proxy 
+			(in k8s service means networking)
+			- Service proxy runs on each and every worker node and is responsble for watching API 
+			  server for any changes in service configuration (any network related configuration).	
+			- Based on the configuration service proxy manages the entire network of worker node.
+
+		Container runtime interface (CRI)
+			- This component initialy identifies the container technology and connects it to kubelet.
+			
+			
+		pod
+			- pods are the smallest deployable object in kuberntes.
+			- pod should contain atleast one container and can have n number of containers.
+			- If pod contains more than one container all the container share the same memory assigned to that pod.
+					
\ No newline at end of file

From 5df397214c725d6d63c5c2b05eab18543593bdef Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Fri, 20 May 2022 09:28:10 +0530
Subject: [PATCH 24/37] YAML syntax 20-May-22

---
 kubernetes.txt | 64 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 63 insertions(+), 1 deletion(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index e51d92e..2060a9b 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -123,4 +123,66 @@ kubernetes Architecture
 			- pods are the smallest deployable object in kuberntes.
 			- pod should contain atleast one container and can have n number of containers.
 			- If pod contains more than one container all the container share the same memory assigned to that pod.
-					
\ No newline at end of file
+
+YAML file 
+	- filetype .yaml or .yml 
+	- YAML file contains key - value pairs where key are fixed and defined by the 
+	  kubernetes and value is user defined configuration.
+	- Values supoorts multiple datatypes - string, Integer, Boolean, Array, List.	
+	
+	example: List representation  
+	
+			1) name: Harsha
+			   hobbies: ["Driving","coding"]
+					
+						(or)
+				
+			   name: Harsha
+			   hobbies: 
+				   - Driving
+				   - coding
+
+example pod 	
+	
+	apiVersion: v1
+		- This is the version of api used to create a k8s object.
+		- The fields are casesensitive and YAML use camelcase.
+		- The type of api are alpha, beta and stable.
+		
+	kind: Pod
+		- here we specify which object we need to create. 
+		- Always object name first letter is capital.
+		
+	metadata:
+	    - This field is used to provide information on the object 
+		  which we are creating.
+		- Information such as name, labels and annotaions. 	
+	
+	spec:
+		- This is used to do the actual configuration of the 
+		  object.
+		  
+apiVersion: v1
+kind: Pod 
+metadata: 
+    name: my-first-pod	
+spec: 
+    containers:
+       - name: my-nginx 
+         image: nginx:latest
+		 ports: 
+		    - containerPort: 80
+	
+TO create / apply a configuration 
+	kubectl apply -f <file>.yml	
+	
+To list objects 
+	kubectl get <obeject_type>
+		ex: List pods - kubectl get pods 
+		    List deployment - kubectl get deployments
+			
+To delete objects 
+	kubectl delete <object_type>
+
+
+Assignment: What happens if we create a pod with kubectl ?		  
\ No newline at end of file

From a1fe3fa1682aed9d134f1cccb7a6912e704c26b2 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Sun, 22 May 2022 10:34:39 +0530
Subject: [PATCH 25/37] selectors labesl annotations deployment daemonset
 22-May-22

---
 kubernetes.txt | 124 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 123 insertions(+), 1 deletion(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index 2060a9b..5b121fd 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -185,4 +185,126 @@ To delete objects
 	kubectl delete <object_type>
 
 
-Assignment: What happens if we create a pod with kubectl ?		  
\ No newline at end of file
+Assignment: What happens if we create a pod with kubectl ?		  
+
+K8S Labels and selectors 
+	- K8S labels is a metadata key value which can be applied to any object in k8s.
+	- Labels are used to identify by using selectors.
+	- Multiple objects can have same label, multiple labels to same object and Label lenght should be less that 63 characters.
+	
+	TO list all labels of a object 
+		kubectl get <obeject_type> <obejct_name> --show-labels 
+	
+	
+	Selectors 
+		- Selectors are used to filter and identifly the labeled k8s object.
+		
+		Equality-Based 
+			- It will use only one label in comparision and it will look for objects with exact same 
+			  string in label.
+			- we can use 3 types of operators equal ( = or == ) and not-qual ( != )	
+		
+			example: 
+				selectors: 
+					matchLabels: 
+						app=nginx 
+						   (or)
+						app: nginx   
+		
+		set-based 
+			- This type of selector allows us to filter objects based on multiple set of values to a label key.
+			- 3 types of operators we can use in, notin and exists.
+
+				example: 
+					selectors: 
+						matchLabels: 
+							app in (nginx, my-nginx)
+							app exits (nginx, my-nginx)
+							app notin (nginx, my-nginx)
+Annotations 
+	- These are used for record purpose only and to provide some user information to objects.
+	- These are non-identifying metadata so we cannot use selectors on annotations.
+
+	example: personal_info, phone_number, imageregistry, author	
+	
+Assignment: Difference b/w set-based and equality-based selector.
+			Difference b/w labels and annotations.
+
+ReplicaSet vs Replication Controller
+	- Both ensures that a specified number of pod replicas are alyways running at a given point of time.
+	- Replication controller is a very old way of replicating the pos and now it is replaced by ReplicaSet
+      
+	- The only differenece b/w them is their selector types.
+		Replication Controller supports only equality-based selector. 
+		ReplicaSet supports both equality-based and set-based selectors.
+
+Deployment controller / Deployment / k8s deployment 
+	- Deployment is used to create replicas of pod and it makes sure at a given point of time 
+	  the number of replicas of pod is alway running. 
+	- Deployment internally uses ReplicaSet to replicate the pods.
+	- If we update the configuration in deployment it will automatically updates it to all the pods.
+	- Rollout and Rollback of pod update is possible.
+	- we can pause a deployment whenerver we need.
+	- Deployment has got its own internal autoscaller which is of type horizontal scaller. 
+		To apply calling 
+			kubectl autoscale deployment.v1.apps/<deployment_name> --min=5 --max=20 --cpu-percent=50	
+	- scaleup and scaledown is possible by increasing and decreasing the replica count at any given 
+	  point of time.
+		kubectl scale deployment.v1.apps/<deployment_name> --replicas=10	
+	
+	- deployment is a cluster level object.
+	
+		deployment = pod + ReplicaSet + autoscaling + RollingUpdates 
+	
+	Deployment spec file.
+		
+		apiVersion: apps/v1
+		kind: Deployment
+		metadata:
+		  name: nginx-deployment-new
+		  labels:
+			app: my-deployment-nginx
+		spec:
+		  replicas: 5
+		  selector:
+			matchLabels:
+			  app=nginx
+		  template:
+			metadata:
+			  labels:
+				app: nginx
+			spec:
+			  containers:
+			  - name: nginx
+				image: nginx:1.14.2
+				ports:
+				- containerPort: 80
+	
+Assignment: demo on selectors types 
+	
+DaemonSet
+	- DaemonSet ensures that a copy of pod is always running on all the worker nodes in the cluster.
+	-If a new node is added or if deleted DaemonSet will automatically adds/deletes the pod.
+
+	usage: 
+		- we use DaemonSet to deploy monitoring agents in every worker node.
+		- Log collection daemons: to grab the logs from worker and all the pods running in it.
+		
+apiVersion: apps/v1
+kind: DaemonSet
+metadata:
+  name: nginx-daemonset
+spec:
+  selector:
+	matchLabels:
+	  app: daemonset-nginx
+  template:
+	metadata:
+	  labels:
+		app: daemonset-nginx
+	spec:
+	  containers:
+	  - name: nginx
+		image: nginx:1.14.2
+		ports:
+		 - containerPort: 80
\ No newline at end of file

From 1da038b72ec1dda85e19917fdc2a0f9975ddd270 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Tue, 24 May 2022 10:31:09 +0530
Subject: [PATCH 26/37] stateful/stateless StatefulSet monolothic/microservices
 service-NP,CI 24-May-22

