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

Question

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} .

Answer 1

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

Answer 2

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