Fix: consider additional config for default user creds

[Zerpet]

This closes #1018

Note to reviewers: remember to look at the commits in this PR and consider if they can be squashed

Summary Of Changes

The RabbitMQ operator now respects default_user and default_pass
values provided in the additionalConfig field of the RabbitmqCluster
manifest when creating the default user secret. Previously, the operator
would generate random credentials, leading to mismatches and confusion.

This change modifies the Build function in
internal/resource/default_user_secret.go to parse the additionalConfig
string. If default_user and default_pass are present, their values
are used. Otherwise, random credentials are generated, maintaining backward
compatibility.

Unit tests in internal/resource/default_user_secret_test.go and
integration tests in controllers/rabbitmqcluster_controller_test.go have
been added to verify this behavior.

Local Testing

Unit and integration tests passing.

$ make unit-tests integration-tests

[Zerpet]

Hold merge until we have produced 2.17.0

[mkuratczyk]

Looks good, thanks. My only worry is the compatibility of the ini format as used by RabbitMQ vs github.com/go-ini/ini/. If I'm not mistaken, with this change, we now require additionalConfig to pass go-ini validation, which was not the case before. I'm sure it it will work in most cases, but I don't know about the compatibility of ini formats with more complex content

[Zerpet]

That's an interesting point I hadn't consider 🤔 It's always possible to fallback to advanced config. Undesirable, but go-ini validation won't block any user completely. Happy to hold if you want to try to break this PR?

[Zerpet]

Bump for reviews! @MirahImage @mkuratczyk

[Copilot]

Pull Request Overview

This PR adds support for reading default RabbitMQ user credentials from the spec.rabbitmq.additionalConfig field instead of always generating them randomly. When default_user and/or default_pass are specified in additionalConfig, those values are used in the default-user Secret. If not specified, credentials are randomly generated as before.

• Adds logic to parse additionalConfig as INI format and extract default_user and default_pass
• Implements fallback behavior to generate credentials when not found in config
• Adds unit tests and integration tests for the new functionality

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
internal/resource/default_user_secret.go	Implements credential extraction from additionalConfig with fallback to random generation, includes import formatting fixes
internal/resource/default_user_secret_test.go	Adds unit test for the new credential extraction behavior, includes import formatting fix
controllers/rabbitmqcluster_controller_test.go	Adds integration test verifying credentials from additionalConfig appear in the Secret

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