In today's world of containerized applications, Kubernetes has emerged as the de facto standard for container orchestration. Deploying and managing Kubernetes clusters manually can be complex and time-consuming. Thankfully, automation tools like Ansible provide a powerful way to automate the installation and configuration of Kubernetes clusters.
In this blog post, we'll explore how to use Ansible to automate the installation of a Kubernetes cluster. We'll walk through the steps involved in setting up Ansible, creating playbooks, and deploying Kubernetes on a set of target servers.
SETUP
Ansible Node ansible.mylabserver.com
Master Node master.mylabserver.com
Worker Nodes worker1.mylabserver.com
worker2.mylabserver.com
Prerequisite
1) Ansible must be installed on all the nodes
2) Set Password less authentication between Ansible Node to Master and Worker Nodes
Lets Create Playbook
Create ansible.cfg
root@06432e7f921c:~#mkdir k8s-install
root@06432e7f921c:~#cd k8s-install
root@06432e7f921c:~/k8s-install#cat ansible.cfg
[defaults]
inventory=./inventory
deprecation_warnings=False
Create Inventory File
root@06432e7f921c:~/k8s-install# cat inventory
[master]
master.mylabserver.com
[worker]
worker1.mylabserver.com
worker2.mylabserver.com
Verify they are accessible from Ansible Node
root@06432e7f921c:~/k8s-install# ansible -i inventory -m ping all
worker1.mylabserver.com | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python"
},
"changed": false,
"ping": "pong"
}
worker2.mylabserver.com | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python"
},
"changed": false,
"ping": "pong"
}
master.mylabserver.com | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python"
},
"changed": false,
"ping": "pong"
}
Create main.yaml file
root@06432e7f921c:~/k8s-install# cat main.yaml
---
- hosts: [master,worker]
gather_facts: false
roles:
- role: k8s-config
tags: common
- hosts: [master]
gather_facts: false
roles:
- role: master-config
tags: master
- hosts: [worker]
gather_facts: false
roles:
- role: worker-config
tags: worker
Create Role
root@06432e7f921c:~/k8s-install# ansible-galaxy init k8s-config
root@06432e7f921c:~/k8s-install# ansible-galaxy init master-config
root@06432e7f921c:~/k8s-install# ansible-galaxy init worker-config
Create Playbook for Common Installation
root@06432e7f921c:~/k8s-install# cat roles/k8s-config/tasks/main.yml
---
- name: Disable swap
command: swapoff -a
ignore_errors: yes
- name: Remove swap entry from /etc/fstab
lineinfile:
path: /etc/fstab
state: absent
regexp: '^.*swap.*$'
- name: Stop firewalld service
service:
name: ufw
state: stopped
enabled: no
- name: Ensure overlay and br_netfilter are present in containerd.conf
lineinfile:
path: /etc/modules-load.d/containerd.conf
line: "{{ item }}"
create: yes
loop:
- overlay
- br_netfilter
- name: Load Kernel modules
modprobe:
name: "{{ item }}"
loop:
- overlay
- br_netfilter
- name: Ensure kernel settings are present in kubernetes.conf
lineinfile:
path: /etc/sysctl.d/kubernetes.conf
line: "{{ item }}"
create: yes
loop:
- "net.bridge.bridge-nf-call-ip6tables = 1"
- "net.bridge.bridge-nf-call-iptables = 1"
- "net.ipv4.ip_forward = 1"
- name: Apply kernel settings
command: sysctl --system
- name: Set DEBIAN_FRONTEND environment variable
shell:
cmd: export DEBIAN_FRONTEND=noninteractive
- name: Add Kubernetes GPG key
apt_key:
url: "https://packages.cloud.google.com/apt/doc/apt-key.gpg"
state: present
- name: Update apt repositories
apt:
update_cache: yes
- name: Install required packages
apt:
name: "{{ item }}"
state: present
loop:
- apt-transport-https
- ca-certificates
- curl
- gnupg
- lsb-release
- name: Ensure /etc/apt/keyrings directory exists
file:
path: /etc/apt/keyrings
state: directory
mode: '0755'
- name: Check if Docker repository file exists
stat:
path: /etc/apt/sources.list.d/docker.list
register: docker_repo_file
- name: Add Docker repository using echo
shell:
cmd: 'echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null'
when: docker_repo_file.stat.exists == false
- name: Run apt update
apt:
update_cache: yes
- name: Install containerd.io package
apt:
name: containerd.io
state: present
- name: Generate default containerd configuration
command:
cmd: containerd config default > /etc/containerd/config.toml
- name: Set SystemdCgroup to true in containerd configuration
replace:
path: /etc/containerd/config.toml
regexp: 'SystemdCgroup\s*=\s*false'
replace: 'SystemdCgroup = true'
- name: Restart containerd service
service:
name: containerd
state: restarted
- name: Enable containerd service
service:
name: containerd
enabled: yes
- name: Download Kubernetes GPG key
shell:
cmd: curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.29/deb/Release.key | gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg --yes
- name: Add Kubernetes repository
