Add support for rotating docker configs

[andrasmaroy]

SUMMARY

Add support for rolling updates for docker configs. Based on the same functionality for secrets in #293.

Adding two additional parameters for the docker_config module:

• rolling_versions (default: false): whether to use versioning configs for rolling updates.
• versions_to_keep (default: 5): when using rolling updates, how many of the old versions to keep.

When rolling_versions is set to true configs are created with a _vX postfix in their names where X is replaced with an incremental counter. That counter is also added to the configs as a label with the name of ansible_version. This way when a config is changed a new version is created with an incremented version number instead of deleting it first then creating again. This aims to solve the problem where the config is attached to a service, thus deleting it fails.

This is the recommended approach of updating configs based on the official Docker documentation.

The change is not breaking, users of this module shouldn't expect any changes.

ISSUE TYPE

• Feature Pull Request

COMPONENT NAME

docker_config

ADDITIONAL INFORMATION

The problem this PR aims to solve is the following:
When a config is attached to a service docker won't let it get deleted, thus the current version of the module fails execution if one tries to update a config that is attached to a service already. The recommendation from docker for this is to create a new config with the updated data then update the service definition adding the new config in place of the old one. Afterwards the old config can be safely deleted. Having different names for the config is a non-issue since one can define the mountpoint for the config in the container regardless of its name.

The PR addresses #109

[github-actions]

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Thank you for contribution!✨

This PR has been merged and your docs changes will be incorporated when they are next published.

[felixfontein]

I think it looks good. I will merge if nobody complains until, say, next Saturday.

[WojciechowskiPiotr]

shipit

[felixfontein]

@andrasmaroy thanks for your contribution!
@WojciechowskiPiotr thanks for reviewing!