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GitHub Actions

warning

Always specify the action version, eg actions/checkout@v3 instead of actions/checkout, otherwise the pipeline can suddenly break with a new release of the action. Rationale

Docs: https://docs.github.com/en/actions

Reference: https://docs.github.com/en/actions/reference

Copilot instructions - https://github.com/github/awesome-copilot/blob/main/instructions/github-actions-ci-cd-best-practices.instructions.md

TODO Guide to learn: https://resources.github.com/learn/pathways/automation/. Has 3 levels: essentials, intermediate and advanced

Marketplace: https://github.com/marketplace?type=actions

Features: https://github.com/features/actions

Changelog: https://github.blog/changelog/label/githubactions/

https://github.com/topics/github-actions

https://github.com/sdras/awesome-actions

Run your GitHub Actions locally - https://github.com/nektos/act

GitHub hosted runners preinstalled software: https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners#preinstalled-software

Terraform module for scalable GitHub action runners on AWS - https://github.com/philips-labs/terraform-aws-github-runner

Self-hosted GitHub runners on AWS - https://hyperenv.com

Roadmap: https://github.com/orgs/github/projects/4247/views/1?filterQuery=label%3Aactions

Concepts​

A workflow is triggered in response to an event (eg push to main or open a pull request), manually, on schedule or using the REST API.

  • A workflow runs a series of jobs.
  • A job runs a series of steps.
    • Jobs run in parallel by default, but they can depend on (wait for) other jobs.
  • A step either uses an action or runs a command, a series of commands or a shell script.
    • Steps run sequentially.
name: Print CI environment variable
on: [push]
jobs:
  echo_ci:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - run: echo "$CI"

From Understanding GitHub Actions.

Event - on

GitHub Actions goes beyond just DevOps and lets you run workflows when other events happen in your repository. For example, you can run a workflow to automatically add the appropriate labels whenever someone creates a new issue in your repository.

An event is a specific activity in a repository that triggers a workflow run. For example, activity can originate from GitHub when someone creates a pull request, opens an issue, or pushes a commit to a repository. You can also trigger a workflow run on a schedule, by posting to a REST API, or manually.

For a complete list of events that can be used to trigger workflows, see Events that trigger workflows.

Workflow

Your workflow contains one or more jobs which can run in sequential order or in parallel. Each job will run inside its own virtual machine runner, or inside a container, and has one or more steps.

Job - jobs → steps → run/uses

A job is a set of steps in a workflow that execute on the same runner. Each step is either a shell script that will be executed (run), or an action that will be run (uses). Steps are executed in order and are dependent on each other. Since each step is executed on the same runner, you can share data from one step to another. For example, you can have a step that builds your application followed by a step that tests the application that was built.

You can configure a job's dependencies with other jobs; by default, jobs have no dependencies and run in parallel with each other. When a job takes a dependency on another job, it will wait for the dependent job to complete before it can run.

Action - uses

An action is a custom application for the GitHub Actions platform that performs a complex but frequently repeated task. Use an action to help reduce the amount of repetitive code that you write in your workflow files. An action can pull your git repository from GitHub, set up the correct toolchain for your build environment, or set up the authentication to your cloud provider.

You can write your own actions, or you can find actions to use in your workflows in the GitHub Marketplace. For more information, see "Creating actions."

Runner - runs-on

A runner is a server that runs your workflows when they're triggered. Each runner can run a single job at a time. Each workflow run executes in a fresh, newly-provisioned virtual machine.

GitHub provides Ubuntu Linux, Microsoft Windows, and macOS runners to run your workflows. If you need a different operating system or require a specific hardware configuration, you can host your own runners.

