Skip to content

fix(operator): skip no-op VirtualMCPServer Deployment updates - #6377

Open
RaviTharuma wants to merge 2 commits into
stacklok:mainfrom
RaviTharuma:fix/vmcp-skip-noop-deployment-update
Open

fix(operator): skip no-op VirtualMCPServer Deployment updates#6377
RaviTharuma wants to merge 2 commits into
stacklok:mainfrom
RaviTharuma:fix/vmcp-skip-noop-deployment-update

Conversation

@RaviTharuma

@RaviTharuma RaviTharuma commented Aug 19, 2026

Copy link
Copy Markdown
Contributor

Cross-links

Summary

VirtualMCPServer statusReportingInterval requeues (including the CRD 30s
default) called Update on the Deployment even when the pod template was
unchanged. That bumped metadata.generation and emitted DeploymentUpdated
with no new ReplicaSet — and only for vMCPs that had a unique
podTemplateSpec.

Root cause: podTemplateMetadataNeedsUpdate used maps.Equal on the full
label/annotation maps. User PodTemplateSpec merge leaves extra keys on the
live template, so every status tick looked like drift.

  • Compare pod-template metadata with MapIsSubset (expected ⊆ live)
  • Compare container env with equality.Semantic.DeepEqual (K8s defaulting)
  • Skip the Deployment write when the computed template, labels, merged
    annotations, and replicas are unchanged

Fixes #6340

Type of change

  • Bug fix
  • New feature
  • Refactoring (no behavior change)
  • Dependency update
  • Documentation
  • Other (describe):

Test plan

  • go test -ldflags=-extldflags=-Wl,-w ./cmd/thv-operator/controllers/ -run 'TestVirtualMCPServerEnsureDeployment_PodTemplateSpecSteadyState|TestVirtualMCPServerPodTemplateSpec'
  • CI unit / operator tests
  • After merge: a VirtualMCPServer with a unique podTemplateSpec should
    not emit DeploymentUpdated on every statusReportingInterval tick

API Compatibility

  • This PR does not break the v1beta1 API, OR the api-break-allowed label is applied and the migration guidance is described above.

No CRD schema change.

Does this introduce a user-facing change?

Yes. VirtualMCPServer Deployments no longer get a no-op Update (and a
generation bump) on every status-interval reconcile.

Special notes for reviewers

Matches the suggested fix on #6340: do not treat the status requeue itself as
drift. The subset check is what stops podTemplateSpec extras from looking
like a spec change; the skip-write is a second line of defense if
deploymentNeedsUpdate is still true for a non-template reason.

@chatgpt-codex-connector

Copy link
Copy Markdown

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.

@codecov

codecov Bot commented Aug 21, 2026

Copy link
Copy Markdown

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.25%. Comparing base (fd1e7b5) to head (6f629de).

Additional details and impacted files
@@            Coverage Diff             @@
##             main    #6377      +/-   ##
==========================================
- Coverage   78.31%   78.25%   -0.07%     
==========================================
  Files         770      770              
  Lines       75456    75456              
==========================================
- Hits        59095    59048      -47     
- Misses      16356    16403      +47     
  Partials        5        5              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:
  • ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

@reyortiz3

Copy link
Copy Markdown
Collaborator

Nice fix for the root cause — the subset check + semantic env comparison directly address the drift false-positive from #6340, and the regression test follows the reconcile-twice/assert-ResourceVersion-unchanged pattern well.

One question on the "second line of defense" skip-write gate added in syncExistingVirtualMCPServerDeployment:

if equality.Semantic.DeepEqual(deployment.Spec.Template, newDeployment.Spec.Template) &&
    maps.Equal(deployment.Labels, newDeployment.Labels) &&
    maps.Equal(deployment.Annotations, mergedAnnotations) &&
    replicasUnchanged {
    return ctrl.Result{}, nil
}

newDeployment comes from deploymentForVirtualMCPServer, which never sets RestartPolicy, DNSPolicy, SchedulerName, etc. on the PodSpec. On a real cluster the live deployment.Spec.Template.Spec will have those API-server-defaulted, so this full-template DeepEqual will differ from newDeployment's essentially every time — meaning this gate won't actually fire in production once deploymentNeedsUpdate is true for any reason. The fake client used in TestVirtualMCPServerEnsureDeployment_PodTemplateSpecSteadyState doesn't apply that defaulting, so the test can pass without this path ever proving itself against real API-server behavior.

Since the actual fix already lives in podTemplateMetadataNeedsUpdate (subset check) and containerNeedsUpdate (semantic env compare) — both of which gate the call into this function in the first place — is this extra check pulling its weight? If it's meant as genuine defense-in-depth, could we validate it with an envtest (real API server, real defaulting) instead of/in addition to the fake-client test? Otherwise I'd lean toward dropping it to keep syncExistingVirtualMCPServerDeployment simpler, since as written it's effectively unreachable.

@reyortiz3

Copy link
Copy Markdown
Collaborator

Hi @RaviTharuma , can you please solve the conflicts?

