register, Tags and Blocks

Results, selection, recovery

register: stores a task's result in a variable (stdout, return code, changed status) for later tasks. Tags label tasks so you can run or skip subsets with --tags and --skip-tags. A block: groups tasks, and rescue: / always: sections give try/catch/finally behaviour for recoverable failures. Use changed_when: and failed_when: to tell Ansible what counts as a change or failure for command-style tasks.

Registered output, run

Running only the info tag shows the registered stdout of a harmless command.

ansible-playbook -i inventory.ini vars.yml --tags info

Output:

"out.stdout": "hello"

A block with rescue

If the risky task fails, the rescue task runs and the play continues. (Illustrative; not run here.)

- name: Deploy with rollback
  block:
    - name: Switch to new release
      ansible.builtin.command: /opt/app/switch_release.sh {{ release }}
  rescue:
    - name: Roll back to previous release
      ansible.builtin.command: /opt/app/switch_release.sh {{ previous_release }}
  always:
    - name: Record the attempt
      ansible.builtin.debug:
        msg: "deploy attempt finished"

Quick check: What does `--tags info` do?

• Runs only tasks tagged info
• Deletes tasks tagged info
• Skips tasks tagged info
• Encrypts tags