Workflow examples​

Official starter workflows: https://github.com/actions/starter-workflows

Examples: https://docs.github.com/en/actions/tutorials

Example workflows that demonstrate the features of GitHub Actions - https://docs.github.com/en/actions/examples - Link does not work now, see https://web.archive.org/web/20240807225554/https://docs.github.com/en/actions/examples

Awesome Actions (curated list): https://github.com/sdras/awesome-actions

Node.js​

ESLint​

Interesting workflows​

Actions​

Marketplace: https://github.com/marketplace?type=actions

Marketplace most starred/installed actions: https://github.com/marketplace?category=&query=sort%3Apopularity-desc&type=actions&verification=

Awesome Actions (curated list): https://github.com/sdras/awesome-actions

Curated list of useful Github actions - https://github.com/GuillaumeFalourd/useful-actions

Commonly used actions​

Useful actions​

  • paths-filter: Conditionally run actions based on files modified by PR, feature branch or pushed commits
  • Secrets Sync Action: Define and rotate secrets in a single repository and have them synced to all other repositories in the Github organization or beyond

AWS actions​

Note that GitHub runners already come with the AWS CLI installed, see https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners#preinstalled-software

AWS S3 actions​

Terraform actions​

https://github.com/marketplace?type=actions&query=terraform+

Learn​

Examples: https://docs.github.com/en/actions/tutorials

Midudev - GitHub Actions TUTORIAL Desde Cero - Integración continua (CI/CD) - https://www.youtube.com/watch?v=sIhm4YOMK6Q&list=PLV8x_i1fqBw0Kn_fBIZTa3wS_VZAqddX7&index=62 - Repository: https://github.com/midudev/pokedex-for-ci/blob/main/.github/workflows/pipeline.yml

How to build a CI/CD pipeline with GitHub Actions in four simple steps: https://github.blog/2022-02-02-build-ci-cd-pipeline-github-actions-four-steps/

7 advanced workflow automation features with GitHub Actions: https://github.blog/2021-11-18-7-advanced-workflow-automation-features-with-github-actions/

GitHub Actions Pitfalls - https://news.ycombinator.com/item?id=32970198

https://kodekloud.com/courses/github-actions

https://kodekloud.com/courses/github-actions-certification

Run​

Run multiple commands with |:

name: Multiline
on: [push]
jobs:
  echo_ci:
    runs-on: ubuntu-latest
    steps:
      - name: 'Print files'
        run: |
          echo "Print files"
          ls -la

Run a script file:

name: Script file
on: [push]
jobs:
  run_script:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4
      - name: Run shell script
        run: ./my-script.sh

The script lives at the root of the git repository. You need to get the code fist.

Contexts​

https://docs.github.com/en/actions/reference/contexts-reference

https://docs.github.com/en/actions/reference/workflows-and-actions/contexts

${{ github.sha }}
${{ github.ref }}
${{ secrets.API_TOKEN }}
${{ vars.USERNAME }}
${{ inputs.app_version }}

Secrets are encrypted, whereas variables are shown as plain text. See https://github.blog/changelog/2023-01-10-github-actions-support-for-configuration-variables-in-workflows/

Environment variables​

https://docs.github.com/en/actions/how-tos/write-workflows/choose-what-workflows-do/use-variables

Environment variables available by default ($GITHUB_ENV, $GITHUB_OUTPUT etc.) - https://docs.github.com/en/actions/reference/workflows-and-actions/variables#default-environment-variables

You can set environment variables scoped to the entire workflow, a job or a step. Often you set environment variables from secrets and variables.

Inside run we can use the runner environment variables using bash shell interpolation ($AWS_REGION), and in most cases also use contexts (${{ env.AWS_REGION }}). The difference is that the context will be interpolated and replaced by a string before the job is sent to a runner. However, at the other parts of the workflow you need to use context, not the runner environment variables.

env:
  ENVIRONMENT: staging

jobs:
  deploy:
    runs-on: ubuntu-latest
    env:
      AWS_REGION: ${{ vars.AWS_REGION }}
      API_TOKEN: ${{ secrets.API_TOKEN }}
    steps:
      - name: Say hello
        env:
          Name: Albert
        # In run we can use both {{ contexts }} and bash $substitution
        run: |
          echo "Hello $Name! The environment is $ENVIRONMENT and the region is $AWS_REGION."
          if [[ ${{ github.ref_name }} == 'main' ]]; then
            echo "Branch is main"
          fi
      - name: Say hello if N. Virginia
        # But here we can only use the {{ contexts }}
        if: ${{ env.AWS_REGION == 'useast' }}
        run: echo "Hi N. Virginia!"