---
 kubernetes.txt | 94 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 93 insertions(+), 1 deletion(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index 5b121fd..034894b 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -307,4 +307,96 @@ spec:
 	  - name: nginx
 		image: nginx:1.14.2
 		ports:
-		 - containerPort: 80
\ No newline at end of file
+		 - containerPort: 80
+		 
+Statefull Applications 
+	- User session data is saved at the server side.
+	- if server goes down, it is difficult to transfer the session data to other server. 
+	- This type of application will not work, if we want to implement autoscalling.
+	
+Stateless Applications
+	- user sessiondata is never saved at the server side.
+	- using a common authentication gateway / client token method to validate the users 
+	  once for multiple microservices.	
+		
+https://medium.com/tech-tajawal/microservice-authentication-and-authorization-solutions-e0e5e74b248a		
+
+Monolothic and Microservice architecture 
+
+	Monolothic architecture
+		- A monolothic application has a single code base with multiple moduels in it.
+		- It is a single build for entire application.
+		- To make minor changes to application, we need to re-build and re-deploy the 
+		  complete application.
+		- scalling is very challenging.
+			
+	Microservice architecture 
+		- A microservice application is composed of small (micro) services. 
+		- Each service will have a different code base.
+		- Application are divided into as small as possible sub applications called services
+		  which are independent to each other which are called loosly coupled.	
+		- Each service can be managed seperately and it is deployable seperately.
+		- Services need not to share same technology stack or frameworks.		 
+
+StatefulSet 
+	- StatefulSet = Deployment + sticky identity for each and every pod replica.
+	- Unlike a deployment a StatefulSet maintains a sticky identity for each of the pod.
+		
+Node controller 
+	- Looks for node statuses and reponds to API server only when a node is down.
+
+Endpoint Controller
+	- Populates the information of endpoints of all the objects.	
+		
+Service (svc)
+	- Service is an REST api objects with set of policies for defining the 
+	  access to set of pods.
+	- Services are the default load balancer in k8s.
+	- services are always created and works at cluster level.
+	- services are the networking configurations which we do in k8s.
+	- k8s prefers to use 30000 - 50000 range of ports to define services.
+
+1. ClusterIP
+	- This is the default type of service which exposes the IPs of pod to the other pods 
+	  with in the same cluster.
+	- ClusterIP cannot be accessed outside cluster.
+	- services are the default loadbalancers of k8s.
+	
+	apiVersion: v1 
+	kind: Service 
+	metadata:
+	     name: my-svc 
+	spec: 
+		type: ClusterIP
+		selector: 
+			app: my-nginx 
+		ports: 
+			- name: http
+			  port: 30080
+			  targetPort: 8080	
+
+2. nodePort 
+	- A nodeport service is the most primitive way to get the external traffic directed to our services / applications 
+	  running inside a pod within the cluster.
+	- By default NodePort acts as a load balancer. 
+	- Automatically a ClusterIP will be created internally. 
+	
+		NodePort = ClusterIP + a port mapping to the all the nodes of cluster.
+		
+	- If we wont specify any port while creating nodeport, k8s will automatically asign a port between the range 30000 - 32767
+	- By default nodeport will open the port in all the node in cluster including master node.	
+	
+	apiVersion: v1 
+	kind: Service 
+	metadata:
+	     name: my-svc 
+	spec: 
+		type: NodePort
+		selector: 
+			app: my-nginx 
+		ports: 
+			- name: http
+			  nodePort:30082	
+			  port: 8080
+			  targetPort: 80
+					 
\ No newline at end of file

From 95e96544860f72a628f7cad923961abb7f9cab12 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Wed, 25 May 2022 10:25:38 +0530
Subject: [PATCH 27/37] namespaces 25-May-22

---
 app/Dockerfile       |  6 ++++
 app/main.py          | 18 ++++++++++
 app/requirements.txt |  1 +
 kubernetes.txt       | 85 +++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 109 insertions(+), 1 deletion(-)
 create mode 100644 app/Dockerfile
 create mode 100644 app/main.py
 create mode 100644 app/requirements.txt

diff --git a/app/Dockerfile b/app/Dockerfile
new file mode 100644
index 0000000..6c71c97
--- /dev/null
+++ b/app/Dockerfile
@@ -0,0 +1,6 @@
+FROM python
+WORKDIR /app
+COPY main.py /app
+COPY requirements.txt /app
+RUN pip install -r requirements.txt 
+ENTRYPOINT python main.py
diff --git a/app/main.py b/app/main.py
new file mode 100644
index 0000000..26dbe5f
--- /dev/null
+++ b/app/main.py
@@ -0,0 +1,18 @@
+from flask import Flask 
+import socket, os
+
+app = Flask(__name__) 
+
+@app.route('/')
+def print_ip(): 
+    hostname = socket.gethostname()
+    local_ip = socket.gethostbyname(hostname)
+    return local_ip
+    # return "This is homepage or root /"
+
+@app.route('/login')
+def print_login(): 
+    return "This is login page or path /login"
+
+if __name__ == "__main__":
+    app.run(host="0.0.0.0", port=80)    
diff --git a/app/requirements.txt b/app/requirements.txt
new file mode 100644
index 0000000..8ab6294
--- /dev/null
+++ b/app/requirements.txt
@@ -0,0 +1 @@
+flask
\ No newline at end of file
diff --git a/kubernetes.txt b/kubernetes.txt
index 034894b..5949ac0 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -399,4 +399,87 @@ Service (svc)
 			  nodePort:30082	
 			  port: 8080
 			  targetPort: 80
-					 
\ No newline at end of file
+			  
+3. Load Balancer
+	- It is a tyoe of service which is used to link exernatl load balancer to the cluster.
+	- This type of serviec is used by cloud providers and this service is completely depends on cloud providers. 
+	- K8s now proides a better alternative for this service type which is called Ingress.
+
+Assignment: 
+	
+How to use custom images / connect to a registry through k8s 
+	1. Login to the docker hub account 
+		  docker login 
+	2. Create a app to print ip 
+			using flask 
+	3. 	push the image to your registry 
+	4 use the above custom image in k8s spec file.
+	
+		image: <username>/<regirty_name>:<tag>
+		imagePullPolicy: IfNotPresent
+		
+	5. Create a service of type NodePort attaching the above pods 
+		
+namespaces 
+	- k8s namespaces is a way of applying abstraction / isolation to support multiple 
+	  virtual clusters of k8s objects with in the same physical cluster.
+	- Each and every object in k8s must be in a namespac.
+	- If we wont specify namespace, objects will be created in default namespace of k8s.
+    - namespaces are cluster level.
+	- by default pods in same namespace can communicate with eachother.
+	- Namespace are only hidden from eachother but not fully isolated because one 
+	  service in a namespace can talk to another service in another namespace using 
+	  fullname (service/<service_name>) followed by namespace name
+	
+	usage: we can apply environment based logical separation on cluster. 
+		
+	Type of deafault NS
+	1. default
+	   - This NS is used for all the objects which are not belongs to any other namespace.
+	   - If we wont specify any namespace while creating an object in k8s then 
+         that object will be created in deafult namespace.
+			
+	2. kube-system 
+	   - This namespace is always used for objects created by the k8s system.
+	   
+	3. kube-public 
+	   - The objects in this namespace are available or accessable to all.
+       - All the objects in this namespace are made public.
+
+	4. kube-node-lease 
+	   - This namespace holds lease objects assosiated with each node.
+	   - Node lease allows the kubelet to send heartbeats so that the control palne can 
+		 detect node failure.
+	
+	To list namespace
+		kubectl get namespaces 
+	
+	To list objects in a namespace 
+		kubectl get pods --namepsace <NS_name> 
+					(OR)
+		kubectl get pods -n <NS_name> 
+	
+	To list obects from all namespaces
+		kubectl get pods --all-namespaces
+		
+	To create a namespace 
+		kubectl create namespace <ns_name>
+		
+	To create k8s object in a namespace 
+		1. in the spec file 
+			metadata: 
+				namespace: <ns_name>
+				
+		2. Using the apply command 
+			kubectl apply -n <ns_name> -f <spec>.yml
+		
+		Note: what if we use both inside specfile and also in apply command 
+				- apply command check and compares the namespace and wont allow to create the obejct if the namespace is different.
+
+Assignment: try exec to a pod 				
+	
+	- pod to pod communication is open if the 2 pods are in the same namespace.	
+	- If the pods are in different namespace by default they can't communicate we need a service object for this.
+	
+	How a microservice will communicate with other microservice
+	What is service discovery in k8s 
\ No newline at end of file