copy:
content: |
deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.29/deb/ /
dest: /etc/apt/sources.list.d/kubernetes.list
- name: Update apt repositories
apt:
update_cache: yes
- name: Install Kubernetes components
apt:
name: "{{ item }}"
state: present
loop:
- kubeadm
- kubelet
- kubectl
Create Playbook to Create Cluster
root@06432e7f921c:~/k8s-install# cat roles/master-config/tasks/main.yml
---
- name: Initialize Kubernetes Cluster
shell:
cmd: "kubeadm init --apiserver-advertise-address=172.31.120.93 --pod-network-cidr=192.168.0.0/16 >> /root/kubeinit.log 2>/dev/null"
creates: /root/.kube/config
- name: Deploy Calico network
shell:
cmd: "kubectl --kubeconfig=/etc/kubernetes/admin.conf create -f https://raw.githubusercontent.com/projectcalico/calico/v3.27.0/manifests/tigera-operator.yaml && kubectl --kubeconfig=/etc/kubernetes/admin.conf create -f https://raw.githubusercontent.com/projectcalico/calico/v3.27.0/manifests/custom-resources.yaml"
creates: /etc/kubernetes/admin.conf
- name: Generate and save cluster join command to /joincluster.sh
shell:
cmd: "kubeadm token create --print-join-command > /joincluster.sh"
creates: /joincluster.sh
Create Playbook for worker node
root@06432e7f921c:~/k8s-install# cat roles/worker-config/tasks/main.yml
---
- name: Copy joincluster script to worker nodes
copy:
src: /joincluster.sh
dest: /joincluster.sh
mode: 0755
- name: Execute joincluster.sh script
shell:
cmd: /joincluster.sh
Install Common packages on all the 3 nodes
root@06432e7f921c:~/k8s-install# ansible-playbook main.yaml --tags common
PLAY [master,worker] ************************************************************************************************************************************************************************
TASK [k8s-config : Disable swap] ************************************************************************************************************************************************************
changed: [worker1.mylabserver.com]
changed: [master.mylabserver.com]
changed: [worker2.mylabserver.com]
TASK [k8s-config : Remove swap entry from /etc/fstab] ***************************************************************************************************************************************
ok: [worker1.mylabserver.com]
ok: [master.mylabserver.com]
ok: [worker2.mylabserver.com]
TASK [k8s-config : Stop firewalld service] **************************************************************************************************************************************************
ok: [worker1.mylabserver.com]
ok: [master.mylabserver.com]
ok: [worker2.mylabserver.com]
TASK [k8s-config : Ensure overlay and br_netfilter are present in containerd.conf] **********************************************************************************************************
ok: [worker1.mylabserver.com] => (item=overlay)
ok: [master.mylabserver.com] => (item=overlay)
ok: [worker2.mylabserver.com] => (item=overlay)
ok: [worker1.mylabserver.com] => (item=br_netfilter)
ok: [master.mylabserver.com] => (item=br_netfilter)
ok: [worker2.mylabserver.com] => (item=br_netfilter)
TASK [k8s-config : Load Kernel modules] *****************************************************************************************************************************************************
ok: [worker1.mylabserver.com] => (item=overlay)
ok: [master.mylabserver.com] => (item=overlay)
ok: [worker2.mylabserver.com] => (item=overlay)
ok: [worker1.mylabserver.com] => (item=br_netfilter)
ok: [master.mylabserver.com] => (item=br_netfilter)
ok: [worker2.mylabserver.com] => (item=br_netfilter)
TASK [k8s-config : Ensure kernel settings are present in kubernetes.conf] *******************************************************************************************************************
ok: [worker1.mylabserver.com] => (item=net.bridge.bridge-nf-call-ip6tables = 1)
ok: [worker2.mylabserver.com] => (item=net.bridge.bridge-nf-call-ip6tables = 1)
ok: [master.mylabserver.com] => (item=net.bridge.bridge-nf-call-ip6tables = 1)
ok: [worker1.mylabserver.com] => (item=net.bridge.bridge-nf-call-iptables = 1)
ok: [worker2.mylabserver.com] => (item=net.bridge.bridge-nf-call-iptables = 1)
ok: [master.mylabserver.com] => (item=net.bridge.bridge-nf-call-iptables = 1)
ok: [worker1.mylabserver.com] => (item=net.ipv4.ip_forward = 1)
ok: [worker2.mylabserver.com] => (item=net.ipv4.ip_forward = 1)
ok: [master.mylabserver.com] => (item=net.ipv4.ip_forward = 1)
TASK [k8s-config : Apply kernel settings] ***************************************************************************************************************************************************
changed: [worker1.mylabserver.com]
changed: [master.mylabserver.com]
changed: [worker2.mylabserver.com]
