Red Hat Enterprise Linux Automation with Ansible

Procedure 4.1. Instructions

1. On workstation.lab.example.com, change to the /home/student/control-flow project directory.

   [student@workstation ~]$ cd ~/control-flow
   [student@workstation control-flow]$

2. The lab script created an Ansible configuration file as well as an inventory file. This inventory file contains the server servera.lab.example.com in the database_dev host group, and the serverb.lab.example.com in the database_prod host group. Review the file before proceeding.

   [student@workstation control-flow]$ cat inventory
   [database_dev]
   servera.lab.example.com
   
   [database_prod]
   serverb.lab.example.com

3. Create the playbook.yml playbook, which contains a play with two tasks. Use the database_dev host group. The first task installs the MariaDB required packages, and the second task ensures that the MariaDB service is running.

   1. Open the playbook in a text editor. Define the variable mariadb_packages with two values: mariadb-server, and python3-PyMySQL. The playbook uses the variable to install the required packages. The file should read as follows:

      ---
      - name: MariaDB server is running
        hosts: database_dev
        vars:
          mariadb_packages:
            - mariadb-server
            - python3-PyMySQL

   2. Define a task that uses the yum module and the variable mariadb_packages. The task installs the required packages. The task should read as follows:

        tasks:
          - name: MariaDB packages are installed
            yum:
              name: "{{ item }}"
              state: present
            loop: "{{ mariadb_packages }}"

   3. Define a second task to start the mariadb service. The task should read as follows:

          - name: Start MariaDB service
            service:
              name: mariadb
              state: started
              enabled: true

4. Run the playbook and watch the output of the play.

   [student@workstation control-flow]$ ansible-playbook playbook.yml
   
   PLAY [MariaDB server is running] ***********************************************
   
   TASK [Gathering Facts] *********************************************************
   ok: [servera.lab.example.com]
   
   TASK [MariaDB packages are installed] ******************************************
   changed: [servera.lab.example.com] => (item=mariadb-server)
   changed: [servera.lab.example.com] => (item=python3-PyMySQL)
   
   TASK [Start MariaDB service] **************************************************
   changed: [servera.lab.example.com]
   
   PLAY RECAP *********************************************************************
   servera.lab.example.com    : ok=3    changed=2    unreachable=0    failed=0

5. Update the first task to execute only if the managed host uses Red Hat Enterprise Linux as its operating system. Update the play to use the database_prod host group. The task should read as follows:

   - name: MariaDB server is running
     hosts: database_prod
     vars:
   ...output omitted...
     tasks:
       - name: MariaDB packages are installed
         yum:
           name: "{{ item }}"
           state: present
         loop: "{{ mariadb_packages }}"
         when: ansible_distribution == "RedHat"

6. Verify that the managed hosts in the database_prod host group use Red Hat Enterprise Linux as its operating system.

   [student@workstation control-flow]$ ansible database_prod -m command \
   > -a 'cat /etc/redhat-release' -u devops --become
   serverb.lab.example.com | CHANGED | rc=0 >>
   Red Hat Enterprise Linux release 8.4 (Ootpa)

7. Run the playbook again and watch the output of the play.

   [student@workstation control-flow]$ ansible-playbook playbook.yml
   
   PLAY [MariaDB server is running] ***********************************************
   
   TASK [Gathering Facts] *********************************************************
   ok: [serverb.lab.example.com]
   
   TASK [MariaDB packages are installed] ******************************************
   changed: [serverb.lab.example.com] => (item=mariadb-server)
   changed: [serverb.lab.example.com] => (item=python3-PyMySQL)
   
   TASK [Start MariaDB service] ***************************************************
   changed: [serverb.lab.example.com]
   
   PLAY RECAP *********************************************************************
   serverb.lab.example.com    : ok=3    changed=2    unreachable=0    failed=0

   Ansible executes the task because serverb.lab.example.com uses Red Hat Enterprise Linux.