Go CI

Go CI

A Go pipeline has exactly four gates: build, vet/lint, test with race detector, vulnerability scan. Everything else is optimization.

1. Baseline GitHub Actions Workflow

name: ci
on:
  push:
    branches: [main]
  pull_request:

permissions:
  contents: read

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-go@v5
        with:
          go-version-file: go.mod   # single source of truth
          cache: true               # caches module + build cache
      - run: go build ./...
      - run: go vet ./...
      - run: go test -race -shuffle=on -coverprofile=coverage.out ./...

  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-go@v5
        with:
          go-version-file: go.mod
      - uses: golangci/golangci-lint-action@v6
        with:
          version: latest

  vuln:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-go@v5
        with:
          go-version-file: go.mod
      - run: go run golang.org/x/vuln/cmd/govulncheck@latest ./...

Key decisions baked in:

• go-version-file: go.mod — never hardcode the Go version in two places.
• cache: true on setup-go handles module and build caches; do not add manual actions/cache steps for Go on top of it.
• -race -shuffle=on — races and order-dependent tests fail in CI, not production.
• permissions: contents: read — least privilege by default.
• Lint in a separate job — it fails fast and parallelizes with tests.

2. golangci-lint Configuration

Commit a .golangci.yml; an unconfigured linter is noise:

linters:
  enable:
    - errcheck      # unchecked errors
    - govet
    - staticcheck
    - errorlint     # %w misuse, == on errors
    - gosec         # security patterns
    - revive        # style, replaces golint
    - misspell
issues:
  exclude-rules:
    - path: _test\.go
      linters: [gosec]  # test code may use weak randomness etc.

Start from this small set and add linters deliberately. Enabling everything produces hundreds of findings nobody triages. nolint directives require a reason: //nolint:gosec // G404: jitter, not crypto.

3. Build Matrix — Only When You Ship It

strategy:
  matrix:
    go: ['1.23', '1.24']         # only versions you support
    os: [ubuntu-latest, macos-latest, windows-latest]

Libraries: test the two newest Go versions (the Go team supports two). Services deployed on Linux: skip the OS matrix — it doubles cost for platforms you never ship. Cross-compilation is cheaper than emulation: GOOS=windows go build ./... catches most portability breaks.

4. Coverage Gate

- run: go test -race -coverprofile=coverage.out ./...
- name: enforce coverage floor
  run: |
    total=$(go tool cover -func=coverage.out | awk '/^total:/ {sub(/%/,"",$3); print $3}')
    echo "coverage: ${total}%"
    awk -v t="$total" 'BEGIN { exit (t < 70.0) }'

Gate on a floor that ratchets up, not a target that gets gamed. Exclude generated code via //go:generated files' build tags or grep filters, not by lowering the floor.

5. Makefile — Local Mirror of CI

CI must run what developers run. One definition, two callers:

.PHONY: build lint test vuln ci

build:
	go build ./...

lint:
	golangci-lint run

test:
	go test -race -shuffle=on -coverprofile=coverage.out ./...

vuln:
	go run golang.org/x/vuln/cmd/govulncheck@latest ./...

ci: build lint test vuln

If CI does anything make ci doesn't, developers discover failures only after pushing. Keep them identical.

6. Speed Rules

• Split lint / test / vuln into parallel jobs (as in §1).
• go test ./... already parallelizes across packages; don't shard a small repo.
• Integration tests behind a build tag run in a separate job or on a schedule, not on every push: go test -tags=integration ./....
• If the build cache misses constantly, check that go.sum is the cache key input (setup-go does this) and that jobs don't mutate it.

Verification Checklist

1. Pipeline has all four gates: build, vet+lint, test -race, govulncheck
2. Go version sourced from go.mod (go-version-file), not duplicated
3. permissions: contents: read set at workflow level
4. Tests run with -race -shuffle=on
5. .golangci.yml committed with a curated linter set
6. Every nolint carries a linter name and a reason
7. Matrix limited to versions/platforms actually supported
8. Coverage floor enforced, generated code excluded
9. make ci reproduces the pipeline locally, byte-for-byte
10. Integration tests isolated behind tags, not slowing every push