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

Relevant: https://docs.github.com/en/actions/reference/workflow-commands-for-github-actions#setting-an-environment-variable and: https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/ — 0 _, Jun 18 '21 at 23:59
Using outputs with matrix jobs https://github.com/orgs/community/discussions/25634 — Richard Tyler Miles, Sep 11 '22 at 06:06

peterevans · Accepted Answer · 2022-11-04T07:20:03.663

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. Also, the step returning outputs should have an id, which is referred to by the step consuming the outputs.

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 "docker_tag=$(echo ${GITHUB_REF} | cut -d'/' -f3)-${GITHUB_SHA}" >> $GITHUB_OUTPUT
      - name: Docker Build
        uses: "actions/docker/cli@master"
        with:
          args: build . --file Dockerfile -t cflynnus/blog:${{ 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: |
          pr_title="[Test] Add report file $(date +%d-%m-%Y)"
          pr_body="This PR was auto-generated on $(date +%d-%m-%Y) \
            by [create-pull-request](https://github.com/peter-evans/create-pull-request)."
          echo "pr_title=$pr_title" >> $GITHUB_OUTPUT
          echo "pr_body=$pr_body" >> $GITHUB_OUTPUT
      - name: Create Pull Request
        uses: peter-evans/create-pull-request@v4
        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@v4
        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.

Just to be clear, these solutions do not work between steps of _different jobs_ — grokpot, Mar 31 '20 at 08:53
Are this solutions deprecated? https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/ — Sandburg, Oct 13 '21 at 16:09
@Sandburg No they are not deprecated. These solutions show the current way to create step outputs and environment variables. — peterevans, Oct 14 '21 at 00:01
@grokpot outputs across different jobs also seem to be supported, but you need to forward the step output to the job output: https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idoutputs — MakisH, Jan 28 '22 at 08:34
Thanks! Not using quotes was the answer for me. `echo '::set-output $(date +%s) ...'` does not work but `echo ::set-output $(date +%s)...` works for substitute values. — NecipAllef, Jul 15 '22 at 14:49
@NecipAllef This is because (in shells in general) single quotes prevent parameter expansion. Using double quotes (`""`) would also work. — FWDekker, Feb 28 '23 at 17:31

score 15 · Answer 2 · answered Mar 07 '23 at 07:42

15

set-output has been depreciated and the better way to do this is now:

echo "{name}={value}" >> $GITHUB_OUTPUT

Example from Github docs:

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

answered Mar 07 '23 at 07:42

Vadim Peretokin

2,221
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also notice that it's "SELECTED_COLOR=green" without any *space* in the beginning, because I was struggling with an output var that has a space in the beginning >" SELECTED_COLOR=green". – Bachiri Taoufiq Abderrahman Jul 31 '23 at 08:46

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

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