Set environment variables with $GITHUB_ENV​

https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-commands#setting-an-environment-variable

You can use this to pass values to subsequent steps. (You can also use $GITHUB_OUTPUT, see below.) From https://docs.github.com/en/actions/how-tos/write-workflows/choose-what-workflows-do/use-variables#passing-values-between-steps-and-jobs-in-a-workflow

If you generate a value in one step of a job, you can use the value in subsequent steps of the same job by assigning the value to an existing or new environment variable and then writing this to the GITHUB_ENV environment file.

steps:
  - name: Set the value
    id: step_one
    run: |
      echo "action_state=yellow" >> "$GITHUB_ENV"
  - name: Use the value
    id: step_two
    run: |
      printf '%s\n' "$action_state" # This will output 'yellow'

From https://stackoverflow.com/a/66358561/4034572

steps:
  - name: Set the value
    id: step_one
    run: |
      echo "FOO=$(git status)" >> $GITHUB_ENV
  - name: Use the value
    id: step_two
    run: |
      echo "${{ env.FOO }}"

Functions​

https://docs.github.com/en/actions/reference/evaluate-expressions-in-workflows-and-actions#functions

  • contains('xyz', 'y') is true
  • startsWith('xyz', 'y') is false
  • endsWith('xyz', 'y') is false
environment: ${{ contains(inputs.profile, 'dev') && 'dev' || inputs.profile }}

Status check functions​

https://docs.github.com/en/actions/reference/evaluate-expressions-in-workflows-and-actions#status-check-functions

  • success()
  • failure()
  • always()
  • cancelled()

It's important to note that failure():

  • Returns true when any previous step of a job fails. If you have a chain of dependent jobs, failure() returns true if any ancestor job fails.
  • You can include extra conditions for a step to run after a failure, but you must still include failure() to override the default status check of success() that is automatically applied to if conditions that don't contain a status check function.
jobs:
  xyz:
    steps:
      - name: Step 1
        run: npm run step1
      - name: Step 2
        id: step_2
        run: npm run step2
      - name: Send slack notification _only_ if step 2 fails
        uses: slackapi/slack-github-action@v1.23.0
        if: ${{ failure() && steps.step_2.conclusion == 'failure' }}
        with:
          payload: |
            {
              "app": "${{ github.repository }}",
              "environment": "${{ env.ENV }}",
              "version": "RC/Tag/Commit: ${{ env.checkout_ref || github.sha }}",
              "branch": "${{ github.ref_name }}",
              "execution_url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
              "html_report": "https://${{ env.REPORTS_PAGES_SUBDOMAIN }}/${{ env.REPORTS_PAGES_PATH }}/${{ env.FEATURE_BRANCH_NAME }}/"
            }
        env:
          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}

Manually triggered workflow​

You need the on workflow_dispatch event, see https://docs.github.com/en/actions/using-workflows/manually-running-a-workflow

Note that the workflow needs to be merged on a main branch, otherwise you won't see it on the Actions page: This event will only trigger a workflow run if the workflow file is on the default branch. source

Example of a dropdown:

name: Native Apps Build

defaults:
  run:
    working-directory: apps/patient

on:
  workflow_dispatch:
    inputs:
      platform:
        description: 'iOS and/or Android'
        required: true
        type: choice
        default: 'ios'
        options:
          - ios
          - android
          - ios-and-android

jobs:

type can be string, choice, boolean and environment - see https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#onworkflow_dispatchinputs

Run a single workflow or job at a time​

https://docs.github.com/en/actions/using-jobs/using-concurrency

https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#concurrency

Example from https://github.com/actions/starter-workflows/blob/68abeab3718d5d2d5f224103b807c547467e27f3/pages/static.yml#L18-L21 that ensures only one GitHub pages concurrent deployment:

# Allow only one concurrent deployment
concurrency:
  group: 'pages'
  cancel-in-progress: true

Run only if a folder or file has changed​

Use the paths filter:

on:
  push:
    branches: [main]
    paths:
      - src/**
      - package.json

See Patterns to match file paths for how to write the paths.

Docs: https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#onpushpull_requestpull_request_targetpathspaths-ignore

Run job only when a folder changes - https://github.com/orgs/community/discussions/25669

There's also paths-ignore that instead excludes.

Note that "You cannot use both the paths and paths-ignore filters for the same event in a workflow", but you can use ! to negate/exclude and achieve the same.

