Handler are task that are defined globally outside a play and can be called by the notify property in case of state change during task execution.
- Handlers by default get executed
- at the end of the playbook.
- only when the task has the changed status
- A handler would be called only once no matter how many times it was notified.
- Handler names and listen topics live in a global namespace.
- If two handler tasks have the same name, only one will run.
You cannot notify a handler that is defined inside of an include. As of Ansible 2.1, this does work, however the include must be static.
- The notify keyword add an handler to a set of handler (ie an handler is run only once by section)
- The set is flushed (processed) by default at the end of a section
- The executions occurs in the order defined in the handlers section (handlers are always run in the same order they are defined, not in the order listed in the notify-statement.)
Handlers notified within:
- pre_tasks, tasks, and post_tasks sections are automatically flushed in the end of section where they were notified;
- roles section are automatically flushed in the end of tasks section, but before any tasks handlers.
If you ever want to flush all the handler commands immediately you can do this:
tasks: - shell: some tasks go here - meta: flush_handlers - shell: some other tasks
In the above example any queued up handlers would be processed early when the meta statement was reached.
If the file template.j2 has changed, the memcached and apache services will be restarted.
# handlers definition handlers: - name: restart memcached service: name: memcached state: restarted listen: "restart web services" # group handlers in one call - name: restart apache service: name: apache state: restarted listen: "restart web services" # Or you can call the handlers one by one --- - hosts: webservers remote_user: root - name: template configuration file template: src: template.j2 dest: /etc/foo.conf notify: - restart memcached - restart apache # Or you can call the handlers in one call tasks: - name: restart everything command: echo "this task will restart the web services" notify: "restart web services"
Interactive authentication required
Unable to restart service postfix: Failed to restart postfix.service: Interactive authentication required. See system logs and 'systemctl status postfix.service' for details.
Handler are run with the connected user privilege if you want to perform action that requires root privilege, you should become root.
- name: restart postfix service: name=postfix state=restarted become: true