Github actions 기초

Introduction

Github actions는 push, issue 등록, PR merge 등 특정 이벤트가 발생했을 때 runner를 이용해 규정한 동작을 해주는 기능이다.

Getting Started

Github repository를 하나 만들어보자.

Actions 탭에 들어간 뒤 configure 버튼을 클릭해보자.

repo/.github/workflow/01-main.yml

# action의 이름
name: Hello World!

# 어떤 event가 발생할 때 동작할 것인가
on: [push]

jobs:
  build:
    # runner
    runs-on: ubuntu-latest

    steps:
    - name: Run pwd
      run: pwd
    - name: Run ls -al
      run: ls -al

Code 탭으로 돌어가보면 .github/workflow/01-main.yml 이 생성되었음을 확인할 수 있다.

이제 repository를 로컬로 clone 하자.

Github checkout

.github/workflow/github-checkout.yml을 생성하자.

02-github-checkout.yml

# action의 이름
name: Github Checkout

# 어떤 event가 발생할 때 동작할 것인가
on: [push]

jobs:
  build:
    # runner
    runs-on: ubuntu-latest

    steps:
    # uses: 다른 사람이 만든 action을 사용한다.
    # actions/checkout@v3: 현재 repository를 git clone하고 checkout 해준다.
    # https://github.com/actions/checkout 또는 Marketplace
    - uses: actions/checkout@v3	
    - name: Run pwd
      run: pwd
    - name: Run ls -al
      run: ls -al

이제 Actions 탭에서 Github Checkout 액션의 빌드 내용을 확인해보자.

우리의 github repository가 잘 clone, checkout 되었음을 확인할 수 있다.

Context

03-context.yml

# This is a basic workflow to help you get started with Actions

name: Context

# Controls when the workflow will run
on: [push]

# A workflow run is made up of one or more jobs that can run sequentially or in parallel
jobs:
  # This workflow contains a single job called "build"
  build:
    # The type of runner that the job will run on
    runs-on: ubuntu-latest

    # Steps represent a sequence of tasks that will be executed as part of the job
    steps:
      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
      - name: "context"
        env:
          COMMIT_ID: ${{ github.sha }}
        run: echo "Commit ID = $COMMIT_ID"

context는 ${{ <context> }} 문법으로 사용할 수 있다.

github는 github, env, job, steps, runner, secrets 등 다양한 context를 제공한다.

예를 들어, github.sha는 workflow를 trigger한 commit의 SHA를 의미한다.

context를 사용하면 runner에게 다양한 정보를 전달할 수 있다.

secrets

Settings > Secrets > Actions 에 들어가서 New repository secret 버튼을 눌러보자.

PASSWORD라는 이름의 secret을 추가한 뒤 새로운 workflow를 생성해보자.

04-secrets.yml

# This is a basic workflow to help you get started with Actions

name: Secrets

# Controls when the workflow will run
on: [push]

# A workflow run is made up of one or more jobs that can run sequentially or in parallel
jobs:
  # This workflow contains a single job called "build"
  build:
    # The type of runner that the job will run on
    runs-on: ubuntu-latest

    # Steps represent a sequence of tasks that will be executed as part of the job
    steps:
      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
      - name: Print Password
        env:
          PASSWORD: ${{ secrets.PASSWORD }}
        run: echo "secrets.PASSWORD = $PASSWORD"

내가 입력한 비밀번호는 가려진 채로 표시된다.

Bash Shell Commands 적용하기

05-run-sh.yml

# This is a basic workflow to help you get started with Actions

name: Run sh file

# Controls when the workflow will run
on:
  push:
    branches: [main]

# A workflow run is made up of one or more jobs that can run sequentially or in parallel
jobs:
  # This workflow contains a single job called "build"
  build:
    # The type of runner that the job will run on
    runs-on: ubuntu-latest

    # Steps represent a sequence of tasks that will be executed as part of the job
    steps:
      - uses: actions/checkout@v3

      - name: "쉘 스크립트 실행"
        run: sh ./shell-commands/05-run-sh.sh

shell-commands/05-run-sh.sh

echo 현재 경로
pwd
echo 파일 목록
ls -al
echo 자바가 설치되어 있나요?
java -version
echo Git이 설치되어 있나요?
git --version
echo Build tool이 설치되어 있나요?
mvn --version
gradle --version
ant -version

의외로(?) Java 관련 툴들은 이미 설치가 되어 있다.

Multi-step Github Actions

step을 여러 개로 나눠두면 코드를 볼 때 뿐만 아니라 빌드 결과를 볼 때도 가독성이 더 좋다.

Multi-job Github Actions

07-multi-job

# This is a basic workflow to help you get started with Actions

name: Run sh file

# Controls when the workflow will run
on:
	push:
		branches: [main]

# A workflow run is made up of one or more jobs that can run sequentially or in parallel
jobs:
  # This workflow contains a single job called "build"
  build-on-windows:
    # The type of runner that the job will run on
    runs-on: windows-latest

    # Steps represent a sequence of tasks that will be executed as part of the job
    steps:
      - uses: actions/checkout@v3

      - name: "windows에서 쉘 스크립트 실행"
        run: sh ./shell-commands/07-multi-job-windows.sh

	build-on-ubuntu:
    # The type of runner that the job will run on
    runs-on: ubuntu-latest

    # Steps represent a sequence of tasks that will be executed as part of the job
    steps:
      - uses: actions/checkout@v3

      - name: "ubuntu에서 쉘 스크립트 실행"
        run: sh ./shell-commands/07-multi-job-ubuntu.sh

여러 runner에게 서로 다른 작업을 맡길 수도 있다.

중요한 점은 각각의 job이 서로 다른 runner에 의해 병렬적으로 처리된다는 것이다.

배포 서버를 runner로 사용하기

1. 레포지토리 > Settings > Actions > Runners > Create self-hosted runner

2. 배포 서버의 architecture 명시

   

3. 배포 서버에서 runner application 설치

   

Artifacts

artifact 라는 형태로 데이터를 Github에 upload, download 하면서 job 끼리 데이터를 교환하는 것도 가능하다.

name: Share data between jobs

on: [push]

jobs:
  job_1:
    name: Add 3 and 7
    runs-on: ubuntu-latest
    steps:
      - shell: bash
        run: |
          expr 3 + 7 > math-homework.txt
      - name: Upload math result for job 1
        uses: actions/upload-artifact@v3
        with:
          name: homework
          path: math-homework.txt

  job_2:
    name: Multiply by 9
    needs: job_1
    runs-on: windows-latest
    steps:
      - name: Download math result for job 1
        uses: actions/download-artifact@v3
        with:
          name: homework
      - shell: bash
        run: |
          value=`cat math-homework.txt`
          expr $value \* 9 > math-homework.txt
      - name: Upload math result for job 2
        uses: actions/upload-artifact@v3
        with:
          name: homework
          path: math-homework.txt

  job_3:
    name: Display results
    needs: job_2
    runs-on: macOS-latest
    steps:
      - name: Download math result for job 2
        uses: actions/download-artifact@v3
        with:
          name: homework
      - name: Print the final result
        shell: bash
        run: |
          value=`cat math-homework.txt`
          echo The result is $value

needs 커맨드로 job이 순차적으로 이루어지도록 설정한 점을 주목하자.

References

[1] 생활코딩 Github actions 강의

[2] Master Github actions Tutorial

[3] 공식 문서 - adding-self-hosted runners

[4] 공식 문서 - sharing data between job

[5] 공식 문서 - storing workflow data as artifacts