Setting up Kubernetes clusters

• Setting up Kubernetes clusters
  • Local cluster using Kubespray and Vagrant
    • Change base OS
    • Fixing connectivity issues with kube proxy and Vagrant
    • Starting the cluster
    • Administration
    • Deploy and run a sample voting app
    • Persistent storage
      • Create a storage class for local storage
      • Register local persistent volume
      • Claim storage on persistent volumes
    • Installing and configuring the Helm package manager
    • Using Terraform to manage resources on your cluster
    • Using kompose to translate Docker Compose files to Kubernetes
    • Using Kubeless to support serverless functions on your cluster

Local cluster using Kubespray and Vagrant

Refer to https://github.com/kubernetes-incubator/kubespray/ for more information.

$ git clone https://github.com/kubernetes-incubator/kubespray.git
$ cd kubespray

Change base OS

Change your base OS to CentOS.

$ echo "\$os = \"centos\"" >> vagrant/config.rb

Fixing connectivity issues with kube proxy and Vagrant

You will have issues with connecting to cluster services using kube proxy across multiple hosts.

You need to update the flannel configuration such that networking combined with Vagrant works properly.

Modify kubespray/inventory/sample/group_vars/k8s-cluster.yml and add the following variable.

flannel_interface: eth1

Starting the cluster

$ vagrant up

Administration

Also refer to https://kubernetes.io/docs/reference/kubectl/cheatsheet/ for more information.

Getting cluster information.

vagrant@k8s-01:~$ kubectl cluster-info
Kubernetes master is running at http://localhost:8080
KubeDNS is running at http://localhost:8080/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
kubernetes-dashboard is running at http://localhost:8080/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

Forwarding port 8001 on the host to 8001 on the guest

$ echo '$forwarded_ports = {8001 => 8001}' >> vagrant/config.rb
$ vagrant reload
$ vagrant provision

Setting up a proxy to the cluster on port 8001

$ vagrant ssh k8s-01
vagrant@k8s-01:~$ kubectl proxy --port=8001 --api-prefix=/ --address='0.0.0.0'

Give the dashboard admin access for development purposes.

Also refer to https://github.com/kubernetes/dashboard/wiki/Access-control for more information.

You can grant full admin privileges to Dashboard's Service Account by creating below ClusterRoleBinding. Copy the YAML file based on chosen installation method and save as, i.e. dashboard-admin.yaml. Use kubectl create -f dashboard-admin.yaml to deploy it. Afterwards you can use Skip option on login page to access Dashboard.

Browse to the dashboard at http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/#!/login and click on "Skip"

Note: don't use this configuration for production clusters because of the security risks!

Deploy and run a sample voting app

Please refer to sample-app.md for installing a sample voting app on your cluster.

Persistent storage

Create a storage class for local storage

A StorageClass provides a way for administrators to describe the “classes” of storage they offer. Different classes might map to quality-of-service levels, or to backup policies, or to arbitrary policies determined by the cluster administrators. Kubernetes itself is unopinionated about what classes represent. This concept is sometimes called “profiles” in other storage systems.

Also refer to https://kubernetes.io/docs/concepts/storage/storage-classes/

You can define a storage class for local storage by creating below StorageClass. Copy the YAML file based on chosen installation method and save as, i.e. local-sc.yaml. Use kubectl create -f local-sc.yaml to deploy it.

Register local persistent volume

You can allocate some space for persistent storage by creating below PersistentVolume. Copy the YAML file based on chosen installation method and save as, i.e. local-pv.yaml. Use kubectl create -f local-pv.yaml to deploy it.

Note: don't use this configuration for production clusters!

Also refer to https://kubernetes.io/docs/concepts/storage/persistent-volumes/

Claim storage on persistent volumes

You can claim some space for persistent storage by creating below PersistentVolumeClaim. Copy the YAML file based on chosen installation method and save as, i.e. local-pvc.yaml. Use kubectl create -f local-pvc.yaml to deploy it.

Installing and configuring the Helm package manager

Helm helps you manage Kubernetes applications — Helm Charts helps you define, install, and upgrade even the most complex Kubernetes application.

Charts are easy to create, version, share, and publish — so start using Helm and stop the copy-and-paste madness.

The latest version of Helm is maintained by the CNCF - in collaboration with Microsoft, Google, Bitnami and the Helm contributor community.

Also refer to https://docs.helm.sh/ for documentation.

In this case we'll installing Helm on one of the nodes. However, you're also able to install it on your host machine.

Please refer to helm.md for installing and configuring Helm

Using Terraform to manage resources on your cluster

While you could use kubectl or similar CLI-based tools mapped to API calls to manage all Kubernetes resources described in YAML files, orchestration with Terraform presents a few benefits.

Please refer to https://www.terraform.io/docs/providers/kubernetes/guides/getting-started.html for more information.

Please refer to terraform.md for managing resources using Terraform.

Using kompose to translate Docker Compose files to Kubernetes

kompose is a tool to help users who are familiar with docker-compose move to Kubernetes. kompose takes a Docker Compose file and translates it into Kubernetes resources.

kompose is a convenience tool to go from local Docker development to managing your application with Kubernetes. Transformation of the Docker Compose format to Kubernetes resources manifest may not be exact, but it helps tremendously when first deploying an application on Kubernetes.

Please refer to kompose.md for translating Docker Compose to Kubernetes.

Using Kubeless to support serverless functions on your cluster

Kubeless is a Kubernetes-native serverless framework that lets you deploy small bits of code (functions) without having to worry about the underlying infrastructure. It is designed to be deployed on top of a Kubernetes cluster and take advantage of all the great Kubernetes primitives.

Please refer to https://kubeless.io/ for more info.

Refer to kubeless.md for installing Kubeless and deploying sample serverless functions on your cluster.