Change directory​

Use working-directory, eg:

# If you use 'defaults' it applies to all 'run' steps in a workflow
defaults:
  run:
    working-directory: web

Running actions in another directory - https://stackoverflow.com/questions/58139175/running-actions-in-another-directory

Docs (search for working-directory):

Create custom actions and reuse workflows​

Reusing workflows - https://docs.github.com/en/actions/using-workflows/reusing-workflows

About custom actions - https://docs.github.com/en/actions/creating-actions/about-custom-actions

Creating and publishing actions - https://docs.github.com/en/actions/how-tos/creating-and-publishing-actions

GitHub Actions: reusable workflows is generally available - https://github.blog/2021-11-29-github-actions-reusable-workflows-is-generally-available/

You can call a workflow on the same repository with [uses](https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_iduses.

Overview: https://stackoverflow.com/questions/59757355/reuse-portion-of-github-action-across-jobs

https://cardinalby.github.io/blog/post/github-actions/dry-reusing-code-in-github-actions

https://stackoverflow.com/questions/65242830/in-a-github-actions-workflow-is-there-a-way-to-have-multiple-jobs-reuse-the-sam

https://michaelcurrin.github.io/dev-cheatsheets/cheatsheets/ci-cd/github-actions/reusable-workflows.html

Composite actions​

A composite action allows you to combine multiple workflow steps within one action. For example, you can use this feature to bundle together multiple run commands into an action, and then have a workflow that executes the bundled commands as a single step using that action. source

Creating a composite action - https://docs.github.com/en/actions/creating-actions/creating-a-composite-action

GitHub Actions: Reduce duplication with action composition - https://github.blog/changelog/2021-08-25-github-actions-reduce-duplication-with-action-composition/

It can be saved locally on the same repository, see Example: Using an action in the same repository as the workflow. The file name must be action.yml, eg github/actions/lighthouse/action.yml.

This is the local action:

./.github/actions/lighthouse/action.yml
name: 'Lighthouse'
description: 'Run Lighthouse'
inputs:
  some_parameter:
    description: 'The description'
    required: true
runs:
  using: 'composite'
  steps:
    - name: Run Lighthouse
      uses: treosh/lighthouse-ci-action@v10
    - name: Publish results
      uses: actions/github-script@v6
      with:
        script: |
        # ...

And this is how you call it:

./.github/workflows/some-workflow.yml
  lighthouse:
    name: Feature Environment Lighthouse
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v3
      - name: Download build artifact
        uses: actions/download-artifact@v3
        with:
          name: dist
          path: dist
      - name: Lighthouse
        uses: ./.github/actions/lighthouse
        with:
          some_parameter: "some_value"

Setting output parameters with $GITHUB_OUTPUT​

This can be done for steps and for jobs.

Note that there is also GITHUB_STATE.

For steps​

https://michaelcurrin.github.io/dev-cheatsheets/cheatsheets/ci-cd/github-actions/persist.html

https://stackoverflow.com/questions/59191913/how-do-i-get-the-output-of-a-specific-step-in-github-actions

https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-commands#setting-an-output-parameter

      - name: Set color
        id: color-selector
        run: echo "SELECTED_COLOR=green" >> "$GITHUB_OUTPUT"
      - name: Get color
        env:
          SELECTED_COLOR: ${{ steps.color-selector.outputs.SELECTED_COLOR }}
        run: echo "The selected color is $SELECTED_COLOR"

Use printf instead of echo to deal with new lines source:

  lighthouse:
    name: Lighthouse
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      # ...
      - name: Lighthouse
        id: lighthouse
        run: |
          npm install -g @lhci/cli@0.12.x --no-fund
          LHCI=$(lhci autorun --collect.staticDistDir=web-build)
          printf "$LHCI"
          LIGHTHOUSE_REPORT_URL=$(printf "$LHCI" | grep 'Open the report at' | awk '{print $NF}')
          printf "$LIGHTHOUSE_REPORT_URL"
          echo "LIGHTHOUSE_REPORT_URL=$LIGHTHOUSE_REPORT_URL" >> $GITHUB_OUTPUT
        env:
          LHCI_GITHUB_APP_TOKEN: ${{ secrets.LHCI_GITHUB_APP_TOKEN }}
      - name: Comment Lighthouse report URL on pull-request
        uses: actions/github-script@v6
        env:
          LIGHTHOUSE_REPORT_URL: ${{ steps.lighthouse.outputs.LIGHTHOUSE_REPORT_URL }}
        with:
          script: |
            const { LIGHTHOUSE_REPORT_URL } = process.env
            console.log(`Lighthouse report URL: ${LIGHTHOUSE_REPORT_URL}`)
            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
              body: `Check the [Lighthouse report](${LIGHTHOUSE_REPORT_URL})`
            })