From 982a23760137812e436c37201266bfa94e83aa12 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Thu, 26 May 2022 12:59:43 +0530
Subject: [PATCH 28/37] headless service 26-May-22

---
 kubernetes.txt | 73 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 71 insertions(+), 2 deletions(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index 5949ac0..75dd4c5 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -481,5 +481,74 @@ Assignment: try exec to a pod
 	- pod to pod communication is open if the 2 pods are in the same namespace.	
 	- If the pods are in different namespace by default they can't communicate we need a service object for this.
 	
-	How a microservice will communicate with other microservice
-	What is service discovery in k8s 
\ No newline at end of file
+
+How a microservice will communicate with other microservice
+What is service discovery in k8s 
+	
+Service discovery 
+	There are 2 ways of dicovering a service in k8s 
+	
+		1. Services 
+			 we can use the full name of service to discovery a microservice (pod).
+			 	service/<service_name>
+				
+		2. DNS 
+			- DNS server is added to the cluster in order to watch the k8s service request.
+			- API server will create DNS records for each new service.
+			- Record A type is used in k8s service discovery and this DNS is created on service
+			  and pod objects.
+			
+			syntax of k8s DNS 
+				<object_name>.<namepsace_name>.<object_type>.<k8s_domian>
+				
+				ex: np-ip-app.default.svc.cluster.local
+		
+		3. ENV variables 
+			- which ever the pod that runs on a node, k8s adds environment variables for 
+			  each of them to identify the service running in it.
+			  
+		https://dev.to/narasimha1997/communication-between-microservices-in-a-kubernetes-cluster-1n41	
+		
+Headless service 
+	headless service 
+		  - When we neither need nor want loadbalancig and a single IP point to a service, we need use headless service.
+		  - Headless service returns all the ips of the pods it is selecting.
+		  - headless serivce is created by specifing none for clusterIP 
+		  - headless service is usually used with statefulsets.
+		  
+	headless with in cluster 
+
+		apiVersion: v1 
+		kind: Service 
+		metadata:
+			 name: my-svc 
+		spec: 
+			clusterIP: None
+			selector: 
+				app: my-nginx 
+			ports: 
+				- name: http
+				  port: 30080
+				  targetPort: 8080
+				  
+	headless with nodeport 			  
+		nodePort = headless + port mapping 
+		
+		apiVersion: v1 
+		kind: Service 
+		metadata:
+			 name: my-svc 
+		spec: 
+			clusterIP: None
+			type: NodePort
+			selector: 
+				app: my-nginx 
+			ports: 
+				- name: http
+				  nodePort:30082	
+				  port: 8080
+				  targetPort: 80
+				  
+	1. Create a headless service with statefulsets
+	2. Login to any one of pod 
+	3. apt install dnsutils and do nslookup <service_name>	
\ No newline at end of file

From 163ab11927c0b280699f97e4bc88b703909f72af Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Fri, 27 May 2022 10:05:36 +0530
Subject: [PATCH 29/37] pv, pvc, pod status and lifecycle 27-May-22

---
 kubernetes.txt | 115 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 114 insertions(+), 1 deletion(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index 75dd4c5..0bcaa12 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -551,4 +551,117 @@ Headless service
 				  
 	1. Create a headless service with statefulsets
 	2. Login to any one of pod 
-	3. apt install dnsutils and do nslookup <service_name>	
\ No newline at end of file
+	3. apt install dnsutils and do nslookup <service_name>	
+	
+pod phases / status / states / life cycle 
+	1. pending 
+		- This is the status of pod when pod will be waiting for k8s cluster to accept it.
+		- pod will be downloading the image from registry.
+		- pod wiil be in pending till the scheduler assigns a node to the pod.
+	
+	2. Running 
+		- The pod has been assigned a node and all the containers inside the pod is running.
+		- Atleast one container is in running state and others in starting or restarting state then pod will show 
+		  running state.
+
+	3. Failed 
+		- All the container in the pod should not be running and any one container being terminated in failure.
+		
+	4. Succeeded 
+		- ALl the containers in pod have been terminated successfully/gracefully.
+		
+	5. Unknown 
+		- For some reason the state of the pod could not be obtaied by API server.
+		- The status may occur when k8s cannot communicate with the kubelet or the worker node.
+	
+	
+terminating 
+	- when pod is being deleted.
+	
+container status 
+	Running 
+		- Means container is running the process inside without any error 
+	Terminated
+		- Process inside the container has completed the execution or may be failed due to some error.
+	waiting 
+		- If a container is not running or neither in terminated state.
+	
+Common errors
+	ImagePullBackOff 
+		- Docker image registry is not accessible.
+		- Image name / tag version specified is incorrent.
+	CrashLoopBackOff
+        - We get this error when probe check has failed.
+		- Docker image may be faulty.
+	RunContainerError 
+		- Configmap / secrets are missing. 
+		- Volumes are not available 
+		
+		
+k8s volumes 
+	persistent volume (pv)
+		- It is a storage space which can be claimend to any pod in the cluster.
+		- These are cluster level object and not bound to namespace.
+		
+		we can control the access to volume in 3 ways:
+			- ReadOnlyMany(ROX) allows being mounted by multiple nodes in read-only mode.
+			- ReadWriteOnce(RWO) allows being mounted by a single node in read-write mode.
+			- ReadWriteMany(RWX) allows multiple nodes to be mounted in read-write mode.
+		
+		Note: If we need write access to volume from multiple pods scheduled in mulitple nodes then use ReadWrtieMany
+		
+	apiVersion: v1
+	kind: PersistentVolume
+	metadata:	
+		name: my-pv
+		labels: 
+			volume: test
+	spec: 
+		storageClassName: local 
+		accessModes: 
+			- ReadWriteOnce
+		capacity: 
+			storage: 2Gi
+		hostPath: 
+		    path: "/home/ubuntu/my-pv-volume" 
+			   
+	Persistent volume claim (pvc)
+		- This is the object used to claim / mount the required amount of storage from persistent volume to any 
+		  pod in the cluster.
+		- After we create the PersistentVolumeClaim, the Kubernetes control plane looks for a PersistentVolume that 
+		  satisfies the claim's requirements. 
+		- If the control plane finds a suitable PersistentVolume with the same StorageClass, it binds the claim to the volume.
+	
+	apiVersion: v1
+	kind: PersistentVolumeClaim
+	metadata:	
+		name: my-pvc
+	spec: 
+		storageClassName: local 
+		accessModes: 
+			- ReadWriteOnce
+		resources: 
+		    requests:
+                storage: 1Gi 
+        	
+	using this in a pod 
+	
+	apiVersion: v1
+	kind: Pod 
+	metadata: 
+		name: my-pvc-pod	
+	spec: 
+        volumes: 
+		    - name: pvc-volume
+			  persistentVolumeClaim: 
+			       claimName: my-pvc # This name should be same the PVC object name
+		containers:
+		   - name: my-nginx 
+			 image: nginx:latest
+			 ports: 
+				- containerPort: 80
+			 volumeMounts: 
+			    - mountPath: "/usr/share/nginx/html"
+				  name: pvc-volume # This name should be same as the above volume name 
+
+			   	
\ No newline at end of file

