Ansible - Playbooks

Launch a playbook with commands like these:

ansible-playbook my_playbook.yaml          # run a playbook
ansible-playbook test.yaml -kK             # prompt for SSH pass and sudo pass

ansible-playbook playbook.yml --list-hosts  # show hosts that would be effected
ansible-playbook test.yaml --limit host1    # limit to specified host
ansible-playbook playbook.yml -f 10         # with more options ( 10 forks )

• NOTE - Spacing and indentation in playbooks is very important.

Basic playbook example:

test-task1.yaml


---
- name: A Test Playbook
  hosts: all
  tasks:
    - name: First Test
      command: "uname -a"

Playbook to install an NGINX web server and deploy a web page from a template:

web_deploy.yaml


---
- name: A Test Playbook
  hosts: webservers
  become: yes
  vars:
    var1: "TEST STRING 123ABC"
  tasks:

    - name: Update repo cache and install nginx package
      ansible.builtin.apt:
        name: nginx
        update_cache: yes

    - name: Make sure a service is started, enabled, and not masked
      ansible.builtin.systemd:
        state: started
        name: nginx
        enabled: true
        masked: no

    - template:
        src: templates/index.html.j2
        dest: /var/www/html/index.html
        mode: a+r

Big example showing multiple different options and different ways to define and import variables:

db_deploy.yaml


- name: Update db servers
  hosts: databases
  remote_user: admin
  become: yes
  vars:
    trigger_task: true
    supported_os:
      - RedHat
      - Fedora
  vars_files:
    - my_variables.yaml
    - db_params.yaml
  gather_facts: false

  tasks:

  - name: Include Variables
    include_vars: "my_variables2.yaml"

  - name: Ensure postgresql is at the latest version
    ansible.builtin.yum:
      name: postgresql
      state: latest

  - name: Ensure that postgresql is started
    ansible.builtin.service:
      name: postgresql
      state: started

Sections

Playbooks can be broken into different sections. They are run in this order:

• pre_tasks
• fact gathering
• roles
• tasks
• post_tasks

Handlers run after each of those stages. ( more on handlers and roles in later sections )

Here is an example of how this can be split up:

test_sections.yaml


---
- name: A Test Playbook
  hosts: webservers
  become: yes


  pre_tasks:

    - name: Test task
      command: "import_data"

  tasks:

    - name: Test task
      command: "process_data"
    - name: Test task
      command: "move_data"

  post_tasks:

    - name: Test task
      command: "export_data"
    - name: Test task
      command: "cleanup_data"

Ansible - Multiple Plays

Breaking a playbook into multiple plays allows you to specify differnt sets of hosts and a different remote_user for each play.

test_multi.yaml


---
- hosts: webservers
  remote_user: user1

  tasks:
  - name: ensure nginx is at the latest version
    apt:
      name: nginx
      state: latest

- hosts: databases
  remote_user: admin

  tasks:
  - name: ensure postgresql is at the latest version
    apt:
      name: postgresql
      state: latest

Verify

Verify playbooks ( I rarely use this but you might want to ):

ansible-playbook test.yaml --check
ansible-playbook test.yaml --diff
ansible-playbook test.yaml --list-hosts
ansible-playbook test.yaml --list-tasks
ansible-playbook test.yaml --syntax-check