Code Style

Code Style for openstack-k8s-operators Operators

This skill applies and enforces Go code style best practices for openstack-k8s-operators operators, following openstack-k8s-operators conventions and gopls modernize recommendations.

Code Style Guidelines

1. Modern Go Syntax

Based on gopls modernize and lib-common patterns:

Slice Declaration

// Bad: Old style
var items []string = []string{}

// Good: Modern style
var items []string

Map Declaration

// Bad: Old style
var configs map[string]interface{} = make(map[string]interface{})

// Good: Modern style
var configs = make(map[string]interface{})

String Building

// Bad: Inefficient concatenation
result := ""
for _, item := range items {
    result += item + "\n"
}

// Good: Use strings.Builder
var builder strings.Builder
for _, item := range items {
    builder.WriteString(item)
    builder.WriteString("\n")
}
result := builder.String()

2. Controller-Runtime Patterns

Error Handling

// Good: Proper error wrapping
if err := r.Get(ctx, req.NamespacedName, &instance); err != nil {
    if errors.IsNotFound(err) {
        return ctrl.Result{}, nil
    }
    return ctrl.Result{}, fmt.Errorf("failed to get instance: %w", err)
}

Logging

// Good: Structured logging with context
log := ctrl.LoggerFrom(ctx).WithValues("instance", instance.Name)
log.Info("Starting reconciliation")

Status Updates

// Good: Proper status condition handling
meta.SetStatusCondition(&instance.Status.Conditions, metav1.Condition{
    Type:    "Ready",
    Status:  metav1.ConditionTrue,
    Reason:  "ReconciliationSuccessful",
    Message: "Instance successfully reconciled",
})

3. Error Handling

// Bad: capitalized error string
return fmt.Errorf("Failed to create configmap")

// Good: lowercase, no punctuation, wrapped with context
return fmt.Errorf("failed to create configmap: %w", err)

// Bad: unnecessary else after error return
if err != nil {
    return err
} else {
    doSomething()
}

// Good: normal flow at minimal indentation
if err != nil {
    return err
}
doSomething()

// Bad: discarding errors
result, _ := someFunction()

// Good: always handle errors
result, err := someFunction()
if err != nil {
    return fmt.Errorf("failed to do something: %w", err)
}

4. Naming Conventions

// Bad: non-Go naming
MAX_RETRIES := 3
func GetOwner() string {}
appId := "123"

// Good: MixedCaps, no Get prefix, consistent initialisms
maxRetries := 3
func Owner() string {}
appID := "123"

// Bad: long receiver names
func (reconciler *GlanceReconciler) Reconcile(...) {}
func (this *GlanceReconciler) Reconcile(...) {}

// Good: short, consistent receiver (1-2 letters)
func (r *GlanceReconciler) Reconcile(...) {}

// Bad: meaningless package names
package util
package common
package helpers

// Good: descriptive, lowercase, single-word
package glance
package endpoint
package condition

5. Interface Design

// Bad: large interface defined in the implementation package
type Storage interface {
    Get(key string) ([]byte, error)
    Set(key string, value []byte) error
    Delete(key string) error
    List(prefix string) ([]string, error)
    Watch(prefix string) <-chan Event
}

// Good: small interface defined by the consumer, only methods actually needed
type Reader interface {
    Get(key string) ([]byte, error)
}

// Bad: returning interface
func NewStore() StoreInterface { return &store{} }

// Good: return concrete type, accept interfaces
func NewStore() *Store { return &store{} }

6. Context and Concurrency

// Bad: context as struct field
type Server struct {
    ctx context.Context
}

// Good: context as first parameter
func (s *Server) Process(ctx context.Context, req Request) error {}

// Bad: goroutine with unclear lifetime
go func() {
    for {
        doWork()
    }
}()

// Good: clear goroutine lifecycle with context
go func() {
    for {
        select {
        case <-ctx.Done():
            return
        case item := <-ch:
            process(item)
        }
    }
}()

7. openstack-k8s-operators Operator Conventions

Finalizer Handling

// Good: Consistent finalizer pattern
const FinalizerName = "operator.openstack.org/finalizer"

if instance.DeletionTimestamp != nil {
    return r.handleDeletion(ctx, &instance)
}

if !controllerutil.ContainsFinalizer(&instance, FinalizerName) {
    controllerutil.AddFinalizer(&instance, FinalizerName)
    return ctrl.Result{}, r.Update(ctx, &instance)
}

Resource Management

// Good: Proper owner references
if err := ctrl.SetControllerReference(&instance, resource, r.Scheme); err != nil {
    return fmt.Errorf("failed to set owner reference: %w", err)
}

8. Testing Patterns

Ginkgo Best Practices

// Good: Descriptive test structure
var _ = Describe("Nova Controller", func() {
    Context("When creating a Nova instance", func() {
        BeforeEach(func() {
            // Setup
        })

        It("Should create required resources", func() {
            // Test implementation
        })
    })
})

Mock Usage

// Good: Proper interface mocking
//go:generate mockery --name=ServiceInterface --output=../mocks
type ServiceInterface interface {
    CreateService(ctx context.Context, svc *corev1.Service) error
}

Automated Style Fixes

The skill provides automated fixes for:

1. Modernization

• Convert old slice/map declarations
• Update string concatenation to use strings.Builder
• Fix inefficient loops and patterns
• Apply gopls modernize suggestions

2. Imports

• Organize imports according to Go conventions
• Remove unused imports
• Group standard, third-party, and local imports

3. Variable Naming

• Apply Go naming conventions
• Fix exported vs unexported naming
• Ensure consistent abbreviations

4. Function Signatures

• Add context parameters where missing
• Proper error return patterns
• Consistent receiver naming

Style Enforcement Tools

Built-in Analyzers

# Run style analysis
gopls check <file>

# Apply modernization fixes
gopls fix -a fillstruct,unusedparam <file>

# Check with golangci-lint
golangci-lint run --enable-all

Custom Rules

• openstack-k8s-operators-specific patterns
• Controller-runtime best practices
• OpenStack operator conventions
• lib-common integration patterns

Integration with Development Workflow

Pre-commit Hooks

# .pre-commit-config.yaml
repos:
  - repo: local
    hooks:
      - id: go-style-check
        name: Go Style Check
        entry: ./scripts/style-check.sh
        language: script
        files: '\.go$'

IDE Configuration

// VSCode settings for openstack-k8s-operators operators
{
  "go.lintTool": "golangci-lint",
  "go.lintFlags": ["--config", ".golangci.yml"],
  "gopls": {
    "experimentalPostfixCompletions": true,
    "analyses": {
      "unusedparams": true,
      "shadow": true
    }
  }
}

Usage

Invoke /code-style to:

1. Analyze Current Code: Scan for style issues and improvement opportunities
2. Apply Automated Fixes: Fix common patterns and modernize syntax
3. Generate Style Report: Detailed analysis with specific recommendations
4. Create Action Items: Use TodoWrite to track style improvements

Examples

# Analyze entire project
/code-style analyze-project

# Fix specific file
/code-style fix-file controllers/nova_controller.go

# Check against lib-common patterns
/code-style check-libcommon

# Apply gopls modernize
/code-style modernize

Reference

• Effective Go
• Go Code Review Comments
• Google Go Style Decisions
• lib-common patterns
• gopls modernize
• openstack-k8s-operators conventions
• Controller-runtime best practices