Get list of ip adresses in playbook

Question

I'm new to Ansible and couldn't figure out how to achieve this from the documentation: I have an inventory file like this:

example_site:
  children:
    ...
    example_hosts:
      hosts:
        h1:
          ansible_host: "192.168.0.1"
        h2:
          ansible_host: "192.168.0.2"

Now I want to start a Gluster cluster there in a playbook:

  tasks:
    - name: Create a trusted storage pool
      become: yes
      gluster.gluster.gluster_peer:
        state: present
        nodes:
          - "192.168.0.1"
          - "192.168.0.2"

Is there a way to not hardcode this list of ip addresses? I tried node: groups['example_hosts'], but that did not work.

How can I get a list of ip addresses from the inventory?

Answer 1

The IP addresses of hosts defined in your inventory can be accessed with the ansible_host variable, i.e. hostvars['h1']['ansible_host'] => "192.168.0.1". Since you need the IP address of the hosts in that group as an array, we can iterate over the hosts in group['example_hosts'], which is a list ["h1", "h2"] as well.

In the below example, we create another variable with the list of IP address of hosts in example_hosts group:

    - set_fact:
        cluster_hosts: "{{ cluster_hosts|default([]) + [ hostvars[item]['ansible_host'] ] }}"
      loop: "{{ groups['example_hosts'] }}"
      run_once: true
    - debug:
        var: cluster_hosts

This gives the list of IP addresses in cluster_hosts:

    "cluster_hosts": [
        "192.168.0.1",
        "192.168.0.2"
    ]

This variable can be passed to the nodes parameter of the gluster_peer module:

        nodes: "{{ cluster_hosts }}"