Feat/add alphabetical order check

[roguepikachu]

This PR implements a new optional check called sorted-keys that validates whether YAML keys in Kubernetes manifests are sorted in alphabetical order, helping improve consistency and readability.

Fixes #451

How It Works

The check uses gopkg.in/yaml.v3 to parse raw YAML bytes and preserve the original key ordering. It recursively traverses the YAML tree, extracts keys from each mapping node, compares them with their alphabetically sorted version, and reports violations with the exact path location.

• Recursive checking at all nesting levels (configurable)
• Handles arrays of objects (containers, volumes, tolerations, etc.)
• Uses standard lexicographic sorting
• Reports precise paths (e.g., spec.template.spec.containers[0])

Why Raw YAML? Go structs don't preserve field order. The check requires access to original YAML bytes via object.Metadata.Raw to accurately detect key ordering.

Usage

Since this check is disabled by default, users must explicitly enable it:

# Enable sorted-keys along with default checks
kube-linter lint my-manifests/ --include sorted-keys

# Run only sorted-keys check
kube-linter lint my-manifests/ --do-not-auto-add-defaults --include sorted-keys

Or via configuration file:

checks:
  include:
    - sorted-keys

Note

This check is disabled by default, users must explicitly enable it

[codecov]

Codecov Report

❌ Patch coverage is 63.19444% with 53 lines in your changes missing coverage. Please review.
✅ Project coverage is 26.50%. Comparing base (dbd7529) to head (a5264de).
⚠️ Report is 187 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/templates/sortedkeys/template.go	81.25%	19 Missing and 2 partials ⚠️
...templates/sortedkeys/internal/params/gen-params.go	0.00%	19 Missing ⚠️
pkg/lintcontext/mocks/context.go	0.00%	13 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1042       +/-   ##
===========================================
- Coverage   62.36%   26.50%   -35.86%     
===========================================
  Files         197      233       +36     
  Lines        4854     7326     +2472     
===========================================
- Hits         3027     1942     -1085     
- Misses       1439     5230     +3791     
+ Partials      388      154      -234     

Flag	Coverage Δ
unit	26.50% <63.19%> (-35.86%)	⬇️

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[roguepikachu]

Hi @rhybrillou, @rukletsov , can I get a review on this Thanks! I stumbled across this while looking for hacktoberfest. If this PR is okay please add the label hacktoberfest-accepted post merge.

[roguepikachu]

Hi @janisz, could you please take a look at this PR when you get a chance? It seems things have been a bit quiet on the Slack channels lately.

[janisz]

I'll take a deeper look tomorrow. So far I wonder if there's a yaml linter that we could embed and maybe get this for free and some additional features like trailing spaces, tabs/spaces etc. I only know https://github.com/adrienverge/yamllint

Another thing that we need to test is how anchors, aliases, and overrides are handled.

I agree slack is silent and I do not look at it. I was thinking about migration to GitHub issues or discussions to keep everything in a single place or maybe a channel on k8s slack/discord https://www.kubernetes.dev/blog/2025/06/16/changes-to-kubernetes-slack-2025/

[roguepikachu]

@janisz the test changes are implemented could you take a look. Thanks!

[janisz]

LGTM

@roguepikachu Thank you 🎉