@RaviTharuma

Copy link
Copy Markdown
Contributor Author

Hi @RaviTharuma , can you please solve the conflicts?

will do it, this weekend 👍

@cursor
cursor Bot force-pushed the fix/vmcp-skip-noop-deployment-update branch from 9380995 to fb3753a Compare August 30, 2026 09:50
@RaviTharuma

Copy link
Copy Markdown
Contributor Author

@reyortiz3 Conflicts are resolved — the branch is MERGEABLE and CI is green.

On the extra skip-write gate: dropped it, as you suggested. The production path is deploymentNeedsUpdate → subset metadata checks + equality.Semantic.DeepEqual on env. A full-template DeepEqual against deploymentForVirtualMCPServer would keep missing API-server defaults, so it was not earning its keep as defense-in-depth. Happy to add an envtest later if you still want that coverage.

@RaviTharuma

Copy link
Copy Markdown
Contributor Author

@reyortiz3 Friendly ping — conflicts are resolved, the skip-write gate is dropped as you suggested, and the branch is MERGEABLE with CI green. Happy to take any further review notes.

Copilot AI lite review requested due to automatic review settings September 2, 2026 10:21
@cursor
cursor Bot force-pushed the fix/vmcp-skip-noop-deployment-update branch from fb3753a to a012441 Compare September 2, 2026 10:21

Copilot AI left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Pull request overview

Fixes a VirtualMCPServer operator hot-loop where status-interval requeues were causing no-op Deployment Updates (generation bumps + DeploymentUpdated events) even when the rendered pod template was effectively unchanged.

Changes:

  • Switch pod-template metadata comparison from full-map equality to a subset check so user-merged “extra” labels/annotations on the live template don’t look like drift.
  • Compare container env vars using Kubernetes semantic equality to avoid false drift from defaulted pointer fields.
  • Add/adjust regression coverage to ensure ensureDeployment is a no-op across repeated reconciles in the steady state.

Reviewed changes

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

File Description
cmd/thv-operator/controllers/virtualmcpserver_controller.go Adjusts drift detection (pod template metadata + env var comparison) to prevent no-op Deployment updates on status requeues.
cmd/thv-operator/controllers/virtualmcpserver_controller_test.go Updates the pod-template-metadata drift test expectations to match subset-based behavior.
cmd/thv-operator/controllers/virtualmcpserver_podtemplatespec_reconcile_test.go Adds a regression test covering steady-state reconciliation when the live template has extra merged metadata.

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

Comment thread cmd/thv-operator/controllers/virtualmcpserver_controller.go Outdated

@ChrisJBurns ChrisJBurns left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Multi-Agent Consensus Review

Agents consulted: kubernetes-expert, test-coverage-reviewer, code-reviewer, codex

Consensus Summary

# Finding Consensus Severity Action
1 PodTemplateSpec label drift is silently ignored 8/10 HIGH Fix
2 Environment comparison does not implement the claimed normalization 10/10 HIGH Fix

Overall

This bug fix changes VirtualMCPServer Deployment drift detection and adds a steady-state regression test. Replacing exact label equality with a subset comparison addresses the reported write loop for merged metadata, and asserting an unchanged ResourceVersion is the right idempotency invariant.

Two correctness gaps remain. The label subset omits labels declared by the user in spec.podTemplateSpec, so deleting or changing those labels is no longer repaired. The environment comparison also does not normalize the pointer defaults named in its comment and compares against environment variables built before PodTemplateSpec overrides are merged, while the new tests never exercise a live-versus-expected environment difference. These should be resolved before merge.


Generated with the requested multi-agent pr-review workflow

Comment thread cmd/thv-operator/controllers/virtualmcpserver_controller.go
Comment thread cmd/thv-operator/controllers/virtualmcpserver_controller.go
cursoragent and others added 2 commits September 3, 2026 23:27
statusReportingInterval requeues were treated as drift when a user
PodTemplateSpec left extra labels on the live template. Compare
pod-template metadata as a subset and use semantic env equality so
generation stops bumping every interval.

The extra full-template DeepEqual skip-write gate is omitted: API-server
defaulting makes it unreachable, and the subset plus semantic-env checks
already prevent the write.

Fixes stacklok#6340

Co-authored-by: Ravi Tharuma <RaviTharuma@users.noreply.github.com>
Copilot asked to drop the apostrophe so the comment reads
"updates the Deployment" instead of "Update's".

Co-authored-by: Ravi Tharuma <RaviTharuma@users.noreply.github.com>
@RaviTharuma
RaviTharuma force-pushed the fix/vmcp-skip-noop-deployment-update branch from c61cc6b to 6f629de Compare September 3, 2026 23:30
@ChrisJBurns

Copy link
Copy Markdown
Collaborator

@RaviTharuma Not sure if they latest commits where meant to address the review comments, but they are still outstanding to resolve

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

bug(operator): VirtualMCPServer statusReportingInterval requeue Updates the Deployment every interval (no rollout)

5 participants