From ac077f8cb9b48f66489a9f094585061f8d5f4dde Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Sat, 28 May 2022 10:47:58 +0530
Subject: [PATCH 30/37] pod patterns / container types 28-May-22

---
 kubernetes.txt | 102 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 101 insertions(+), 1 deletion(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index 0bcaa12..c7b126c 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -664,4 +664,104 @@ k8s volumes
 			    - mountPath: "/usr/share/nginx/html"
 				  name: pvc-volume # This name should be same as the above volume name 
 
-			   	
\ No newline at end of file
+init container 
+	- init containers are the containers that will run completely before starting 
+		  the main app container.
+	- This provides a lifecycle at the startup and we can define things for 
+      initialization purpose.
+    - kubernetes has stopped support of probes in init containers.
+    - These are pod level objects.
+	- we can use this container to have some deply on the startup of the main container.
+	
+	
+	These are some of the scenarios where you can use this pattern
+		- You can use this pattern where your application or main containers need some
+		  prerequisites such as installing some software, database setup, permissions on the file
+		  system before starting.
+		- You can use this pattern where you want to delay the start of the main containers.
+	
+		apiVersion: v1
+		kind: Pod
+		metadata:
+		  name: init-container
+		  labels:
+			 app: init-app
+		spec:
+		  containers:
+			- name: nginx
+			  image: nginx:1.14.2
+			  ports:
+				- containerPort: 80
+			  volumeMounts:
+				- mountPath: "/usr/share/nginx/html"
+				  name: workdir
+		  initContainers:
+			- name: busybox
+			  image: busybox
+			  command: ["/bin/sh"]
+			  args: ["-c","echo '<html><h1>I am init container new version</h1></html>' >> /work-dir/index.html"]
+			  volumeMounts:
+				- mountPath: "/work-dir"
+				  name: workdir
+		  dnsPolicy: Default
+		  volumes:
+			- name: workdir
+			  emptyDir: {}
+		
+		1. login to pod 
+				kubectl exec -it <pod_name> -- /bin/sh 
+		2. apt update && apt install -y curl 
+		3. curl localhost
+			
+		To check the log of particular container out of multiple in a pod 
+			kubectl logs <pod_name> -c <container_name>
+			
+sidecat container 
+	- These are the containers that will run along with the main app container.
+	- we have a app conaitner which is working fine but we want to extend the 
+	  functionality without changing the existing code in main container for this 
+      purpose we can use sidecar container.
+    - we use this container to feed the log data to monitoring tools.	
+	
+	These are some of the scenarios where you can use this pattern
+		- Whenever you want to extend the functionality of the existing single container pod without
+		  touching the existing one.
+		- Whenever you want to enhance the functionality of the existing single container pod
+		  without touching the existing one.
+		- You can use this pattern to synchronize the main container code with the git server pull.
+		- You can use this pattern for sending log events to the external server.
+		- You can use this pattern for network-related tasks.
+		
+	apiVersion: v1
+	kind: Pod
+	metadata:
+	  name: sidecar-container
+	  labels:
+		 app: adaptor-app
+	spec:
+	  containers:
+		- name: nginx
+		  image: nginx:1.14.2
+		  ports:
+			- containerPort: 80
+		  volumeMounts:
+			- mountPath: "/var/log/nginx"
+			  name: logs-dir
+		- name: side-car
+		  image: busybox
+		  command: ["/bin/sh"]
+		  args: ["-c","while true; do cat /var/log/nginx/access.log /var/log/nginx/error.log; sleep 10; done"]
+		  volumeMounts:
+			- mountPath: "/var/log/nginx"
+			  name: logs-dir
+	  dnsPolicy: Default
+	  volumes:
+		- name: logs-dir
+		  emptyDir: {}
+			  
+	
+	Adaptor container 
+		- In this patter we use a sidecar container to feed the log data to a monotoring 
+		  tool.
+	
+	https://www.magalix.com/blog/kubernetes-patterns-the-ambassador-pattern
\ No newline at end of file

From e1d8aea34ed5805cfe05b8ce181024381ba310ba Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Mon, 30 May 2022 09:59:14 +0530
Subject: [PATCH 31/37] probes 30-May-22

---
 app/main.py    |   6 +++
 kubernetes.txt | 129 ++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 134 insertions(+), 1 deletion(-)

diff --git a/app/main.py b/app/main.py
index 26dbe5f..ec5e281 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1,4 +1,5 @@
 from flask import Flask 
+from flask import jsonify
 import socket, os
 
 app = Flask(__name__) 
@@ -14,5 +15,10 @@ def print_ip():
 def print_login(): 
     return "This is login page or path /login"
 
+@app.route('/any_path')
+def print_login():
+    resp = jsonify(success=True) 
+    return resp
+    
 if __name__ == "__main__":
     app.run(host="0.0.0.0", port=80)    
diff --git a/kubernetes.txt b/kubernetes.txt
index c7b126c..bd0c228 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -764,4 +764,131 @@ sidecat container
 		- In this patter we use a sidecar container to feed the log data to a monotoring 
 		  tool.
 	
-	https://www.magalix.com/blog/kubernetes-patterns-the-ambassador-pattern
\ No newline at end of file
+	https://www.magalix.com/blog/kubernetes-patterns-the-ambassador-pattern
+	
+Probes
+- probe is a periodic call to some applciation endpoints within a container.
+	- probes can track success or failure of the other applications.
+	- When there is a subsequent failure occures we can defie probe to get triggered.
+	- when subsequent success after a failure we can define probe to get triggered.
+	- probes works at container level.
+	
+	Common fields in probes 
+		initialDelaySeconds
+			- After the container has started the number of seconds to wait before the probe os triggered.
+		periodSeconds 
+			- The number of seconds interval the probe should be executed. (Default 10 seconds and minimum 1 second)
+		timeoutSeconds 
+			- Number of seconds after which probe timeouts. (default 1)
+			
+		failureThreshold
+			- When a probe fails this is the number of subsequent fail times the probe checks the status of application.
+			- After the number of subsequent failure then probe fails.
+			- Default value 3 with minimum value 1
+		
+		successThreshold 
+			- minimum number of subsequent success for a probe. 
+			- Default value is 1
+			
+		Endpoints 
+			http probes (httpGet)
+				host - hostname to conenct and probe will check the status of this hostname 
+				     - Default is the IP of current pod 
+					 ex: www.google.com
+				path - exact path to access the application on the http server 
+					 ex: /gmail
+				httpHeaders
+					- can send custom header messages with the request.
+				port 
+					- Name or number of the port to access the application 
+					
+			TCP probes 
+				port 
+					- Name or number of the port to access the application
+			
+			exec 
+				commad 
+				  - we execute a command and check its status.
+		
+Liveness probe 
+		- The livenessprobe is used to determine if the applciation inside the container 
+		  is healthy or needs to be restarted.	
+		- If livenessprobe fails it will mark the container to be retarted by kubelet.
+		
+	1. LivenessPRobe with http 
+		
+		apiVersion: v1
+		kind: Pod 
+		metadata: 
+			name: liveness-http	
+		spec: 
+			containers:
+			   - name: liveness 
+				 image: k8s.gcr.io/liveness
+				 args:
+					- /server
+				 livenessProbe:
+				    httpGet:
+				  	   path: /healthz
+				  	   port: 8080
+				    initialDelaySeconds: 3
+				    periodSeconds: 3	
+		
+	2. TCP 
+		livenessProbe:
+			tcpSocket:
+			   port: 8080
+			initialDelaySeconds: 3
+			periodSeconds: 3
+	3. exec 
+		livenessProbe:
+			exec:
+			   command: ["",""]
+			initialDelaySeconds: 3
+			periodSeconds: 3
+	
+	4. named port 
+		ports: 
+			- name: liveness-port 
+			  containerPort: 8080
+              hostPort: 8080
+		livenessProbe:
+			httpGet:
+			   path: /healthz
+			   port: liveness-port
+			initialDelaySeconds: 3
+			periodSeconds: 3			
+	
+Readiness Probe 
+	- ReadinessProbe is used to determine that a application running inside a 
+	  container is in a state to accept the traffic.
+    - When this probe is successful, the traffic from the loadbalancer is allowed 
+	  to the application inside the conatiner.
+	- When this probe is fails, the traffic from the loadbalancer is halted
+	  to the application inside the conatiner.
+	readinessProbe: 
+		tcpSocket: 
+			port: 8080
+		initialDelaySeconds: 15
+		periodSeconds: 10
+		
+Startup Probe 
+	- This probe will run at the initial start of the container.
+	- This probe allows us to give maximum startup time for application before 
+	  running livenessProbe or readinessprobe.
+	  
+	startupProbe: 
+	    httpGet: 
+		   path: /healtz
+		   port: 8080
+		initialDelaySeconds: 3
+	    periodSeconds: 3   
+
+Assigment: create livenessProbe and readinessprobe with tcp, http, exec 	
+	
+		
+		
+			
+			
+		
+	
\ No newline at end of file

