feat: Propagate LabelPrefix through LMT

[rammanoj]

What this PR does / why we need it:

The PR introduces a way to propagate LabelPrefix through LMT. These LabelPrefixes are then added as prefixes to Linode instance labels, adhering to these rules.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

TODOs:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

[codecov]

Codecov Report

Attention: Patch coverage is 84.21053% with 6 lines in your changes missing coverage. Please review.

Project coverage is 62.88%. Comparing base (5a09046) to head (3666e33).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...nal/controller/linodemachine_controller_helpers.go	83.78%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #799      +/-   ##
==========================================
+ Coverage   62.83%   62.88%   +0.05%     
==========================================
  Files          71       71              
  Lines        7178     7213      +35     
==========================================
+ Hits         4510     4536      +26     
- Misses       2401     2407       +6     
- Partials      267      270       +3     

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[tchinmai7]

do you need to sort here?

[Copilot]

Pull Request Overview

This PR introduces the ability to propagate LabelPrefix configuration from LinodeMachineTemplate to LinodeMachine resources, enabling custom prefixes for Linode instance labels. The implementation includes updating the controller logic to sync label prefix changes and applying the prefix to instance labels according to specific rules based on machine ownership.

• Adds LabelPrefix field to LinodeMachine and LinodeMachineTemplate specs with appropriate CRD validation
• Updates LinodeMachineTemplate controller to propagate label prefix changes to associated machines
• Implements label generation logic that handles prefix application based on machine owner references

Reviewed Changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
api/v1alpha2/linodemachine_types.go	Adds LabelPrefix field to LinodeMachineSpec
config/crd/bases/*.yaml	Updates CRDs with new LabelPrefix field definitions
internal/controller/linodemachinetemplate_controller.go	Updates reconciler to handle label prefix propagation
internal/controller/linodemachine_controller_helpers.go	Implements label generation and instance update logic
internal/controller/linodemachine_controller.go	Updates reconciler to use new instance update logic
e2e/linodemachinetemplate-controller/lmt-tags/*.yaml	Adds e2e tests for label prefix functionality
docs/src/reference/out.md	Updates documentation with new field description

[eljohnson92]

Is there a reason slices.Equal won't work in this case?

[tchinmai7]

slices.Equal only works if the order is the same - https://cs.opensource.google/go/go/+/refs/tags/go1.24.5:src/slices/slices.go;l=20
we'd either have to sort both these lists and then do slices.Equal or take this approach

[rammanoj]

machineTags is created from linodeInstance.Tags. linodeInstance.Tags is initially converted to a map. After performing a few operations, it gets converted back to slice. Practically, the order is not changed but theoretically the map is not an orderedMap. So, there is no guarantee for the order.

[eljohnson92]

I think I would prefer we sort the lists rather than write our own equality logic

[rahulait]

It needs to be rebased from main so that existing GHAs which use pull_request can have their workflow files updated. We merged a fix which fixes the random failures as seen in this PR workflows as well.

[rammanoj]

Dropping as CAPI supports this.