Ansible 17. conditions in ansibles

⚙️ Ansible Conditionals Summary

• Conditionals are an Ansible feature that allows you to control the execution flow of playbook tasks based on declared conditions.

• Actions like database backups, system reboots, or user management can be triggered only when relevant conditions are true.

• Unnecessary tasks can be skipped based on conditions, improving playbook efficiency and reducing potential errors.

• Conditionals can be used to notify relevant teams only when changes related to their responsibilities occur, enhancing communication and accountability.

A very simple example is below:

[oracle@oel01db ansible-project]$ cat ./inventory/hosts

[db_servers]

192.168.0.156

[oracle@oel01db ansible-project]$

[oracle@oel01db ansible-project]$ cat ./playbooks/craate-user-not-exist.yml

---

- name: Create tom user only if missing

  hosts: all

  become: yes

  tasks:

    - name: Check if tom user exists

      command: id tom

      register: tom_check

      failed_when: false

      changed_when: false

    - name: Create tom user

      user:

        name: tom

        state: present

      when: tom_check.rc != 0

[oracle@oel01db ansible-project]$

[oracle@oel01db ansible-project]$ ansible-playbook -i ./inventory/hosts ./playbooks/craate-user-not-exist.yml

PLAY [Create tom user only if missing] ******************************************************************************************************************************************************************************************************

TASK [Gathering Facts] **********************************************************************************************************************************************************************************************************************

ok: [192.168.0.156]

TASK [Check if tom user exists] *************************************************************************************************************************************************************************************************************

ok: [192.168.0.156]

TASK [Create tom user] **********************************************************************************************************************************************************************************************************************

changed: [192.168.0.156]

PLAY RECAP **********************************************************************************************************************************************************************************************************************************

192.168.0.156              : ok=3    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

[oracle@oel01db ansible-project]$

Verification

[oracle@oel01db ansible-project]$ ansible all -i ./inventory/hosts -m command -a "id tom"

192.168.0.156 | CHANGED | rc=0 >>

uid=54322(tom) gid=54331(tom) groups=54331(tom)

[oracle@oel01db ansible-project]$

Even if we just use

- name: Create tom user

  user:

    name: tom

    state: present

Ansible will NOT fail if tom already exist, reason being 

The user module is idempotent.

Situation	What Ansible Does
User does NOT exist	Creates the user
User already exists	Does NOTHING (skips)

We used condition only for learning purpose , in this case condition is not really needed