Can I use Jinja2 `map` filter in an Ansible play to get values from an array of objects? : <p>I have a playbook for creating some EC2 instances and then doing some stuff with them. The relevant pieces are approximately like:</p>

<pre><code>- name: create ec2 instances
  ec2:
    id: '{{ item.name }}'
    instance_type: '{{ item.type }}'
  register: ec2
  with_items: '{{ my_instance_defs }}'
- name: wait for SSH
  wait_for:
    host: '{{ item.instances[0].private_ip }}'
    port: 22
  with_items: '{{ ec2.results }}'
</code></pre>

<p>This works as intended, but I am not especially happy with the <code>item.instances[0].private_ip</code> expression, partly because it shows really large objects in the play summary. I would love to have the <code>with_items</code> part just be an array of IP addresses, rather than an array of objects with arrays of objects inside them. In Python, I would just do something like:</p>

<pre><code>ips = [r['instances'][0]['private_ip'] for r in ec2['results']]
</code></pre>

<p>And then I would use <code>with_items: '{{ ips }}'</code> in the second task.</p>

<p>Is there a way I can do the same thing using a J2 filter in the YAML of the play? Seems like <a href="http://docs.ansible.com/ansible/playbooks_filters.html#extracting-values-from-containers" rel="noreferrer">http://docs.ansible.com/ansible/playbooks_filters.html#extracting-values-from-containers</a> might be helpful, but I think that presupposes I have an array of keys/indices/whatever.</p>
