Go Code Review

Quick Reference

Review Checklist

• All errors are checked (no _ = err)
• Errors wrapped with context (fmt.Errorf("...: %w", err))
• Resources closed with defer immediately after creation
• No goroutine leaks (channels closed, contexts canceled)
• Interfaces defined by consumers, not producers
• Interface names end in -er (Reader, Writer, Handler)
• Exported names have doc comments
• No naked returns in functions > 5 lines
• Context passed as first parameter
• Mutexes protect shared state, not methods

Kubernetes Operator Specific

• Owner references set with controllerutil.SetControllerReference()
• Finalizers added/removed safely (check for DeletionTimestamp)
• Context propagated through reconcile loops
• Client errors handled (distinguish NotFound vs other errors)
• Status updates separate from spec changes
• Resource watching pattern: Owned resources tracked via ResourceVersion, external resources use explicit watchers (see internal/controller/watchers/)
• Reconcile functions are idempotent (safe to call multiple times)
• Resource updates check semantic equality first (apiequality.Semantic.DeepEqual)
• Return ctrl.Result{Requeue: true} for transient issues, errors for permanent failures
• RBAC markers (//+kubebuilder:rbac) present for all resource access in controllers

When to Load References

• Reviewing error return patterns → error-handling.md
• Reviewing goroutines/channels → concurrency.md
• Reviewing type definitions → interfaces.md
• General Go review → common-mistakes.md

Review Questions

1. Are all error returns checked and wrapped?
2. Are goroutines properly managed with context cancellation?
3. Are resources (files, connections) closed with defer?
4. Are interfaces minimal and defined where used?

Valid Patterns (Do NOT Flag)

These patterns are acceptable and should NOT be flagged as issues:

• _ = err with reason comment - Intentionally ignored errors with explanation

``go _ = conn.Close() // Best effort cleanup, already handling primary error ``

• Empty interface interface{} - For truly generic code (pre-generics codebases)
• Naked returns in short functions - Acceptable in functions < 5 lines with named returns
• Channel without close - When consumer stops via context cancellation, not channel close
• Mutex protecting struct fields - Even if accessed only via methods, this is correct encapsulation
• //nolint directives with reason - Acceptable when accompanied by explanation

``go //nolint:errcheck // Error logged but not returned per API contract ``

• Defer in loop - When function scope cleanup is intentional (e.g., processing files in batches)

Context-Sensitive Rules

Only flag these issues when the specific conditions apply: