GitHub Actions for Go

GitHub Actions includes CI/CD for free for Open Source repositories. This document contains information on making it work well for Go. See them in action:

$ cat .github/workflows/test.yml
on: [push, pull_request]
name: Test
jobs:
  test:
    strategy:
      matrix:
        go-version: [1.16.x, 1.17.x]
        os: [ubuntu-latest, macos-latest, windows-latest]
    runs-on: ${{ matrix.os }}
    steps:
    - name: Install Go
      uses: actions/setup-go@v2
      with:
        go-version: ${{ matrix.go-version }}
    - name: Checkout code
      uses: actions/checkout@v2
    - name: Test
      run: go test ./...

Summary

Each workflow file has a number of jobs, which get run on specified events, and run concurrently with each other. You can have workflow status badges.

Each job runs on a configuration matrix. For example, we can test two major Go versions on three operating systems.

Each job has a number of steps, such as installing Go, or checking out the repository's code.

FAQs

What about module support?

Go 1.16 and later will already use module mode by default. Go 1.12 and later do the same if a go.mod file is present.

How do I set environment variables?

They can be set up via env for an entire workflow, a job, or for each step:

env:
  GOPROXY: "https://proxy.company.com"
jobs:
  [...]

How do I set environment variables at run-time?

You can use environment files to set environment variables or add an element to $PATH. For example:

steps:
- name: Set env vars
  run: |
      echo "CGO_ENABLED=0" >> $GITHUB_ENV
      echo "${HOME}/goroot/bin" >> $GITHUB_PATH

Note that these take effect for future steps in the job.

How do I set up caching between builds?

Use actions/cache. For example, to cache downloaded modules:

- uses: actions/cache@v2
  with:
    path: ~/go/pkg/mod
    key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
    restore-keys: |
      ${{ runner.os }}-go-

You can also include Go's build cache, to improve incremental builds:

- uses: actions/cache@v2
  with:
    # In order:
    # * Module download cache
    # * Build cache (Linux)
    # * Build cache (Mac)
    # * Build cache (Windows)
    path: |
      ~/go/pkg/mod
      ~/.cache/go-build
      ~/Library/Caches/go-build
      %LocalAppData%\go-build
    key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
    restore-keys: |
      ${{ runner.os }}-go-

This is demonstrated via the test-cache job in this very repository.

See this guide for more details.

How do I run a step conditionally?

You can use if conditionals, using their custom expression language:

- name: Run end-to-end tests on Linux
  if: github.event_name == 'push' && matrix.os == 'ubuntu-latest'
  run: go run ./endtoend

How do I set up a custom build matrix?

You can include extra matrix jobs, and you can exclude specific matrix jobs.

How do I run multiline scripts?

- name: Series of commands
  run: |
    go test ./...
    go test -race ./...

Should I use two workflows, or two jobs on one workflow?

The biggest difference is the UI; workflow results are shown separately. Grouping jobs in workflows can also be useful if one wants to customize the workflow triggers, or to set up dependencies via needs.

How do I set up a secret environment variable?

Follow these steps to set up the secret in the repo's settings. After adding a secret like FOO_SECRET, use it on a step as follows:

- name: Command that requires secret
  run: some-command
  env:
    FOO_SECRET: ${{ secrets.FOO_SECRET }}

How do I install private modules?

It's possible to install modules from private GitHub repositories without using your own proxy. You'll need to add a personal access token as a secret environment variable, as well as configure GOPRIVATE.

- name: Configure git for private modules
  env:
    TOKEN: ${{ secrets.PERSONAL_ACCESS_TOKEN }}
  run: git config --global url."https://YOUR_GITHUB_USERNAME:${TOKEN}@github.com".insteadOf "https://github.com"

env:
  GOPRIVATE: "*.company.com"
jobs:
  [...]

How do I install Linux packages?

Use sudo apt, making sure to only run the step on Linux:

- name: Install Linux packages
  if: matrix.os == 'ubuntu-latest'
  run: sudo apt update && sudo apt install -y --no-install-recommends mypackage

How do I set up a GOPATH build?

Declare GOPATH and clone inside of it:

jobs:
  test-gopath:
    env:
      GOPATH: ${{ github.workspace }}
      GO111MODULE: off
    defaults:
      run:
        working-directory: ${{ env.GOPATH }}/src/github.com/${{ github.repository }}
    steps:
    - name: Checkout code
      uses: actions/checkout@v2
      with:
        path: ${{ env.GOPATH }}/src/github.com/${{ github.repository }}

Quick links

• Concepts, rate limits, etc: https://docs.github.com/en/actions/learn-github-actions

• Syntax and fields reference: https://docs.github.com/en/actions/learn-github-actions/workflow-syntax-for-github-actions

• Environment reference: https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners

• To report bugs: https://github.community/c/code-to-cloud/github-actions/41

Caveats

• actions/checkout#135

git config core.autocrlf defaults to true, so be careful about CRLF endings in your plaintext testdata files on Windows. To work around this, set up the following .gitattributes:

* -text

• actions/runner-images#712

os.TempDir on Windows will contain a short name, since %TEMP% also contains it. Note that case sensitivity doesn't matter, and that os.Open should still work; but some programs not treating short names might break.

> echo %USERPROFILE%
C:\Users\runneradmin
> echo %TEMP%
C:\Users\RUNNER~1\AppData\Local\Temp