Ansible: get docker container output during container creation - ansible

Question

I'm trying to create a docker container which generates a secretkey using Ansible, but the docker_container doesn't seem to return the container output.
If I ssh into the server and run
root#localhost:~# docker run --rm sentry-onpremise config generate-secret-key
I get the desired output. A secret key such as this
q16w8(5s9_+%4#z8m%c%0uzb&agf0pn+6zfocraponasww&r)f
But if I try to run the same command using an Ansible playbook, the docker container is executed, but no value is returned:
...
- name: Cria secret key para utilizacao em passos seguintes
docker_container:
name: sentry-key-generator
cleanup: True
image: sentry-onpremise
command: config generate-secret-key
register: saida
tags:
- debug
- fail:
msg: "Valor de saida: {{ saida }}"
tags:
- debug
...
fatal: [45.56.93.133]: FAILED! => {
"changed": false,
"failed": true,
"invocation": {
"module_args": {
"msg": "Valor de saida: {u'changed': True, u'ansible_facts': {}}"
},
"module_name": "fail"
},
"msg": "Valor de saida: {u'changed': True, u'ansible_facts': {}}" }
Is this a limitation with the docker_container module? Do I have to setup any other configuration in docker or ansible to get the container output?

Answer 1

This is a bug that was introduced in Ansible 2.2.x, that strips ansible_docker_container away from results.
See:
https://github.com/ansible/ansible/issues/22323
https://github.com/ansible/ansible/issues/20543
Patch:
https://github.com/ansible/ansible/pull/22324/files
The fix is to be released with Ansible 2.3.x