From b0408efbefa172f80075d616a5193290b7446366 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Fri, 3 Jun 2022 10:04:22 +0530
Subject: [PATCH 32/37] configmaps 03-June-22

---
 kubernetes.txt | 134 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 132 insertions(+), 2 deletions(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index bd0c228..e3a4e90 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -499,7 +499,7 @@ Service discovery
 			  and pod objects.
 			
 			syntax of k8s DNS 
-				<object_name>.<namepsace_name>.<object_type>.<k8s_domian>
+				<object_name>.<namepsace_name>.<object_type>.cluster.local
 				
 				ex: np-ip-app.default.svc.cluster.local
 		
@@ -885,10 +885,140 @@ Startup Probe
 	    periodSeconds: 3   
 
 Assigment: create livenessProbe and readinessprobe with tcp, http, exec 	
+
+
+Configmaps and Secrets 
+	- Configmaps are k8s object that allow us to seperate the configuration data from 
+	  the image content of the pod.
+	- using this we can inject the environment variables to the pod containers.
+    - By deafault data is not encrypted in configmaps so it is better to use these for 
+	  non-confidential data.
+
+	Create a configmap
+		1. Create a file by name "app.properties"
+			environment=test
+			database_url="192.168.1.1"
+			database_password="adjhfgjladhgalhg"
+			
+		2. Load the single config file 
+			kubectl create configmap <configmap_name> --from-file configs/app.properties
+
+		   Load the multiple config files 	
+			kubectl create configmap <configmap_name> --from-file configs/
+			
+		   Create configmap spec file 
+				apiVersion: v1
+				kind: ConfigMap
+				metadata:
+				   name: test-configmap
+				data:
+				   environment: test
+				   app: frontend
+			
+		3. To use configmaps to inject env varible in a pod
+			
+				apiVersion: v1
+				kind: Pod
+				metadata:
+				  name: nginx-deployment-new
+				spec:
+				    containers:
+					  - name: nginx
+						image: nginx:1.14.2
+						ports:
+						- containerPort: 80
+						env:
+						  - name: CURRENT_ENV
+						    valueFrom: 
+                                configMapKeyRef: 							
+									name: test-configmap
+									key: environment
+						  - name: DB_URL
+						    valueFrom: 
+                                configMapKeyRef: 							
+									name: test-configmap
+									key: database_url			
+		
+	SECRETS	
 	
+	- using secrets we can inject the environment variables to the pod containers in encrypted.
+    - By deafault secrets data will be in base64 format and we use secrets for confidential data.
 		
+
+	Create a configmap
+		1. Create values in base64 format 
+			echo "<value>" | base64 
+				output: <base64_value>
+			echo "<value1>" | base64 
+				output: <base64_value1>
 		
+		2. Load the single config file 
+			kubectl create secret <configmap_name> --from-file configs/app.properties
+
+		   Load the multiple config files 	
+			kubectl create secret <configmap_name> --from-file configs/
 			
+		   Create configmap spec file 
+				apiVersion: v1
+				kind: Secret
+				metadata:
+				   name: test-secret
+				data:
+				   dburl: <base64_value>
+				   dbpassword: <base64_value1>
 			
+		3. To use secrets to inject env varible in a pod
+				apiVersion: v1
+				kind: Pod
+				metadata:
+				  name: nginx-deployment-new
+				spec:
+				    containers:
+					  - name: nginx
+						image: nginx:1.14.2
+						ports:
+						- containerPort: 80
+						env:
+						  - name: DB_URL
+						    valueFrom: 
+                                secretKeyRef: 							
+									name: test-secret
+									key: dburl
+						  - name: DB_PASSWORD
+						    valueFrom: 
+                                secretKeyRef: 							
+									name: test-secret
+									key: dbpassword		
 		
-	
\ No newline at end of file
+How to create a pod on a particular worker pod 
+	1. Node selector 
+		- Node selector is a way of binding pod to a worker node or nodes based on the 
+		  node labels.
+		- We cannot use any logical expresions type of selection.  
+	
+		create a label to worker node 
+			kubectl label node <node_name> <key>=<value>
+			
+		Use nodeSelector with the same label created to create pods in the same worker node
+			apiVersion: apps/v1
+			kind: Deployment
+			metadata:
+			  name: nginx-deployment
+			spec:
+			  replicas: 6
+			  selector:
+				matchLabels:
+				  app: ipapp
+			  template:
+				metadata:
+				  labels:
+					app: ipapp
+				spec:
+				  nodeSelector:
+					<key>: <value>
+				  containers:
+				  - name: nginx
+					image: nginx:latest
+					ports:
+					- containerPort: 80
+				
\ No newline at end of file

From 336e44cf4826dc9273581c1b7429b3f5474aea7c Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Sat, 4 Jun 2022 10:02:17 +0530
Subject: [PATCH 33/37] RBAC 04-June-22

