add combined kraft mode

[piif]

Description

introduce a variable kraft_combined to allow combined nodes broker+controller

Fixes #1510

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [X] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How Has This Been Tested?

tests in progress

Checklist:

• [X] Any variable/code changes have been validated to be backwards compatible (doesn't break upgrade)
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] If required, I have ensured the changes can be discovered by cp-ansible discovery codebase
• [ ] My code follows the style guidelines of this project
• [X] I have commented my code, particularly in hard-to-understand areas
• [X] I have made corresponding changes to the documentation
• [X] My changes generate no new warnings
• [ ] Any dependent changes have been merged and published in downstream modules

[cla-assistant[bot]]

All committers have signed the CLA.

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1 out of 2 committers have signed the CLA.

:white_check_mark: piif
:x: Christian Lefebvre

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[piif]

pull request modified after testing on combined and separate nodes, with scram users

[mansisinha]

thanks @piif for your contribution. However, since combined mode is not recommended for production, we do not have any plans to introduce it in cp-ansible. We will work on the scram authentication implementation in isolated mode. cc: @prabhamanepalli

[piif]

hi @mansisinha , sorry, but I disagree with this argument. As a maintainer of a kafka cluster, I need to deploy development, preproduction and production clusters from the same playbook, with just different inventories. Thus, I would like to activate combined mode in dev environment and disable it for production, from an inventory variable, with a default value to "disabled"

[mansisinha]

Hi @piif , we discussed your ask with the team. We can not directly merge the PR at the moment since this requires multiple layers of testing to make sure it does not break any current functionality. We will take this up for future release.