How can I get the hosts running a certain role from within that role

Question

I'm trying to setup a Zookeeper cluster and in order to set the url that points to the ZK nodes I would like to know which are the ip addresses of the hosts running the current role.

I know that from the playbook I can pass the hosts machines through a variable but it would be nice to check this within the role.

score 1 · Answer 1 · answered Aug 14 '17 at 12:19

1

If you are interested in the IP the host that is currently executing the role has, just use the builtin ansible fact for that, e.g. :

- debug:
    var={{ "ansible_default_ipv4['address'] }}"

answered Aug 14 '17 at 12:19

ProfHase85

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Well, I'm interested on all the hosts running that role – Painy James Aug 14 '17 at 12:37
This is not the way ansible works. You can imagine a role as a script running on every single host of your playbook (usually in parallel). There is no connection. – ProfHase85 Aug 14 '17 at 13:03

score 1 · Answer 2 · answered Aug 14 '17 at 13:47

I don't think Ansible supplies a variable to access the hosts that a role is being applied to. If you want to get the active hosts in the current play, use ansible_play_hosts (or play_hosts if your ansible version < 2.2).

However, I think a better solution would be to group your zookeeper nodes together in your inventory.

[zookeeper_nodes]
node1
node2
node3

From there you can access variables from those hosts using groups and hostvars

{% for host in groups['zookeeper_nodes'] %}
{{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}
{% endfor %}

See Ansible's docs on magic variables for more info.

How can I get the hosts running a certain role from within that role

2 Answers2