Implement-First-Playbook.md

LAB: Implement First Playbook

This scenario shows:

• how to create ansible playbooks
• how to run "apt install" command in the playbook
• how to run "update" command in the playbook
• how to run "apt remove" command in the playbook
• how to run command according to distribution (when)

Prerequisite

• You should have a look following lab, nodes that are created in that LAB, are using in ansible commands
  • LAB: Multipass-SSH Configuration (Create Ansible Test Environment)

Steps

• Create playbook to install apache2 app on nodes

"Apt Install" command in the playbook

nano install_apache.yml
# copy followings:
---

- hosts: all
  become: true
  tasks:

  - name: install apache2 package
    apt:
      name: apache2

• Run playbook

ansible-playbook --ask-become-pass install_apache.yml

• Under Task "install apache2 package", status are changed, this means installing apache2 packet on the nodes successfully

• If you run again that command, it is seen that "ok" under the Task "install apache2 package", it means that there is no change

• When you enter the one of the nodes' IP on the browser, you can see that the apache2 server is installed on it

• If you enter "never-existed-tect-package" as apt name, you can see that it cannot install on the nodes, because it does not exist.

"Update" command in the playbook

• Add "apt update" and install other packages

---

- hosts: all
  become: true
  tasks:

  - name: update repository index
    apt:
      update_cache: yes

  - name: install apache2 package
    apt:
      name: apache2

  - name: add php support for apache
    apt:
      name: libapache2-mod-php

ansible-playbook --ask-become-pass install_apache.yml

• Add "state: latest" to install latest version of the app

---

- hosts: all
  become: true
  tasks:

  - name: update repository index
    apt:
      update_cache: yes

  - name: install apache2 package
    apt:
      name: apache2
      state: latest

  - name: add php support for apache
    apt:
      name: libapache2-mod-php
      state: latest

"Apt remove" command in the playbook

• Create "remove_apache.yml" to uninstall apps.
• Use "state:absent" to uninstall.

---

- hosts: all
  become: true
  tasks:

  - name: remove apache2 package
    apt:
      name: apache2
      state: absent

  - name: add php support for apache
    apt:
      name: libapache2-mod-php
      state: absent

ansible-playbook --ask-become-pass remove_apache.yml

• When browsing IP to see whether apache2 works or not, it is seen that apache2 server was uninstalled.

Command According to the Distribution ("when")

• Add 'when: ansible-distribution == "Ubuntu"' into the install_apache.yaml file
• With 'when', it is possible to install command on specific distro (e.g. Ubuntu, Centos)

---

- hosts: all
  become: true
  tasks:

  - name: update repository index
    apt:
      update_cache: yes
    when: ansible_distribution in ["Debian", "Ubuntu"]

  - name: install apache2 package
    apt:
      name: apache2
      state: latest
    when: ansible_distribution == "Ubuntu"

  - name: add php support for apache
    apt:
      name: libapache2-mod-php
      state: latest
    when: ansible_distribution == "Ubuntu"

• To get more information about the specific node.

ansible all -m gather_facts --limit 172.21.79.85 | grep ansible_distribution

• It is possible to use 'when' commands with other details (e.g. "ansible_distribution_version": "22.04")

• Adding new tasks for 'CentOS' distribution

---

- hosts: all
  become: true
  tasks:

  - name: update repository index
    apt:
      update_cache: yes
    when: ansible_distribution in ["Debian", "Ubuntu"]

  - name: install apache2 package
    apt:
      name: apache2
      state: latest
    when: ansible_distribution == "Ubuntu"

  - name: add php support for apache
    apt:
      name: libapache2-mod-php
      state: latest
    when: ansible_distribution == "Ubuntu"

  - name: update repository index
    dnf:
      update_cache: yes
    when: ansible_distribution == "CentOS"

  - name: install apache2 package
    dnf:
      name: httpd
      state: latest
    when: ansible_distribution == "CentOS"

  - name: add php support for apache
    dnf:
      name: php
      state: latest
    when: ansible_distribution == "CentOS"

Run:

ansible-playbook --ask-become-pass install_apache.yml

• Tasks that are defined for 'CentOS' are skipped

Reference

• https://www.youtube.com/watch?v=VANub3AhZpI&list=PLT98CRl2KxKEUHie1m24-wkyHpEsa4Y70&index=6