Hello World with Jinja

Tip

We recommend to use the Sandbox to play around with this example.

Tip

All the files from this section are in hello-world-with-jinja.zip.

In Introduction, it was mentioned that inventory can contain variables. In this section, you will learn how to use variables from the inventory, vault, or command line in the playbook.

Note

Variables are passed to Ansible from the command line using --extra-vars.

Inventory

inventories/production.yml

web:
  hosts:
    managed_node_01:
      ansible_user: ansible
      ansible_password: '{{ managed_node_password }}'
      hello_world_text: Hello world!

The above inventory defines a variable named hello_world_text and uses a variable managed_node_password defined in the vault.

Playbook

playbook.yml

- name: My first play
  hosts:
    - web
  tasks:
   - name: Print message
     ansible.builtin.debug:
       msg: '{{ hello_world_text }}'

The above playbook uses the variable named hello_world_text defined in the inventory.

Important

The {{ variable_name }} is from Jinja.

Running

cd hello-world-with-jinja
--ask-vault-pass \
-i inventories/production.yml \
--extra-vars @vault/production \
playbook.yaml

Note

The password for the vault used in the example is 123. You must use a strong passwords, for example, a minimum of 8 randomly generated characters.

returns

PLAY [My first play] ***********************************************************

TASK [Gathering Facts] *********************************************************
ok: [managed_node_01]

TASK [Print message] ***********************************************************
ok: [managed_node_01] => {
    "msg": "Hello world!"
}

PLAY RECAP *********************************************************************
managed_node_01               : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Filters

Jinja allow the use of filters to modify the value of variables. You can use Jinja’s builtin filters, Ansible’s builtin filters, or your own custom filter. Filters are separated from the variable by a pipe symbol (|) and may have optional arguments in parentheses. Multiple filters can be chained.

Playbook

playbook.yml

- name: My first play
  hosts:
    - web
  tasks:
   - name: Print message
     ansible.builtin.debug:
       msg: '{{ hello_world_text | upper | truncate(6)  }}'

Running

cd hello-world-with-jinja
ansible-playbook \
--ask-vault-pass \
-i inventories/production.yml \
--extra-vars @vault/production \
playbook-with-filter.yaml

Note

The password for the vault used in the example is 123. You must use a strong passwords, for example, a minimum of 8 randomly generated characters.

returns

PLAY [My first play] ***********************************************************

TASK [Gathering Facts] *********************************************************
ok: [managed_node_01]

TASK [Print message] ***********************************************************
ok: [managed_node_01] => {
    "msg": "HEL..."
}

PLAY RECAP *********************************************************************
managed_node_01            : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0