TASK [k8s-config : Set DEBIAN_FRONTEND environment variable] ********************************************************************************************************************************
changed: [worker1.mylabserver.com]
changed: [master.mylabserver.com]
changed: [worker2.mylabserver.com]
TASK [k8s-config : Add Kubernetes GPG key] **************************************************************************************************************************************************
ok: [worker1.mylabserver.com]
ok: [master.mylabserver.com]
ok: [worker2.mylabserver.com]
TASK [k8s-config : Update apt repositories] *************************************************************************************************************************************************
changed: [worker1.mylabserver.com]
changed: [master.mylabserver.com]
changed: [worker2.mylabserver.com]
TASK [k8s-config : Install required packages] ***********************************************************************************************************************************************
ok: [worker1.mylabserver.com] => (item=apt-transport-https)
ok: [master.mylabserver.com] => (item=apt-transport-https)
ok: [worker2.mylabserver.com] => (item=apt-transport-https)
ok: [worker1.mylabserver.com] => (item=ca-certificates)
ok: [master.mylabserver.com] => (item=ca-certificates)
ok: [worker2.mylabserver.com] => (item=ca-certificates)
ok: [worker1.mylabserver.com] => (item=curl)
ok: [master.mylabserver.com] => (item=curl)
ok: [worker1.mylabserver.com] => (item=gnupg)
ok: [worker2.mylabserver.com] => (item=curl)
ok: [master.mylabserver.com] => (item=gnupg)
ok: [worker1.mylabserver.com] => (item=lsb-release)
ok: [worker2.mylabserver.com] => (item=gnupg)
ok: [master.mylabserver.com] => (item=lsb-release)
ok: [worker2.mylabserver.com] => (item=lsb-release)
TASK [k8s-config : Ensure /etc/apt/keyrings directory exists] *******************************************************************************************************************************
ok: [worker1.mylabserver.com]
ok: [worker2.mylabserver.com]
ok: [master.mylabserver.com]
TASK [k8s-config : Check if Docker repository file exists] **********************************************************************************************************************************
ok: [worker1.mylabserver.com]
ok: [master.mylabserver.com]
ok: [worker2.mylabserver.com]
TASK [k8s-config : Add Docker repository using echo] ****************************************************************************************************************************************
skipping: [master.mylabserver.com]
skipping: [worker2.mylabserver.com]
skipping: [worker1.mylabserver.com]
TASK [k8s-config : Run apt update] **********************************************************************************************************************************************************
changed: [worker1.mylabserver.com]
changed: [worker2.mylabserver.com]
changed: [master.mylabserver.com]
TASK [k8s-config : Install containerd.io package] *******************************************************************************************************************************************
changed: [worker1.mylabserver.com]
changed: [worker2.mylabserver.com]
changed: [master.mylabserver.com]
TASK [k8s-config : Generate default containerd configuration] *******************************************************************************************************************************
changed: [worker1.mylabserver.com]
changed: [master.mylabserver.com]
changed: [worker2.mylabserver.com]
TASK [k8s-config : Set SystemdCgroup to true in containerd configuration] *******************************************************************************************************************
ok: [worker1.mylabserver.com]
ok: [worker2.mylabserver.com]
ok: [master.mylabserver.com]
TASK [k8s-config : Restart containerd service] **********************************************************************************************************************************************
changed: [worker1.mylabserver.com]
changed: [master.mylabserver.com]
changed: [worker2.mylabserver.com]
TASK [k8s-config : Enable containerd service] ***********************************************************************************************************************************************
ok: [worker1.mylabserver.com]
ok: [master.mylabserver.com]
ok: [worker2.mylabserver.com]
TASK [k8s-config : Download Kubernetes GPG key] *********************************************************************************************************************************************
[WARNING]: Consider using the get_url or uri module rather than running 'curl'. If you need to use command because get_url or uri is insufficient you can add 'warn: false' to this command
task or set 'command_warnings=False' in ansible.cfg to get rid of this message.
