Blocks, Rescue, and Always¶

Why This Exists¶

A flat task list has no concept of "if any of these three tasks fail, do this instead" — block/rescue/always is Ansible's answer, modeled loosely on try/except/finally from general-purpose languages, but evaluated per host.

What It Will Cover¶

• block: to group related tasks (shared when:, become:, tags applied once to the whole group)
• rescue: — runs only if a task inside the block fails; the failure is then considered handled unless rescue itself fails or explicitly re-raises
• always: — runs regardless of whether the block succeeded, failed, or was rescued
• ansible_failed_task / ansible_failed_result magic variables available inside rescue:
• A worked example: attempt a deployment in block, roll back in rescue, and always send a notification in always

Common Mistakes¶

• Assuming a failure inside rescue: itself is silently swallowed — it isn't; an unhandled failure there still fails the host.
• Forgetting always: runs even on a host that never entered rescue: (i.e., the block fully succeeded) — it isn't only for the failure path.

Interview Questions¶

• What's the difference between rescue: and always:?
• How would you implement a deployment rollback using block/rescue?

Next¶

Continue to Error Handling.