---
 kubernetes.txt | 127 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 126 insertions(+), 1 deletion(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index e3a4e90..eaeb52e 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -1021,4 +1021,129 @@ How to create a pod on a particular worker pod
 					image: nginx:latest
 					ports:
 					- containerPort: 80
-				
\ No newline at end of file
+
+service-controller
+endpoint-controller
+node-controller
+namespace-controller
+				
+Role-Based access control 
+	- accounts 
+	- Roles 
+	- Binding of roles 
+	
+	Accounts 
+		1. USER ACCOUNT 
+			it is used for human users to control the access to k8s.
+		
+		2. SERVICE ACCOUNT 
+			- It is used by the applications which need the access to the cluster.
+			- Any application running inside or outside the cluster need a service account.
+			
+			- We use a bearer token to authenticate the Service account. Beares token 
+			  is created and attached to SA using secrets.
+		
+		To create a service account 
+			kubectl create sa <account_name>
+			
+			Create a token for sa 
+				apiVersion: v1
+				kind: Secret
+				metadata:
+				  name: test-sa-token
+				  annotations:
+					kubernetes.io/service-account.name: <account_name>
+				type: kubernetes.io/service-account-token
+		
+		use this account in an application 
+			
+			apiVersion: v1
+			kind: Pod
+			metadata:
+			  name: nginx-deployment-new
+			spec:
+				serviceAccountName: test
+			    containers:
+				  - name: nginx
+					image: nginx:1.14.2
+					ports:
+					- containerPort: 80
+			
+Roles 
+	- For a account we can define set of rules to control the access to k8s resource.
+	- Roles are always userdifined which need to be attached to a account.
+	- Roles works for only namepsace. Roles are always defined for a namepsace.
+
+	common fields in roles 
+		apiGroups: List of apis to control the access
+		Subject: User account, serviceaccount or Groups.
+		Resources: K8S objects on which we want to define this roles
+				   ex: pods, deployments etc...
+		Verbs: The operations/actions that can be performed.
+				ex: ["get","list","create","delete","update","watch","patch","proxy"]
+			
+	Create a Role 
+		apiVersion: rbac.authorization.k8s.io/v1
+		kind: Role
+		metadata:
+		  namepsace: default	
+		  name: test-role
+		rules:
+			- apiGroups: [""]
+			  resources: ["pods"]
+			  verbs: ["get", "watch", "list"]	
+
+ClusterRole 
+	- this is cluster wide role 
+	
+	Create a ClusterRole 
+		apiVersion: rbac.authorization.k8s.io/v1
+		kind: ClusterRole
+		metadata:
+		  name: test-cluster-role
+		rules:
+			- apiGroups: [""]
+			  resources: ["pods"]
+			  verbs: ["get", "watch", "list"]
+	
+			  	
+Rolebinding and ClusterRoleBiniding 
+	- This helps to attach a role to a subject (useraccount, serviceaccount or groups)
+	- The only differenece is that we use rolebinding to attach role to account and 
+	  clusterrolebinding to attach cluster role to account.
+	
+	- We use RoleBinding to bind a Role to a ClusterRole  
+	
+	RoleBinding	
+		apiVersion: rbac.authorization.k8s.io/v1
+		kind: RoleBinding
+		metadata:
+		  namespace: default
+		  name: read-pods
+		subjects:
+		- kind: ServiceAccount
+		  name: test
+		  namespace: default
+		roleRef:
+		  apiGroup: rbac.authorization.k8s.io
+		  kind: Role
+		  name: test-role 
+		  
+	ClusterRoleBiniding	  
+		apiVersion: rbac.authorization.k8s.io/v1
+		kind: ClusterRoleBinding
+		metadata:
+		  namespace: default
+		  name: read-pods
+		subjects:
+		- kind: ServiceAccount
+		  name: test
+		  namespace: default
+		roleRef:
+		  apiGroup: rbac.authorization.k8s.io
+		  kind: ClusterRole
+		  name: test-role  
+		  
+	To check the access 
+		kubectl auth can-i list pods --as=system:serviceaccount:<account_namesapce>:<account_name> 
+		
\ No newline at end of file

From 6c955a0b8db4b7b7ff41a0e603c2bd9b11d54922 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Tue, 7 Jun 2022 09:40:04 +0530
Subject: [PATCH 34/37] afinity, taints 07-June-22

---
 kubernetes.txt | 157 ++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 124 insertions(+), 33 deletions(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index eaeb52e..cb65024 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -990,37 +990,7 @@ Configmaps and Secrets
 									name: test-secret
 									key: dbpassword		
 		
-How to create a pod on a particular worker pod 
-	1. Node selector 
-		- Node selector is a way of binding pod to a worker node or nodes based on the 
-		  node labels.
-		- We cannot use any logical expresions type of selection.  
-	
-		create a label to worker node 
-			kubectl label node <node_name> <key>=<value>
-			
-		Use nodeSelector with the same label created to create pods in the same worker node
-			apiVersion: apps/v1
-			kind: Deployment
-			metadata:
-			  name: nginx-deployment
-			spec:
-			  replicas: 6
-			  selector:
-				matchLabels:
-				  app: ipapp
-			  template:
-				metadata:
-				  labels:
-					app: ipapp
-				spec:
-				  nodeSelector:
-					<key>: <value>
-				  containers:
-				  - name: nginx
-					image: nginx:latest
-					ports:
-					- containerPort: 80
+
 
 service-controller
 endpoint-controller
@@ -1106,7 +1076,6 @@ ClusterRole
 			  resources: ["pods"]
 			  verbs: ["get", "watch", "list"]
 	
-			  	
 Rolebinding and ClusterRoleBiniding 
 	- This helps to attach a role to a subject (useraccount, serviceaccount or groups)
 	- The only differenece is that we use rolebinding to attach role to account and 
@@ -1146,4 +1115,126 @@ Rolebinding and ClusterRoleBiniding
 		  
 	To check the access 
 		kubectl auth can-i list pods --as=system:serviceaccount:<account_namesapce>:<account_name> 
-		
\ No newline at end of file
+
+How to create a pod on a particular worker pod 
+	1. Node selector 
+		- Node selector is a way of binding pod to a worker node or nodes based on the 
+		  node labels.
+		- We cannot use any logical expresions type of selection.  
+	
+		create a label to worker node 
+			kubectl label node <node_name> <key>=<value>
+			
+		Use nodeSelector with the same label created to create pods in the same worker node
+			apiVersion: apps/v1
+			kind: Deployment
+			metadata:
+			  name: nginx-deployment
+			spec:
+			  replicas: 6
+			  selector:
+				matchLabels:
+				  app: ipapp
+			  template:
+				metadata:
+				  labels:
+					app: ipapp
+				spec:
+				  nodeSelector:
+					<key>: <value>
+				  containers:
+				  - name: nginx
+					image: nginx:latest
+					ports:
+					- containerPort: 80
+					
+	2. Node afinity and anti-afinity (Inter-pod affinity)
+		
+		Node affinity 
+			- nodeselector with logical expresions is affinity.
+			- using node affinity we can spread pod across worker nodes based on 
+			  CPU and RAM capacity(memory-intense mode), Availabilty zone (HA mode).
+			
+			- requiredDuringSchedulingIgnoredDuringExecution	
+				The scheduler can't schedule the pod untill unless the rule is met.
+				
+			- preferredDuringSchedulingIgnoredDuringExecution
+				The scheduler tries to fina a node matching the rule, If a matching node 
+				is not available then scheduler still schedules the pod in normal way.
+				
+			- IgnoredDuringExecution
+				If the node labels are changed after the scheduling of pod still the pod 
+                continues to run. 	
+			
+			spec: 
+				containers: 
+						........
+						
+				affinity: 
+					nodeAffinity:
+					  requiredDuringSchedulingIgnoredDuringExecution:
+						nodeSelectorTerms:
+						- matchExpressions:
+						  - key: kubernetes.io/os
+							operator: In
+							values:
+							- linux
+					  preferredDuringSchedulingIgnoredDuringExecution:
+					  - weight: 1
+						preference:
+						  matchExpressions:
+						  - key: label-1
+							operator: In
+							values:
+							- key-1
+					  - weight: 50
+						preference:
+						  matchExpressions:
+						  - key: label-2
+							operator: In
+							values:
+							- key-2
+				
+		node Anti-affinity (Inter-pod Affinity)
+			- This is used to define whether a given pod should or should not be 
+			  scheduled on a particular node based on conditional labels.	
+			
+			spec: 
+				containers: 
+						........
+						
+				affinity: 
+					nodeAntiAffinity:
+					  requiredDuringSchedulingIgnoredDuringExecution:
+						IfNotPresent:
+						- matchExpressions:
+						  - key: <label_key>
+							operator: In
+							values:
+							- <label_value>
+	
+	3. Taints and Tolerations
+		- Taints are used to repel the pods from a specific node.
+		- we can apply taints to worker nodes which tell scheduler to repel all the pods 
+		  except those pods which contains tolerations for the taint.
+		- 2 operators we can use Equal and Exists (If we use Exists, no value required)
+		
+		- We can check the effects also 
+			1) NoSchedule - This taint means unless a pod with toleration the scheduler 
+				will never schedule the pod.
+			2) NoExecute - To delete all the pods except some reuired pods we can use this.
+
+			To taint a worker node
+				kubectl taint nodes <node_name> <taint_key>=<taint_value>:<taint_effect>
+		
+			spec: 
+				tolerations:
+				  - key: env
+					value: test
+					effect: NoSchedule
+					operator: Equal
+				containers:
+				  - name: nginx
+					image: nginx:latest
+					ports:
+					- containerPort: 80