changed: [master.mylabserver.com]
changed: [worker2.mylabserver.com]
changed: [worker1.mylabserver.com]
TASK [k8s-config : Add Kubernetes repository] ***********************************************************************************************************************************************
ok: [worker1.mylabserver.com]
ok: [master.mylabserver.com]
ok: [worker2.mylabserver.com]
TASK [k8s-config : Update apt repositories] *************************************************************************************************************************************************
changed: [worker1.mylabserver.com]
changed: [worker2.mylabserver.com]
changed: [master.mylabserver.com]
TASK [k8s-config : Install Kubernetes components] *******************************************************************************************************************************************
ok: [worker1.mylabserver.com] => (item=kubeadm)
ok: [master.mylabserver.com] => (item=kubeadm)
ok: [worker2.mylabserver.com] => (item=kubeadm)
ok: [worker1.mylabserver.com] => (item=kubelet)
ok: [master.mylabserver.com] => (item=kubelet)
ok: [worker2.mylabserver.com] => (item=kubelet)
ok: [worker1.mylabserver.com] => (item=kubectl)
ok: [worker2.mylabserver.com] => (item=kubectl)
ok: [master.mylabserver.com] => (item=kubectl)
Install Cluster On Master Node
root@06432e7f921c:~/k8s-install# ansible-playbook main.yaml --tags master
PLAY [master] *******************************************************************************************************************************************************************************
TASK [master-config : Initialize Kubernetes Cluster] ****************************************************************************************************************************************
changed: [master.mylabserver.com]
TASK [master-config : Deploy Calico network] ************************************************************************************************************************************************
changed: [master.mylabserver.com]
TASK [master-config : Generate and save cluster join command to /joincluster.sh] ************************************************************************************************************
changed: [master.mylabserver.com]
PLAY RECAP **********************************************************************************************************************************************************************************
master.mylabserver.com : ok=26 changed=12 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
Install Cluster On Worker Node
root@06432e7f921c:~/k8s-install# ansible-playbook main.yaml --tags worker
PLAY [worker] *******************************************************************************************************************************************************************************
TASK [worker-config : Copy joincluster script to worker nodes] ******************************************************************************************************************************
ok: [worker1.mylabserver.com]
ok: [worker2.mylabserver.com]
TASK [worker-config : Execute joincluster.sh script] ****************************************************************************************************************************************
changed: [worker1.mylabserver.com]
changed: [worker2.mylabserver.com]
PLAY RECAP **********************************************************************************************************************************************************************************
worker1.mylabserver.com : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
worker2.mylabserver.com : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
Create a .kube file and copy admin to .kube dir
root@06432e7f921c:~/k8s-install# mkdir /root/.kube
root@06432e7f921c:~/k8s-install# cp /etc/kubernetes/admin.conf /root/.kube/config
Lets Verify Cluster Configured properly
root@06432e7f921c:~/k8s-install# kubectl get nodes
NAME STATUS ROLES AGE VERSION
master.mylabserver.com Ready control-plane 54m v1.29.3
worker1.mylabserver.com Ready <none> 43m v1.29.3
worker2.mylabserver.com Ready <none> 43m v1.29.3
Conclusion Automating the installation of Kubernetes using Ansible can significantly simplify the process and reduce the chance of errors. With Ansible playbooks, we can quickly provision and configure Kubernetes clusters on any infrastructure, whether it's on-premises or in the cloud.
In this blog post, we've only scratched the surface of what's possible with Ansible. As you become more familiar with Ansible and Kubernetes, you can further customize your playbooks to meet your specific requirements and integrate additional automation tasks.
Happy automating!
