Github Actions, how to share a calculated value between job steps?

Question

Is there a DRY way to calculate and share a value in multiple job steps with Github Actions?

In the below workflow yml file, echo ${GITHUB_REF} | cut -d'/' -f3`-${GITHUB_SHA} is repeated in multiple steps.

name: Test, Build and Deploy on:   push:     branches:       - master jobs:   build_and_push:     name: Build and Push     runs-on: ubuntu-latest     steps:       - name: Docker Build         uses: "actions/docker/cli@master"         with:           args: build . --file Dockerfile -t cflynnus/blog:`echo ${GITHUB_REF} | cut -d'/' -f3`-${GITHUB_SHA}       - name: Docker Tag Latest         uses: "actions/docker/cli@master"         with:           args: tag cflynnus/blog:`echo ${GITHUB_REF} | cut -d'/' -f3`-${GITHUB_SHA} cflynnus/blog:latest 

Answer 1

set-output can be used to define outputs for steps. The outputs can then be used in later steps and evaluated in with and env input sections.

The following is what that would look like for your example.

name: Test, Build and Deploy on:   push:     branches:       - master jobs:   build_and_push:     name: Build and Push     runs-on: ubuntu-latest     steps:       - name: Set tag var         id: vars         run: echo ::set-output name=docker_tag::$(echo ${GITHUB_REF} | cut -d'/' -f3)-${GITHUB_SHA}       - name: Docker Build         uses: "actions/docker/cli@master"         with:           args: build . --file Dockerfile -t cflynnus/blog:${{ steps.vars.outputs.docker_tag }}       - name: Docker Tag Latest         uses: "actions/docker/cli@master"         with:           args: tag cflynnus/blog:${{ steps.vars.outputs.docker_tag }} cflynnus/blog:latest 

Here is another example showing how to dynamically set multiple variables to be used by an action.

      - name: Set output variables         id: vars         run: |           echo ::set-output name=pr_title::"[Test] Add report file $(date +%d-%m-%Y)"           echo ::set-output name=pr_body::"This PR was auto-generated on $(date +%d-%m-%Y) \             by [create-pull-request](https://github.com/peter-evans/create-pull-request)."       - name: Create Pull Request         uses: peter-evans/create-pull-request@v2         with:           title: ${{ steps.vars.outputs.pr_title }}           body: ${{ steps.vars.outputs.pr_body }} 

Alternatively you can create environment variables.

      - name: Set environment variables         run: |           echo "PR_TITLE=[Test] Add report file $(date +%d-%m-%Y)" >> $GITHUB_ENV           echo "PR_BODY=This PR was auto-generated on $(date +%d-%m-%Y) by [create-pull-request](https://github.com/peter-evans/create-pull-request)." >> $GITHUB_ENV       - name: Create Pull Request         uses: peter-evans/create-pull-request@v2         with:           title: ${{ env.PR_TITLE }}           body: ${{ env.PR_BODY }} 

Update: The docker actions in the first example are deprecated. Please see this answer for the latest way to work with docker in GitHub Actions.

Note: For sharing values between different jobs, see this question.