For jobs​

https://docs.github.com/en/actions/using-jobs/defining-outputs-for-jobs

Artifacts​

https://github.com/actions/upload-artifact

https://github.com/actions/download-artifact

https://docs.github.com/en/actions/using-workflows/storing-workflow-data-as-artifacts

  build:
    name: Build
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: actions/setup-node@v3
        with:
          node-version: 16
      - name: Install dependencies
        run: npm ci --no-fund --omit=dev
      - name: Build
        run: npm run build
      - name: Upload build artifacts
        uses: actions/upload-artifact@v3
        with:
          name: backend
          path: |
            backend/src/build
            !backend/src/build/**/*.md
          retention-days: 5
  deploy:
    name: Deploy
    runs-on: ubuntu-latest
    steps:
      # ...
      - name: Download build artifact
        uses: actions/download-artifact@v3
        with:
          name: backend
          path: backend/src/build

Comment on a pull request​

From https://github.com/actions/github-script/blob/main/.github/workflows/pull-request-test.yml

name: Pull Request Test

on:
  pull_request:
    branches: [main]
    types: [opened, synchronize]

jobs:
  pull-request-test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: ./
        with:
          script: |
            // Get the existing comments.
            const {data: comments} = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.payload.number,
            })

            // Find any comment already made by the bot.
            const botComment = comments.find(comment => comment.user.id === 41898282)
            const commentBody = "Hello from actions/github-script! (${{ github.sha }})"

            if (context.payload.pull_request.head.repo.full_name !== 'actions/github-script') {
              console.log('Not attempting to write comment on PR from fork');
            } else {
              if (botComment) {
                await github.rest.issues.updateComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  comment_id: botComment.id,
                  body: commentBody
                })
              } else {
                await github.rest.issues.createComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number: context.payload.number,
                  body: commentBody
                })
              }
            }

https://stackoverflow.com/questions/58066966/commenting-a-pull-request-in-a-github-action

https://dev.to/zirkelc/trigger-github-workflow-for-comment-on-pull-request-45l2

JavaScript​

https://github.com/actions/github-script

OpenID Connect​

Use it to authenticate to cloud services (like AWS) without storing long-lived secrets (like access key ID and secret access key) in GitHub.

About security hardening with OpenID Connect - https://docs.github.com/en/actions/deployment/security-hardening-your-deployments/about-security-hardening-with-openid-connect

using hardcoded secrets requires you to create credentials in the cloud provider and then duplicate them in GitHub as a secret.

With OIDC, your cloud provider issues a short-lived access token that is only valid for a single job, and then automatically expires.

Configuring OpenID Connect in Amazon Web Services - https://docs.github.com/en/actions/deployment/security-hardening-your-deployments/configuring-openid-connect-in-amazon-web-services

See the examples at https://github.com/aws-actions/configure-aws-credentials/tree/master/examples. In particular see the workflow https://github.com/aws-actions/configure-aws-credentials/blob/master/examples/cfn-deploy-example/.github/workflows/deploy.yml

Creating OpenID Connect (OIDC) identity providers - https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_providers_create_oidc.html

Creating a role for a third-party Identity Provider (federation) - https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create_for-idp.html

Badge​

Adding a workflow status badge - https://docs.github.com/en/actions/monitoring-and-troubleshooting-workflows/adding-a-workflow-status-badge

Example of badge on the README: https://github.com/midudev/pokedex-for-ci/commit/04c0aa51329cd249e2283e907a33bf9ddf9da604

Badge actions on the marketplace: https://github.com/marketplace?category=&query=badge+sort%3Apopularity-desc&type=actions&verification=