Provide example/documentation for side_effect

[zstyblik]

Issue Type

• Feature request

Molecule and Ansible details

Not applicable

Desired Behavior

Hello,

please, would it be possible to provide more documentation/examples of what side_effect is and how to use it. I know the feature exists, but I haven't really found any documentation on what it is, what good is it for or how to use it.

Thanks

[decentral1se]

From https://molecule.readthedocs.io/en/latest/configuration.html#provisioner:

The side effect playbook executes actions which produce side effects to the instances(s). Intended to test HA failover scenarios or the like. It is not enabled by default. Add the following to the provisioner’s playbooks section to enable.

provisioner:
name: ansible
playbooks:
side_effect: side_effect.yml

Important

This feature should be considered experimental.

[decentral1se]

Probably worth to add a note to https://etherpad.openstack.org/p/ansible-molecule which is a brain dump for how we can improve the documentation right now. This is definitely not easy to find and we should change that.

[zstyblik]

@lwm, I appreciate your reply. I've read documentation. I even tried to dig into provisioner related code.

I'm "begging", for the lack of better word, for some example of "do this, do that, voilà you get banana". What kind of "code" should go inside side_effect.yml? Any real world example? Surely, somebody had to use it at least once.

I mean no offense. If no such thing is possible eg. it's experimental and we don't know yet, then it's not possible. I'm cool with that.

[decentral1se]

I mean no offense. If no such thing is possible eg. it's experimental and we don't know yet, then it's not possible. I'm cool with that.

All good! No problems. I think it's being done by someone but nothing in the tests (well, I did a quick check). I don't have anything further :/ I've added a note to the etherpad and hopefully we can get something for this. If you do any experimentation (or anyone!) please let us know in this issue.

[mechastorm]

Note that side_effects (from what I understood) is meant to change the state of the environment that is outside of the scope of the role. Example: test a failure or HA.

For future reference (and until official docs have this included), I found the usage of side_effects after some experimentation

Include path to the side_effect.yml as documented in https://molecule.readthedocs.io/en/latest/configuration.html#provisioner and mentioned by @lwm

provisioner:
  name: ansible
  playbooks:
    side_effect: side_effect.yml

Then create the file side_effect.yml in your scenario folder (ie. molecule/default/side_effect.yml)

---
- name: Side Effect
  hosts: all
  become: true

  tasks:
    - name: [EXAMPLE] Start the services
      service:
        name: myservice
        state: started

To run it, you can run the command molecule side-effect

The side-effect is already included in the converge step as documented here https://molecule.readthedocs.io/en/latest/configuration.html#scenario

[geoffreyvanwyk]

side_effect is only part of test. https://ansible.readthedocs.io/projects/molecule/configuration/#scenario