This is a text-only version of the following page on https://raymii.org:
---
Title       : 	Ansible - Only if host is also in other hostgroup
Author      : 	Remy van Elst
Date        : 	25-11-2014
URL         : 	https://raymii.org/s/tutorials/Ansible_-_Only_if_host_is_also_in_other_hostgroup.html
Format      : 	Markdown/HTML
---



This trick helps you execute actions only when a host is in another hostgroup in
Ansible. For example, you might deploy munin-node via ansible, but you only want
your apache and NGINX plugins deployed on your webservers, not on your database
servers. I found this hard to find in the Ansible documentation, only in the
mailing list was more information.

This example playbook is rolled out to all the hosts (`hosts: all`), because all
the hosts are monitored via Munin. In my ansible-hosts file I also have two
groups, `webservers` and `databaseservers`. I only want my `http-status` plugin
on the webservers, and the `postgres-status` plugin only on the datase servers.
This is how you do that.

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Sample from the playbook:

    
    
          - name: Deploy munin http status code plugin
            copy: 
              src: files/http-status 
              dest: /usr/share/munin/plugins/http-status.sh 
              owner: root 
              group: root 
              mode: 0755
    
          - name: Deploy postgres status plugin
            copy: 
              src: files/postgres-status 
              dest: /usr/share/munin/plugins/posgres-status.py 
              owner: root 
              group: root 
              mode: 0755
    
          - name: Link munin apache plugin
            command: ln -sf /usr/share/munin/plugins/http-status /etc/munin/plugins/http-status
            when: "'webservers' in {{ group_names }}" 
    
          - name: Link munin postgres plugin
            command: ln -sf /usr/share/munin/plugins/postgres-status.py /etc/munin/plugins/postgres-status
            when: "'databaseservers' in {{ group_names }}"    
    

In newer versions of Ansible you would replace the symlink command with the
`file` module, that creates a symlink as well.

By using the `when: "'GROUP_NAME' in {{ group_names }}"` statement in an action
you get more control over the nodes specific actions are run on.

   [1]: https://www.digitalocean.com/?refcode=7435ae6b8212

---

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