DevOps Classroomnotes 26/Jan/2023

Ansible roles

• Lets create a role for tomcat playbook.
• Refer Here for the changes done to refactor the tomcat playbook into a role.
• In roles main.yml is the default file that gets called, from there we can call many other yaml files using include_tasks Refer Here
• Refer Here for sample
• Ideal usage of role

---
- hosts: webservers
  roles:
    - common
    - role: foo_app_instance
      vars:
        dir: '/opt/a'
        app_port: 5000
    - role: foo_app_instance
      vars:
        dir: '/opt/b'
        app_port: 5001

• The tomcat role works with version v10.0.27 (add this to variables). The other possible fix is to make the whole url as a variable.

Ansible Collections

• In Ansible the reusable assets are
  • roles
  • modules
• In Ansible we can create custom modules as well by writing python code.
• Ansible collections are collections of
  • custom ansible modules
  • roles
• Refer Here for the collections created.

Things to discuss

• facts (custom facts)
• inventory
  • static
  • dynamic
• flush handlers
• parallelism
• gather_facts
• Ansible on windows.
• ansible tower.

Setting custom facts

• Refer Here for the official docs

---
- name: setting some fact
  become: yes
  hosts: all
  tasks:
    - name: set some facts
      ansible.builtin.set_fact:
        message: This is from ansible
        team: devops
    - name: get the facts
      ansible.builtin.debug:
        msg: "The facts are team = {{ team }} message = {{ message }}" 

Flushing Handlers

• Ansible handlers are executed based on consolidataion of all the tasks in ansible.
• If you want to execute handlers after some step immedietly we use flush_handlers as mentioned below

---
- name: flush handlers demo
  hosts: all
  tasks:
    - name: print something
      ansible.builtin.file:
        path: "/tmp/handle1"
        state: touch
      notify:
        - handle1
        - handle2
    - name: Force all notified handlers to run at this point, not waiting for normal sync points
      ansible.builtin.meta: flush_handlers
    - name: print something again
      ansible.builtin.file:
        path: "/tmp/handle2"
        state: touch
      notify:
        - handle1
        - handle2
  handlers:
    - name: handle1
      ansible.builtin.debug:
        msg: "handle1"
    - name: handle2
      ansible.builtin.debug:
        msg: "handle2"