Deploying Kubernetes objects using Ansible playbook

  • In this post I will walk you through on how to deploy/un-deploy Kubernetes objects using Ansible playbook

Pre-requisites

  • Setup Ansible control machine (from where scripts will be run)
  • Define user and SSH key
  • Allow user for for sudo without password

What we will do

  • Create inventory file called "inventory.ini" in home directory or any other folder. Default location of inventory file in ''etc/ansible/hosts' when custom inventory file is not specified
  • Create "ansible.cfg" file and specify inventory file created in step above.
  • Create ansible playbook
  • Deploy namespace on Kubernetes using playbook

Create Inventory file

Create a file "inventory.ini" specifying the hosts info.
[master]
K8s-master kubernetes_role=master


[workers]
K8s-worker1 kubernetes_role=node
K8s-worker2 kubernetes_role=node

Create "ansible.cfg file"

In the same folder where "inventory.ini" is created, create a file "ansible.cfg" and specify the below...

[defaults]
remote_user = <specify_user_with_SSH_setup>
host_key_checking = false
ask_pass = no
inventory = inventory.ini
interpreter_python = auto_legacy_silent

[privilege_escalation]
become = yes
become_ask_pass = no
become_method = sudo
become_user = root

Test the setup by trying to ping the hosts : 

    ansible all -m ping 


The k8s module requires the OpenShift Python client to communicate with the Kubernetes API. So before using the k8s role, you need to install the client. Since it’s installed with pip, we need to install Pip as well.

Create file ‘InstallAnsibleK8sModule.yaml’ with the below content

- hosts: K8s-master

  pre_tasks:
    - name: Ensure Pip is installed.
      package:
        name: python3-pip
        state: present

    - name: Ensure OpenShift client is installed.
      pip:
        name: openshift
        state: present

To run playbook

ansible-playbook InstallAnsibleK8Module.yaml

Deploying kubernetes objects can be achieved in 2  ways...

  • Create a playbook 'CreateNameSpace.yaml'

Specify the task to run from yaml file.
- hosts: k8s-master

  pre_tasks:
    - name: Ensure Pip is installed.
      package:
        name: python3-pip
        state: present

    - name: Ensure OpenShift client is installed.
      pip:
        name: openshift
        state: present
  tasks:
    - name: Creating Demo namespace by applying YAML definition file.
      k8s:
       state: present
       definition: "{{ lookup('file', 'demo-namespace.yaml') | from_yaml }}"

  • Specify the task to run from inline specification.
- hosts: k8s-master
  
  pre_tasks:
    - name: Ensure Pip is installed.
      package:
        name: python3-pip
        state: present

    - name: Ensure OpenShift client is installed.
      pip:
        name: openshift
        state: present
  tasks:
    - name: Creating DEMO namespace by applying inline definition.
      k8s:
        state: present
        definition:
          apiVersion: v1
          kind: Namespace
          metadata:
            name: demo-system
            labels:
             app: demo 
 
To run playbook

ansible-playbook CreateNamespace.yaml

Un-deploying kubernetes object...

To remove the namespace, you can create another playbook ‘RemoveNamespace.yaml’ (which can be in-line or yaml file based) and set the state to absent
    state: absent

To run playbook
ansible-playbook RemoveNamespace.yaml 

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