Breaking changes in molecule v4.0.0

[ssbarnea]

That thread aims to discuss which breaking changes will be included or not inside v4 release.

This new versions is marked as major because we have some API breaking changes affecting the plugin testing. We do not expect to break existing plugins but if those doing imports during testing from molecule.test may need few minor modifications.

In general v4 is seen as a clean-up or refactoring release, not expected to require users to change their existing scenarios in order to make use of the new version.

Already included:

• test api changes, removed use of pytest-helpers-namespace

Proposed:

• Replace ansible-lint dependency with ansible-compat #3190
• removal of molecule features that modify role and library include paths

Feel free to propose new changes to be included or postponed.

[ssbarnea]

Another behavior change proposed for v4 is dropping the automatic installation of requirements.yml files found inside scenarios. Instead molecule will only install requirements.yml found at project_dir (usually git root).

This means that all scenarios from within a repository will make use of the same set of requirements. If current project happens to be a collection this matches its on runtime requirements.

Please us up/down to vote this proposal and if you have reasons to oppose it, please comment below and explain which exact use-case would be broken. Keep in mind that you can still manually install these requirements using dependency step, is only the implicit behavior being removed.

Related:

• Remove offline option ansible-compat#37

[greg-hellings]

My knee jerk reaction was against this, as I thought I used it somewhat frequently. A quick review of my collections confirms that I use it exactly 0 times.

[greg-hellings]

Can you give more details on "removal of molecule features that modify role and library include paths"? Which features will be affected and how?

[ssbarnea]

That indeed a very good question, I think that the code that would be removed would be that one https://github.com/ansible-community/molecule/blob/main/src/molecule/provisioner/ansible.py#L526-L550

Basically I would like to remove molecule special code for adulterating ansible paths, mainly because I want to rely on our shared library to perform such changes.

Keep in mind that users that used ansible environment variable or ansible config files to alter these paths are not affected as ansible will continue to load them.

There are few other areas like https://github.com/ansible-community/molecule/blob/main/src/molecule/provisioner/ansible.py#L428-L436 but I do not expect big changes here because a very similar logic is already included in the ansible-compat library, so the switch should be transparent for the user.

Due to the nature of these changes I do expect to have multiple pre-releases before making a new release as we want to avoid disrupting molecule users and make the upgrade as easy as possible.