backend: Stop parseKubeConfig after bad JSON

[harrshita123]

Summary

This PR fixes a backend bug where /parseKubeConfig continued processing after receiving an invalid JSON request body.

The handler already returned a 400 Bad Request, but it did not stop execution afterward. As a result, it could continue with an empty request payload and try to write a second response. This change adds the missing early return and covers the behavior with a regression test.

Related Issue

Fixes #5598

Changes

• Added an early return after invalid JSON is handled in parseKubeConfig.
• Added a regression test to confirm malformed JSON returns only the expected 400 Bad Request response.

Steps to Test

1. Run the focused backend test:

   cd backend && go test ./cmd -run 'TestParseKubeConfigInvalidJSON|TestStatelessClustersKubeConfig'

2. Run backend lint:

   npm run backend:lint

3. Run the full backend test suite:

   npm run backend:test

Screenshots (if applicable)

Not applicable. This is a backend request-handling fix.

Notes for the Reviewer

The production change is intentionally small: one missing return after the bad request response. Valid kubeconfig parsing behavior is unchanged.

[Copilot]

Pull request overview

This PR fixes a bug in the backend /parseKubeConfig handler where it would continue executing after failing to decode an invalid JSON request body, potentially attempting to write a second response. It adds the missing early return and introduces a regression test to ensure the handler responds with only the expected 400 Bad Request.

Changes:

• Add an early return after http.Error(...) on JSON decode failure in parseKubeConfig.
• Add a regression test asserting malformed JSON yields a single 400 response with the expected error body.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
backend/cmd/stateless.go	Stops handler execution immediately after invalid JSON is detected to avoid double-writing responses.
backend/cmd/stateless_test.go	Adds a regression test ensuring malformed JSON returns only the expected 400 error response.

[skoeva]

hi! would you be able to squash your merge commits? this should be helpful to look through

also, could you take a look at the failing backend test?

[harrshita123]

@skoeva
Thanks. I fixed the backend CI timeout and synced the plugin dependencies so the failing check passes again. I’ll squash the commits before merging.

[illume]

Thanks for this PR.

the PR has a merge-main commit; please rebase against main to keep the history clean.

Why this matters

Merge commits from main make the PR history harder to review. Please rebase your branch on top of the latest main instead, then update the PR with the rebased commits.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 6 changed files in this pull request and generated 4 comments.

Files not reviewed (2)

• plugins/headlamp-plugin/package-lock.json: Language not supported
• plugins/headlamp-plugin/template/package-lock.json: Language not supported

[harrshita123]

Contributor

Thanks for this PR.

the PR has a merge-main commit; please rebase against main to keep the history clean.

Why this matters

@illume
Thanks for the review. I rebased the branch on top of main and removed the unrelated workflow and plugin dependency changes. The PR now only contains the backend fix for parseKubeConfig and the regression test. I also verified the backend test suite passes locally.

[illume]

Thanks for working on this.

would you mind rebasing this branch on top of the latest main rather than merging it in?

Why this matters

Merge commits from main make the PR history harder to review. Please rebase your branch on top of the latest main instead, then update the PR with the rebased commits.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

[illume]

Thanks for these changes.

can you please rebase against main to remove the merge main commit?

Why this matters

Merge commits from main make the PR history harder to review. Please rebase your branch on top of the latest main instead, then update the PR with the rebased commits.

[illume]

Thanks for working on this.

would you mind rebasing this branch on top of the latest main rather than merging it in?

Why this matters

Merge commits from main make the PR history harder to review. Please rebase your branch on top of the latest main instead, then update the PR with the rebased commits.

[illume]

Thanks for the contribution.

it looks like there's a merge-main commit in this PR — could you rebase onto main instead?

Why this matters

Merge commits from main make the PR history harder to review. Please rebase your branch on top of the latest main instead, then update the PR with the rebased commits.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

[illume]

Thanks for the contribution.

it looks like there's a merge-main commit in this PR — could you rebase onto main instead?

Why this matters

Merge commits from main make the PR history harder to review. Please rebase your branch on top of the latest main instead, then update the PR with the rebased commits.

The backend test job in CI is failing. Run cd backend && go test ./... to reproduce the errors locally.

How to run the backend tests

Run cd backend && go test ./... to see all failures. Fix the failing tests and commit the result.

[Copilot]

Pull request overview

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

[illume]

Thanks for these changes.

can you please rebase against main to remove the merge main commit?

Why this matters

Merge commits from main make the PR history harder to review. Please rebase your branch on top of the latest main instead, then update the PR with the rebased commits.

Can you please address the open review comments? Once you've resolved each one, please mark it as resolved.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: harrshita123
Once this PR has been reviewed and has the lgtm label, please assign sniok for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[harrshita123]

Thanks for these changes.

can you please rebase against main to remove the merge main commit?

Why this matters
Merge commits from main make the PR history harder to review. Please rebase your branch on top of the latest main instead, then update the PR with the rebased commits.

Can you please address the open review comments? Once you've resolved each one, please mark it as resolved.

@illume
Thanks for the review. I rebased the branch onto the latest upstream main and I resolved all copilot comments .