From 192103f99970df02494be58bb156063c8fc59e77 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Tue, 7 Jun 2022 09:52:55 +0530
Subject: [PATCH 35/37] count quota 07-June-22

---
 kubernetes.txt | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/kubernetes.txt b/kubernetes.txt
index cb65024..65f2ca6 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -1238,3 +1238,36 @@ How to create a pod on a particular worker pod
 					image: nginx:latest
 					ports:
 					- containerPort: 80
+
+Resource quotas and limits 
+	How to limit the number of pods to a namepsace ?
+	how to limit the memory to a pod ?
+	
+	Count quota 
+		- This quota is used to limit the max number of obejcts that we can have 
+		  in a namepsace.
+		syntax: 
+			count/<resource>.<group> for resources from non-core groups
+			count/<resource> for resources from the core group
+			
+		Below are the list of resources we can have count quota 
+			count/pods
+			count/persistentvolumeclaims
+			count/services
+			count/secrets
+			count/configmaps
+			count/replicationcontrollers
+			count/deployments.apps
+			count/replicasets.apps
+			count/statefulsets.apps
+			count/jobs.batch
+			count/cronjobs.batch
+			
+		ex: 
+			apiVersion: v1
+			kind: ResourceQuota
+			metadata:
+			   name: pod-count-quota
+			spec:
+			  hard:
+				 scount/pods: "2"
\ No newline at end of file

From 6a4ad8d5ca4041cd0855c86e8941394911a62758 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Wed, 8 Jun 2022 09:56:42 +0530
Subject: [PATCH 36/37] Jobs, Deployment stratergy 08-June-22

---
 kubernetes.txt | 239 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 238 insertions(+), 1 deletion(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index 65f2ca6..f2c2ff1 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -1270,4 +1270,241 @@ Resource quotas and limits
 			   name: pod-count-quota
 			spec:
 			  hard:
-				 scount/pods: "2"
\ No newline at end of file
+				 scount/pods: "2"
+				 
+	Quota on CPU/RAM/Disk
+		apiVersion: v1
+		kind: ResourceQuota
+		metadata:
+		   name: resource-quota
+		spec:
+		  hard:
+			 request.cpu: "0.2"
+			 limits.cpu: "0.8"
+			 
+					0r 
+					
+			 request.memory: "512Mi"
+			 limits.memory: "800Mi"	
+		
+		CPU 
+		  - 1 cpu, in k8s 1 is equal to 100% to 1 cpu/core and 1 hyperthread.
+		  - if not specified by deafult k8s allocates 0.5 cpu to a pod.
+	
+				we can have 0.1, 0.2, ..... 0.9, 1  
+				
+				0.1 cpu = 100m = 1 hundred milli cpu
+		
+		Memory 
+			- In k8s resources are measured in bytes. 
+			- The memory should in simple integer value (Fixed point number).
+			- Representation Ki,Mi,Gi,Ti,Pi,Ei
+					
+			apiVersion: v1
+			kind: Pod
+			metadata:
+			  name: nginx-deployment-new
+			spec:
+			    containers:
+				  - name: nginx
+					image: nginx:1.14.2
+					ports:
+					- containerPort: 80	
+				resources:
+					requests: 
+						memory: "100Mi"
+						cpu: 0.5
+					limits:
+						memory: "250Mi"
+						cpu: 1
+
+- The main function of a job is to create one or more pods and tracks the success 
+	  status of pods.
+	- Jobs ensure that the specified number of pods is completed successfully and 
+	  when the job is completed pods go to the shutdown state and Job goes to completed state. 
+    - Mainly we use jobs to run pod temporarily till the task is completed and to run 
+	  tasks parallely.	
+	  
+	  apiVersion: batch/v1
+	  kind: Job
+	  metadata:
+	    name: my-job
+	  spec:
+	    template:
+	  	spec:
+	  	  containers:
+	  	  - name: busybox
+	  		image: busybox
+	  		command: ["echo", "This is first job"]
+	  	  restartPolicy: Never
+
+	restartPolicy 
+		- This is applied to pod not for the Job.
+		- There are values,
+			1. Always 
+			   - This is the default restart policy containers will always be restarted if they stop, 
+			     even if they completed successfully. 
+			   - This policy should be used for applications that always needs to be running.
+			2. OnFailure
+			   	  - will always restart containers only if the container process exits with an error code.
+				  - If the container is determined to be unhealthy by a liveness probe it will be restarted.
+				  - we use this policy for applications that need to run successfully & then stop.
+			3. Never
+				  - The pod’s containers will never be restarted, even if the container exits with error code 
+				    or a liveness probe fails. 
+	The different type of jobs or common parameters are,
+	
+	Completions
+		- This is the number of times the job to run. default is 1.
+		- If, completions is 5 then job will run 5 times means 5 pods.
+	  apiVersion: batch/v1
+	  kind: Job
+	  metadata:
+	    name: my-job
+	  spec:
+	  completions: 5
+	    template:
+	  	spec:
+	  	  containers:
+	  	  - name: busybox
+	  		image: busybox
+	  		command: ["echo", "This is first job"]
+	  	  restartPolicy: Never	
+
+	parallelism
+		- By default jobs run serialy so to run jobs parallely we need to use the parallelism.
+		- parallelism is used to set the number of job that need to run prallely.
+		
+	  apiVersion: batch/v1
+	  kind: Job
+	  metadata:
+	    name: my-job
+	  spec:
+	  completions: 5
+	  parallelism: 2
+	    template:
+	  	spec:
+	  	  containers:
+	  	  - name: busybox
+	  		image: busybox
+	  		command: ["echo", "This is first job"]
+	  	  restartPolicy: Never
+
+	backoffLimit
+		- If the container is failing for some reason which affects the completion the job,
+		  then still job creates more pods one after another until it succeeds which will 
+		  simply put a load on the cluster, in this case backoffLimit is used.
+		-  backoffLimitlimit ensure the number pods to limit after failure.
+		- backoffLimit: 2, once pods fails for 2 times it won’t create more pods.
+	  
+	  apiVersion: batch/v1
+	  kind: Job
+	  metadata:
+	    name: my-job
+	  spec:
+	  backoffLimit: 2
+	    template:
+	  	spec:
+	  	  containers:
+	  	  - name: busybox
+	  		image: busybox
+	  		command: ["sleep", "60"]
+	  	  restartPolicy: Never	
+
+	activeDeadlineSecond
+		- This is used to set the execution time for pod and if pod takes more than this 
+		  deadline time then pods will be terminated automatically.
+
+	  apiVersion: batch/v1
+	  kind: Job
+	  metadata:
+	    name: my-job
+	  spec:
+	  activeDeadlineSecond: 20
+	    template:
+	  	spec:
+	  	  containers:
+	  	  - name: busybox
+	  		image: busybox
+	  		command: ["sleep", "60"]
+	  	  restartPolicy: Never
+		  
+	Scheduled / CronJob
+		apiVersion: batch/v1
+		kind: CronJob
+		metadata:
+		  name: hello
+		spec:
+		  schedule: "* * * * *"
+		  jobTemplate:
+			spec:
+			  template:
+				spec:
+				  containers:
+				  - name: hello
+					image: busybox:1.28
+					imagePullPolicy: IfNotPresent
+					command:
+					- /bin/sh
+					- -c
+					- date; echo Hello from the Kubernetes cluster
+				  restartPolicy: OnFailure
+		
+		1. SuccessfulJobHistoryLimit and FailedJobHistoryLimit
+			apiVersion: batch/v1
+			kind: CronJob
+			metadata:
+			  name: hello
+			spec:
+			  schedule: "* * * * *"
+			  successfulJobHistoryLimit: 2
+			  failedJobHistoryLimit: 1
+			  jobTemplate:
+				spec:
+				  template:
+					spec:
+					  containers:
+					  - name: hello
+						image: busybox:1.28
+						imagePullPolicy: IfNotPresent
+						command:
+						- /bin/sh
+						- -c
+						- date; echo Hello from the Kubernetes cluster
+					  restartPolicy: OnFailure
+					  
+Deployment stratergies.	
+	Rolling Update 
+		- By default deployment in k8s uses rolling update stratergy which means if I want use 
+		  this stratergy I don'nt need to specify any parameters in spec file. 
+		- Example: By default k8s automatically decides the percentage of keeing available pods.
+		  usually one out 4 it updates. 
+		
+		- To overrride the default behaviour 
+			spec: 
+				stratergy: 
+					type: RollingUpdate 
+					rollingUpdate: 
+						maxSurge: 1
+						maxUnavailable: 25%
+			
+	Recreate 
+		The Recreate stratergy will bring all the old pods down immediately and the creates 
+		new updated pods to match the replica count.
+			spec: 
+				stratergy: 
+					type: Recreate 
+					
+	Blue/Green deployment
+		- We keep 2 sets of similar environment in which one will be live called blue  
+		  environment and the one which is not live is called as green. 
+		- we update the new changes to blue environment first which is not live and we 
+		  swap/ redirect the traffic from blue to green environment.
+		- Finally blue environment with new updates will become live and we rename it as 
+		  the current new blue environment.
+	
+	Canary release 
+		- A canary release is a software testing technique used to reduce the risk of 
+		  introducing a new software version into production by gradually rolling out 
+		  the change to a small subgroup of users, before rolling it out to the entire 
+		  platform/infrastructure.
\ No newline at end of file

