How to list all currently targeted hosts in an Ansible play

Question

I am running an Ansible play and would like to list all the hosts targeted by it. Ansible docs mentions that this is possible, but their method doesn't seem to work with a complex targeted group (targeting like hosts: web_servers:&data_center_primary)

I'm sure this is doable, but cant seem to find any further documentation on it. Is there a var with all the currently targeted hosts?

Answer 1

You are looking for 'play_hosts' variable

--- - hosts: all    tasks:     - name: Create a group of all hosts by app_type       group_by: key={{app_type}}      - debug: msg="groups={{groups}}"       run_once: true  - hosts: web:&some_other_group    tasks:    - debug: msg="play_hosts={{play_hosts}}"      run_once: true 

would result in

TASK: [Create a group of all hosts by app_type] ******************************* changed: [web1] => {"changed": true, "groups": {"web": ["web1", "web2"], "load_balancer": ["web3"]}}  TASK: [debug msg="play_hosts={{play_hosts}}"] ********************************* ok: [web1] => {     "msg": "play_hosts=['web1']" } 

inventory:

[proxy] web1 app_type=web web2 app_type=web web3 app_type=load_balancer  [some_other_group] web1 web3 

Answer 2

You can use the option --list-hosts to only list hosts a playbook would affect.

Also, there is the dict hostvars which holds all hosts currently known to Ansible. But I think the setup module had to be run on all hosts, so you can not skip that step via gather_facts: no.