/kubernetes

KUBERNETES CLUSTER WITH KUBEADM & ANSIBLE

Primary LanguageShell

Create Kubernetes Cluster using kubeadm

Ansible playbook to create a Kubernetes cluster using "kubeadm" on systems with CentOS-7.x operating system.

There are different roles defined in this ansible playbook.

Role: "base" -- Base configuration for "all hosts":

- Create and insert all entry on file "hosts" for kubernetes servers (If you don't have a DNS Server configured) 

- Disable "SELinux"

- Disable "firewalld"

- Install "chronyd" for NTP synch

- Install "wget"

- Install "bash-completion"

Role: "master" -- Initial Kubernetes setup for "kubernetes-master" node

- Install Start and Enable "Docker"

- Install "Kubectl"

- Install Start and Enable "Kubelet"

- Install "Kubeadm"

Role: "edge" -- Initial Kubernetes setup for "kubernetes-edge" nodes

- Install Start and Enable "Docker"

- Install Start and Enable "Kubelet"

- Install "Kubeadm"

Role: "create_token" -- Create token needed for cluster initialization

- Generate token that will be used for Master node cluster inizialization and Edge nodes cluster join

Role: "configmaster" -- Configuration for "kubernetes-master" node

- Initialize master with kubeadm 

- Export env var for Kubernetes

- Install pod network "weave-kube 1.6"

Role: "configedge" -- Configuration for "kubernetes-edge" nodes

- Join Edge Nodes to cluster with kubeadm

Role: "dashboard" -- Add-on to kubernetes cluster

- Dashboard

Role: "Glusterfs" -- Add-on to kubernetes cluster

- Persistent Storage using GlusterFS

Following the below steps to create Kubernetes cluster.

Prerequisites:

  1. Main:

    a) One server with git and ansible software:

     - Ansible version 2.3.1.0

 - Git Version 1.8.3.1

    b) Kubernetes: N° 1 "Master" server

    c) Kubernetes: N° 1 or more "Edge" servers

    d) If you need persistent storage, add secondary disk to "Edge" servers

    e) Full network connectivity between Kubernetes servers and Ansible

    f) Ansible can ssh into all Server and can "sudo" with no password prompt

    g) Servers have access to Internet

    h) Servers are time-synchronized

  2. On Kubernetes servers:

    a) Create User "centos";

    b) Configure User "centos" in /etc/sudoers. Execute as root:

     echo "centos  ALL=(ALL)       NOPASSWD: ALL" >> /etc/sudoers

  3. On Ansible server:

    a) Install git:

    root@Ansible:~# yum install git-1.8.3.1-6.el7_2.1.x86_64 -y

    b) Install ansible:

    root@Ansible:~# yum install epel-release -y
root@Ansible:~# yum install ansible-2.3.1.0-1.el7.noarch -y

    c) Download "Kubernetes" playbook from Git repo:

    root@Ansible:~# cd /etc/ansible/
root@Ansible:~# git clone https://github.com/lorenzoeusepi77/kubernetes.git

    d) For "Kubernetes cluster setup" edit all necessary parameters in accordance with your
    environment in inventory file: "kubernetes/inventories/production/hosts"

    e) For "Add edge nodes to existing Kubernetes cluster" edit all necessary parameters in accordance with your
    environment in inventory file: "kubernetes/inventories/production/addedgehosts"

    f) For "configure persistent storage glusterfs for Kubernetes cluster" edit all necessary parameters in accordance with your environment in inventory file: "kubernetes/inventories/production/glusterfshosts"

    g) Create ssh key and copy an all Kubernetes servers (only if you use password authentication for servers):

    root@Ansible:~# ssh-keygen
root@Ansible:~# ssh-copy-id centos@"MasterServerIP"
root@Ansible:~# ssh-copy-id centos@"Edge1ServerIP"
root@Ansible:~# ssh-copy-id centos@"Edge2ServerIP"
root@Ansible:~# ssh-copy-id centos@"Edge3ServerIP"

    h) Disable StrictHostKeyChecking:

    root@Ansible:~# cp /etc/ansible/kubernetes/cfg/ansible/file/config /root/.ssh/

Create Kubernetes cluster with Kubeadm

Run Ansible playbook with "kubernetes" as clustername and "centos" as user for your servers.

You need to change vars according with your environment on inventory file:

   [root@ansible ansible]# vi /etc/ansible/kubernetes/inventories/production/hosts

Execute playbook:

   root@Ansible:~# cd /etc/ansible/

   root@Ansible:~# ansible-playbook -i kubernetes/inventories/production/hosts kubernetes/site-create_cluster.yml -e clustername=kubernetes -u centos


   Note: If you use ssh key add:

   --private-key key.pub 

   The key must have this access permission     root@Ansible:~# chmod 400 key.pub

Add "edge nodes" to Kubernetes cluster

Run Ansible playbook with "kubernetes" as clustername and "centos" as user for your servers.

You need to change vars according with your environment on inventory file:

   [root@ansible ansible]# vi /etc/ansible/kubernetes/inventories/production/hosts

Execute playbook:

   root@Ansible:~# cd /etc/ansible/

   root@Ansible:~# ansible-playbook -i kubernetes/inventories/production/addedgehosts kubernetes/site-add_edgenode.yml -e clustername=kubernetes -u centos


   Note: If you use ssh key add:

   --private-key key.pub 

   The key must have this access permission     root@Ansible:~# chmod 400 key.pub

Add "GlusterFS" to Kubernetes cluster as Persistent Storage Volume

Run Ansible playbook with "kubernetes" as clustername and "centos" as user for your servers.

You need to change vars according with your environment on inventory file:

   [root@ansible ansible]# vi /etc/ansible/kubernetes/inventories/production/glusterfshosts

Execute playbook:

   root@Ansible:~# cd /etc/ansible/

   root@Ansible:~# ansible-playbook -i kubernetes/inventories/production/glusterfshosts kubernetes/site-glusterfs.yml -e clustername=kubernetes -u centos


   Note: If you use ssh key add:

   --private-key key.pub 

   The key must have this access permission     root@Ansible:~# chmod 400 key.pub