Ansible ssh keys

main.yml

---
- hosts: default
  remote_user: root
  vars:
    users:
    - foo
    - bar
    - baz
    - quux
    keys: {}

  tasks:
  - name: gather SSH keys
    set_fact:
      keys: "{{ {item: lookup('fileglob','keydir/'+item+'@key*.pub', wantlist=True) | sort} | combine(keys) }}"
    with_items: "{{users}}"

  - name: check that SSH keys exist
    assert:
      that: "{{keys[item] | length != 0}}"
      msg: "user '{{item}}' doesn't exist or has no keys"
    with_items: "{{users}}"

  - name: setup SSH keys for root
    template: src=ssh_keys.j2 dest=/root/.ssh/authorized_keys

ssh_keys.j2

{% for user in users: %}
# {{user}}
{% for keyfile in keys[user] %}
{{ lookup('file', keyfile) }}
{% endfor %}

{% endfor %}