"Delegating" handlers to other hosts

Archives Ansible Project
1

Hi all,

Is there any way to delegate handler execution on another host ?

Scenario : some client pushes part of a configuration (e.g. backup
client) to a server and triggers configuration rebuild (assemble) on the
server.

Of course the client in this scenario could issue assemble+delegate_to
but I would rather keep the whole logic contained in the right playbook,
and rebuild only when it is required to.

Thanks,

M

2

Excerpts from Michel Blanc's message of 2013-10-17 09:02:28 -0400:

Is there any way to delegate handler execution on another host ?

I think using 'delegate_to' on the handler itself will do what you
expect, but test it before you take my word for it.

3

Nice idea, I'll try it out.
Thanks Morgan.

M

4

Did that work for you, Michel? I have a similar situation, but I need to copy files to and delegate handlers to a group of servers. I have something like this:

  • name: Deploy
    hosts: source_box

tasks:

  • name: copy files
    command: rsync -az … {{ item }}:/dir
    with_items: groups[‘destination_boxes’]
    notify: service restart

handlers:

  • name: service restart
    service: name=service state=restarted
    delegate_to: SERVER

If SERVER is, say, a literal IP address, it all works. But if I have more than one destination server, I need to make SERVER a variable, and that doesn’t work. Any ideas? Am I missing something?

Nathan

5

this should work:

delegate_to: “{{item}}”"with_items: groups[‘loadbalancers’]
or any list of servers

6

Thanks Brian, that should work well enough. What about the case where the rsync only changes files on a subset of the destination servers though? Is there a way to make sure that only the changed servers get restarted?

Nathan

7

Probably! :slight_smile:

When you are delegating you could still but a “when” condition on it.

If you need to compare facts on other hosts you can use the “hostvars[hostname][‘foo_variable’]” method to get at them.