Merge remote-tracking branch 'origin/checking_resources' into checking_resources

Author: chrisguest75

34_checking_resources/CGROUPS.md

@@ -0,0 +1,53 @@
+# README
+Demonstrate how to work with cgroups
+
+## cgroups 
+```sh
+# man pages
+man cgroups
+
+# list filesystems and look at cgroups
+cat /proc/filesystems  
+
+# see where they a virtually mounted
+mount
+```
+
+## Install tooling
+```sh
+# install tooling
+sudo apt install cgroup-tools        
+
+# list cgroup tools
+dpkg -L cgroup-tools | grep bin        
+
+```
+
+## Walk the filesystem
+```sh
+# cgroups v1
+ls /sys/fs/cgroup/
+
+# cgroups v2
+ls /sys/fs/cgroup/unified     
+```
+
+
+## Resources
+https://medium.com/nttlabs/cgroup-v2-596d035be4d7
+
+
+https://opensource.com/article/20/10/cgroups
+
+https://www.linuxjournal.com/content/everything-you-need-know-about-linux-containers-part-i-linux-control-groups-and-process
+
+https://www.linuxjournal.com/content/everything-you-need-know-about-linux-containers-part-ii-working-linux-containers-lxc
+
+
+SSH in a cgroup
+https://unix.stackexchange.com/questions/209199/how-to-ensure-ssh-via-cgroups-on-centos
+
+https://unix.stackexchange.com/questions/56538/controlling-priority-of-applications-using-cgroups
+
+cgroupsv2
+https://unix.stackexchange.com/questions/471476/how-do-i-check-cgroup-v2-is-installed-on-my-machine

37_checking_resources/README.md renamed to 34_checking_resources/README.md

@@ -3,6 +3,7 @@ Demonstrate how to use various commands to verify resource usage in the OS.
 
 
 TODO:
+* cgroups
 * Open sockets
 * Free memory 
 * File handles
@@ -12,6 +13,33 @@ TODO:
 * debugfs
 https://github.com/raboof/nethogs
 
+
+```sh
+# booted with
+cat /proc/cmdline 
+
+# built with
+cat /boot/config-5.8.0-49-generic | grep CGROUP
+
+# global limits
+systemctl show     
+```
+
+## Check limits
+```sh
+# limits inside a container
+docker run -it ubuntu:20.04 /bin/bash -c "ulimit -a" 
+
+# limits on host
+ulimit -a 
+
+# limits for current pid
+cat /proc/$$/limits 
+
+# show global config
+systemctl show    
+```
+
 ## Disk
 
 ```sh
@@ -22,9 +50,20 @@ df -h
 ## Sockets
 
 ```sh
+# summary of all the sockets
+ss -s 
+
 # listening sockets
 ss -l 
+
+# listening sockets with processes
+sudo ss -lp
+
+# tcp connections with information
+ss -ti 
 ```
+
+
 ## Memory
 
 ```sh

README.md

@@ -159,17 +159,21 @@ Steps [README.md](./32_jq/README.md)
 Demonstrates using awscli to query resources in an AWS account.  
 Steps [README.md](./33_awscli/README.md)  
 
+## Example 34 - Checking Resources
+Demonstrate how to use various commands to verify resource usage in the OS.
+Steps [README.md](./34_checking_resources/README.md) 
+
 ## Example 35 - APT and DPKG
 Demonstrate examples of working with APT and DPKG  
 Steps [README.md](./35_apt_and_dpkg/README.md)  
 
 ## Example 36 - Git Querying
-Demonstrates some examples of using git queries  
-Steps [README.md](./36_git_querying/README.md)  
+Demonstrates some examples of using git queries   
+Steps [README.md](./36_git_querying/README.md)   
 
 ## Example 37 - Checking Resources
-Demonstrate how to use various commands to verify resource usage in the OS.
-Steps [README.md](./37_checking_resources/README.md) 
+Demonstrate how to use various commands to verify resource usage in the OS.  
+Steps [README.md](./37_checking_resources/README.md)  
 
 ## TODO:
   * Globbing