GitHub Actions: How to get contents of VERSION file into environment variable?

user_10984961 0
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In my Docker project's repo, I have a VERSION file that contains nothing more than the version number.

1.2.3

In Travis, I'm able to cat the file to an environment variable, and use that to tag my build before pushing to Docker Hub.

---
env:
  global:
    - USER=username
    - REPO=my_great_project
    - VERSION=$(cat VERSION)

What is the equivalent of that in GitHub Actions? I tried this, but it's not working.

name: Test

on:
  ...
  ...

env:
  USER: username
  REPO: my_great_project

jobs:
  build_ubuntu:
    name: Build Ubuntu

    runs-on: ubuntu-latest
    env:
      BASE: ubuntu

    steps:
    - name: Check out the codebase
      uses: actions/checkout@v2

    - name: Build the image
      run: |
        VERSION=$(cat VERSION)
        docker build --file ${BASE}/Dockerfile --tag ${USER}/${REPO}:${VERSION} .

  build_alpine:
    name: Build Alpine

    runs-on: ubuntu-latest
    env:
      BASE: alpine

    ...
    ...
    ...

I've also tried this, which doesn't work.

- name: Build the image
  run: |
    echo "VERSION=$(cat ./VERSION)" >> $GITHUB_ENV
    docker build --file ${BASE}/Dockerfile --tag ${USER}/${REPO}:${VERSION} .
github-actions docker
2 Answers

I went down the road that Benjamin W. was talking about with having VERSION in my environment vs just in that specific step.

This worked for me to set the variable in one step, then use it in separate steps.

- name: Set variables
  run: |
    VER=$(cat VERSION)
    echo "VERSION=$VER" >> $GITHUB_ENV

- name: Build Docker Image
  uses: docker/build-push-action@v2
  with:
    context: .
    file: ${{ env.BASE_DIR }}/Dockerfile
    load: true
    tags: |
      ${{ env.USER }}/${{ env.REPO }}:${{ env.VERSION }}
      ${{ env.USER }}/${{ env.REPO }}:latest
user_109849610

As I want to re-use ENV_VAR between jobs, this is how I do it. I wish I could find a way to minimize this code.

In this example, I use VARs from my Dockerfile. But it will work from any file.

  pre_build:
    runs-on: ubuntu-20.04
    steps:
        ...
      -
        name: Save variables to disk
        run: |
          cat $(echo ${{ env.DOCKERFILE }}) | grep DOCKERHUB_USER= | head -n 1 | grep -o '".*"' | sed 's/"//g' > ~/varz/DOCKERHUB_USER
          cat $(echo ${{ env.DOCKERFILE }}) | grep GITHUB_ORG= | head -n 1 | grep -o '".*"' | sed 's/"//g' > ~/varz/GITHUB_ORG
          cat $(echo ${{ env.DOCKERFILE }}) | grep GITHUB_REGISTRY= | head -n 1 | grep -o '".*"' | sed 's/"//g' > ~/varz/GITHUB_REGISTRY
          echo "$(cat ~/varz/DOCKERHUB_USER)/$(cat ~/varz/APP_NAME)" > ~/varz/DKR_PREFIX
      - 
        name: Set ALL variables for this job | à la sauce GitHub Actions
        run: |
          echo "VERSION_HASH_DATE=$(cat ~/varz/VERSION_HASH_DATE)" >> $GITHUB_ENV
          echo "VERSION_HASH_ONLY=$(cat ~/varz/VERSION_HASH_ONLY)" >> $GITHUB_ENV
          echo "VERSION_CI=$(cat ~/varz/VERSION_CI)" >> $GITHUB_ENV
          echo "VERSION_BRANCH=$(cat ~/varz/VERSION_BRANCH)" >> $GITHUB_ENV
      -
        name: Show variables
        run: |
          echo "${{ env.VERSION_HASH_DATE }} < VERSION_HASH_DATE"
          echo "${{ env.VERSION_HASH_ONLY }} < VERSION_HASH_ONLY"
          echo "${{ env.VERSION_CI }} < VERSION_CI"
          echo "${{ env.VERSION_BRANCH }} < VERSION_BRANCH"
      - 
        name: Upload variables as artifact
        uses: actions/upload-artifact@master
        with:
          name: variables_on_disk
          path: ~/varz

  test_build:
    needs: [pre_build]
    runs-on: ubuntu-20.04
    steps:
       ...
      - 
        name: Job preparation | Download variables from artifact
        uses: actions/download-artifact@master
        with:
          name: variables_on_disk
          path: ~/varz
      - 
        name: Job preparation | Set variables for this job | à la sauce GitHub Actions
        run: |
          echo "VERSION_HASH_DATE=$(cat ~/varz/VERSION_HASH_DATE)" >> $GITHUB_ENV
          echo "VERSION_HASH_ONLY=$(cat ~/varz/VERSION_HASH_ONLY)" >> $GITHUB_ENV
          echo "VERSION_BRANCH=$(cat ~/varz/VERSION_BRANCH)" >> $GITHUB_ENV
          echo "BRANCH_NAME=$(cat ~/varz/BRANCH_NAME)" >> $GITHUB_ENV
user_55962890
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