Ansible 23. error handling Block/Rescue/Always

The Block/Rescue/Always structure provides the most robust and controlled way to handle failures in Ansible, often referred to as a "try/catch/finally" mechanism.

✅ Basic Example: Block / Rescue / Always

- name: Demonstrate block, rescue, always
  hosts: all
  tasks:

    - block:
        - name: Try to run a command that fails
          ansible.builtin.command: /bin/false     # This always fails

        - name: This will not run
          ansible.builtin.debug:
            msg: "This won't run because previous task failed."

      rescue:
        - name: Run when block fails
          ansible.builtin.debug:
            msg: "Block failed! Running rescue section."

      always:
        - name: Run always
          ansible.builtin.debug:
            msg: "This task runs whether block fails or not."


How it works.
1️⃣ block:
Contains tasks that you expect might fail.
If all tasks succeed → rescue is not triggered.
If any task fails → rescue is triggered.

2️⃣ rescue:
Runs only if block fails.
Used for:
cleanup
alternative action
error logging
fallback/rollback operations


3️⃣ always:
Runs every time, whether success or failure.
Used for:
closing connections
cleanup
notifications
reporting


block / rescue is used when a task may fail and you want to execute alternative logic in response to that failure. 
This pattern is also commonly used to attempt a change inside the block, and if the change fails, automatically 
run rollback or recovery actions in the rescue section.