From a72b4f4a81356c747a1a7c6b6cecb4511c50f243 Mon Sep 17 00:00:00 2001
From: jaintpharsha <jaintpharsha@gmail.com>
Date: Thu, 9 Jun 2022 10:38:15 +0530
Subject: [PATCH 37/37] multi master, hpa vpa 09-June-22

---
 kubernetes.txt | 112 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 111 insertions(+), 1 deletion(-)

diff --git a/kubernetes.txt b/kubernetes.txt
index f2c2ff1..dd11a9a 100644
--- a/kubernetes.txt
+++ b/kubernetes.txt
@@ -1226,6 +1226,11 @@ How to create a pod on a particular worker pod
 
 			To taint a worker node
 				kubectl taint nodes <node_name> <taint_key>=<taint_value>:<taint_effect>
+			
+			To delete a taint from worker node
+				(Put a "-" at the end of the command) 
+				kubectl taint nodes <node_name> <taint_key>=<taint_value>:<taint_effect>-
+		
 		
 			spec: 
 				tolerations:
@@ -1507,4 +1512,109 @@ Deployment stratergies.
 		- A canary release is a software testing technique used to reduce the risk of 
 		  introducing a new software version into production by gradually rolling out 
 		  the change to a small subgroup of users, before rolling it out to the entire 
-		  platform/infrastructure.
\ No newline at end of file
+		  platform/infrastructure.
+		  
+Multi master cluster 	
+	What is the size of the k8s cluster ?
+		- we are manitaining different cluster for different environment
+		- we have one big cluster and environments are maintained through namepsaces
+		- always the count of master nodes should a odd number 
+		- we are using loadbalancer / multiple people are working they may dd the worker nodes 
+		  so I never kept exact count of nodes but on average we have 20 to 25 worker nodes.
+	
+	Why always the number of master nodes is odd number ?
+		- Based on Quoram calculation (n/2+1) we get same quoram failure rate for odd number 
+		  and its next even number of nodes, so it is better to use odd number nodes instead 
+		  of even number and we start with minimum 3 master nodes.
+		- Always tell odd number of nodes (any odd number starting with 3, 5, 7, 9)
+		- Based on the quorum value we choose only odd number of nodes starting with 3 to 
+		  achive better fault tollerance cluster.
+		   
+pod eviction 
+
+	- Kubernetes evict pods if the node resources are running out such as cpu, RAM and storage.
+	- Pod with failed state will be evicted first because they may not running but could still 
+	  be using cluster resources and then k8s runs decision making based.
+	  
+	  Kubernetes looks at two different reasons to make eviction decision: 
+			1. QoS (Quality of Service) class. 
+				For every container in the pod:
+				  - There must be a memory limit and a memory request.
+				  - The memory limit must equal the memory request.
+				  - There must be a CPU limit and a CPU request.
+				  - The CPU limit must equal the CPU request.
+			2. Priority class.
+				- A pod's priority class defines the importance of the pod compared to other 
+				  pods running in the cluster.
+				- based on the priority low to high pods will be evicted.  
+
+k8s AutoScale			
+	Horizontal autoscaler 
+		Horizontal Pod Auto-Scaler (HPA)
+			- HPA is used to automatically scale the number of pods based on deployments, replicasets, 
+			  statefulsets or other objects, based on CPU, Memory threshold.
+			- Automatic scaling of the horizontal pod does not apply to objects that cannot be scaled.
+			  ex: DaemonSets.
+			- We need metric server as a soruce for autoscalling.
+
+			Metric server 
+				- Metrics Server collects resource metrics from Kubelets and exposes them in Kubernetes 
+				  API server through Metrics API for use by Horizontal Pod Autoscaler and Vertical Pod Autoscaler.
+				- kubectl top command use Metrics API to list the resource utilization of all pods. 
+				- Metrics Server is not meant for non-autoscaling purposes like we wont forward these metrics 
+				  data to monitoring tools. 
+				  
+			apiVersion: autoscaling/v2beta2
+			kind: HorizontalPodAutoscaler
+			metadata:
+			  name: php-apache-hps
+			spec:
+			  scaleTargetRef:
+				apiVersion: apps/v1
+				kind: Deployment
+				name: php-apache
+			  minReplicas: 1
+			  maxReplicas: 10
+			  metrics:
+			  - type: Resource
+				resource:
+				  name: cpu
+				  target:
+					type: Utilization
+					averageUtilization: 50 
+					
+				---------------- or ----------------
+				
+			kubectl autoscale deployment php-apache — cpu-percent=50 — min=1 — max=10		
+			
+			To list HPA 
+				kubectl get hpa
+			
+			
+		Vertical Pod Auto-Scaler (VPA)	   
+		    - vpa automatically adjusts the CPU and Memory attributes for your Pods.
+			- basically vpa will recreate your pod with the suitable CPU and Memory attributes.
+			- when we describe vpa, it will show recommendations for the Memory/CPU requests, Limits and it can also automatically 
+			  update the limits.
+		  
+		apiVersion: autoscaling.k8s.io/v1
+		kind: VerticalPodAutoscaler
+		metadata:
+		  name: my-app-vpa
+		spec:
+		  targetRef:
+			apiVersion: "apps/v1"
+			kind:       Deployment
+			name:       my-app
+		  updatePolicy:
+			updateMode: "Auto"  
+			
+			
+		Horizontal / Vertical Cluster Auto-Scaler		
+		  - Cluster Autoscaler is a tool that automatically adjusts the size of the Kubernetes 
+			cluster when one of the following conditions is true:
+				1. some pods failed to run in the cluster due to insufficient resources,
+				2. some nodes in the cluster that have been overloaded for an 
+				   extended period and their pods can be placed on other existing nodes.
+				   
+		  - Cluster autoscaller tools are mostly provided by public cloud providers.	
\ No newline at end of file