Client: Enable to supply labels as inventory-vars

[superstes]

ARA-Labels can currently only be set inside a playbook or as extra-vars.

As Ansible uses the inventory-system to dynamically set variables - it would make sense to allow users to set those labels inside their inventory.
This PR adds exactly that functionality.

[superstes]

It was unclear to me how integration tests should be added.
Might make sense to add test-cases for it.

For now I've (only) tested it manually:

• Add the ara_playbook_labels variable inside host- and/or group-vars
• Execute jobs
• Check ARA Server - the labels were added
• There seem to be an existing handling for duplicated labels

[softwarefactory-project-zuul]

Build failed.
https://ansible.softwarefactory-project.io/zuul/buildset/65ff36645c594d549f9288154b06b605

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✔️ ara-basic-ansible-core-devel SUCCESS in 5m 57s (non-voting)
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[superstes]

The docs-test error/warning seems to be unrelated (?):
WARNING: Calling get_html_theme_path is deprecated. If you are calling it to define html_theme_path, you are safe to remove that code.

[superstes]

Note: We could of course deduplicate the isinstance and split checks.

[softwarefactory-project-zuul]

Build failed.
https://ansible.softwarefactory-project.io/zuul/buildset/dd90cbb1db26406089ee9a87ddb13209

✔️ ara-tox-py3 SUCCESS in 2m 32s
✔️ ara-tox-linters SUCCESS in 2m 10s
❌ ara-tox-docs FAILURE in 2m 01s
✔️ ara-basic-ansible-core-devel SUCCESS in 4m 47s (non-voting)
✔️ ara-basic-ansible-10 SUCCESS in 5m 01s
✔️ ara-basic-ansible-core-2.16 SUCCESS in 4m 58s
✔️ ara-basic-ansible-core-2.17 SUCCESS in 4m 52s
✔️ ara-container-images SUCCESS in 9m 44s

[dmsimard]

Hi, I added a comment relevant to this PR in the issue: #581 (comment)

I'd like that we consider what is the right solution because iterating over every host is expensive.

[dmsimard]

I will leave this PR open for now but I would rather not go with the suggested implementation for now.

When I have more time I would like to benchmark this approach to demonstrate my point.

[superstes]

If performance of the for-loop is the possible stopper:
Might we be able to use a config-option to opt-in to this functionality?

The labels system might be a lot more useful if inventory-vars could be used 🤔

[dmsimard]

If performance of the for-loop is the possible stopper: Might we be able to use a config-option to opt-in to this functionality?

The labels system might be a lot more useful if inventory-vars could be used 🤔

This came back on my radar recently and may be of interest to you: #596