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Lint Workflow

Check code quality, formatting, and common mistakes with Go linting tools.

When to Use

  • “lint go code”
  • “format go files”
  • “check code quality”
  • “run gofmt”
  • “run golangci-lint”

Quick Commands

Formatting

# Format all Go files
gofmt -w .

# Check formatting (don't write)
gofmt -d .

# List files needing formatting
gofmt -l .

# Format and organize imports
goimports -w .

Go Vet

# Vet current package
go vet

# Vet all packages
go vet ./...

# Vet specific package
go vet ./internal/handlers

golangci-lint

# Install
go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest

# Run all linters
golangci-lint run

# Auto-fix issues
golangci-lint run --fix

# Run specific linters
golangci-lint run --enable=gosec,exhaustive

# Fast mode (skip cached)
golangci-lint run --fast

Common Linters

Static Analysis

  • staticcheck: Comprehensive static analysis
  • gosec: Security issues
  • errcheck: Unchecked errors
  • govet: Official Go vet
  • ineffassign: Ineffectual assignments

Code Quality

  • gocyclo: Cyclomatic complexity
  • gocognit: Cognitive complexity
  • dupl: Code duplication
  • goconst: Repeated string constants
  • unconvert: Unnecessary type conversions

Style

  • gofmt: Code formatting
  • goimports: Import organization
  • revive: Flexible linter (golint replacement)
  • stylecheck: Style recommendations

Configuration

.golangci.yml Example

run:
  timeout: 5m
  tests: true

linters:
  enable:
    - gofmt
    - goimports
    - govet
    - staticcheck
    - errcheck
    - gosec
    - ineffassign
    - unconvert
    - goconst
    - revive

linters-settings:
  goimports:
    local-prefixes: github.com/yourorg/yourrepo

  govet:
    check-shadowing: true

  revive:
    rules:
      - name: exported
        disabled: true

issues:
  exclude-use-default: false
  max-issues-per-linter: 0
  max-same-issues: 0

Common Fixes

Unused Variables

// Bad
func example() {
    x := 5
    // x never used
}

// Good
func example() {
    _ = 5  // Explicitly unused
}

Error Checking

// Bad
file, _ := os.Open("file.txt")

// Good
file, err := os.Open("file.txt")
if err != nil {
    return err
}
defer file.Close()

Import Organization

// Bad
import (
    "github.com/external/pkg"
    "fmt"
    "myproject/internal"
)

// Good (goimports fixes this)
import (
    "fmt"

    "github.com/external/pkg"

    "myproject/internal"
)

Makefile Example

.PHONY: fmt
fmt:
	gofmt -w .
	goimports -w .

.PHONY: lint
lint:
	golangci-lint run

.PHONY: lint-fix
lint-fix:
	golangci-lint run --fix

.PHONY: vet
vet:
	go vet ./...

.PHONY: check
check: fmt vet lint
	@echo "All checks passed!"

CI/CD Integration

GitHub Actions

- name: Format check
  run: |
    if [ "$(gofmt -l . | wc -l)" -gt 0 ]; then
      echo "Files need formatting:"
      gofmt -l .
      exit 1
    fi

- name: golangci-lint
  uses: golangci/golangci-lint-action@v3
  with:
    version: latest

Best Practices

  1. Run before committing: Add to pre-commit hooks
  2. Use goimports over gofmt: Manages imports too
  3. Enable gosec: Catch security issues
  4. Fix formatting first: Then tackle other issues
  5. Configure for your team: Use .golangci.yml
  6. Run in CI: Ensure consistency
  7. Auto-fix when safe: Use --fix flag

Resources