Ubuntu - GitHub Action Output Environment Variable from Child Template

delarooster
September 18, 2023
113 views
0 votes
2 Answers

I have already posted this question on GitHub Actions Community but any involvement seems to have petered out there.

I’m attempting to extract an output from a child workflow in a subsequent parent job and having zero luck getting anything to properly formulate. Latest hard-coded attempt:

parent workflow:

jobs:
  jobA:
    uses: [...]/.github/workflows/deploy-bicep.yaml@main
  
  jobB:
    runs-on: ubuntu-latest
    needs: jobA
    defaults:
      run:
        shell: pwsh
    steps:
      - run: |
          Write-Host "ACR Name -> " ${{ needs.jobA.outputs.acrName }}

child workflow (called from jobA):

jobs:
  deploy-bicep:
    runs-on: ${{ inputs.vmImage }}
    defaults:
      run:
        shell: pwsh
    steps:
      - name: Hard-Coded Outputs
        id: bicep-outputs
        run: |
          $outputs = "acrName=Blah123"
          echo "Hard-coded outputs: $outputs"
          echo $outputs | Out-File -Append $env:GITHUB_OUTPUT
    outputs: 
      acrName: ${{ steps.bicep-outputs.outputs.acrName }}

As many times before, the result from the second iteration of jobB is an empty string.

Anyone else have any suggestions? Trying to migrate from Azure YAML Pipelines and despite Actions being a fork of the former there are definitely some functionality gaps.

Thanks!

Answers

Chosen as BEST ANSWER
- delarooster
- September 5, 2023 at 3:41 pm
- 0 votes
0
Answered on the GitHub Actions board and placing here for others (easier) reference:

With the vast limitations of having to hard-code outputs from a child workflow to its parent, and then that parent workflow having to have hard-coded output references I ended up creating individual files in an outputs/ folder and publishing the outputs folder to the artifact directory, such as the following:
```
- run: |
    Set-Content -Path bicep-outputs/$($name) -Value $($out.$name.value)

- uses: actions/upload-artifact@v3
        with:
          name: bicep-outputs
          path: bicep-outputs/
```
In which the second job in the calling workflow can easily download such artifact and read them whenever necessary. Much more decoupled and manageable than the prescribed method of using "outputs" ->
```
steps:
      - uses: actions/download-artifact@v3
        with:
          name: bicep-outputs
          path: bicep-outputs
          
      - name: Display structure of downloaded files
        run: ls -R

      - run: |
          Write-Host "ACR Name -> " $(Get-Content -Path bicep-outputs/acrName)
```
Passing variables between jobs on the same plane appears just fine, but still, creating variables dynamically without specific references for consumption by later steps and jobs, no matter the plane of the workflow, seems to be a feature-miss from the fork of Azure Pipelines.
Or perhaps intentional? Either way thankfully the above works as expected.

(Edit)

- Azeem
- August 25, 2023 at 8:50 am
- 0 votes
0
In the context of reusable workflows, the official terms are "caller" and "called" workflows, not "parent" and "child".

For your specific problem, the on.workflow_call.outputs section is missing to propagate output parameters from the "called" workflow.

on.workflow_call.outputs

A map of outputs for a called workflow. Called workflow outputs are available to all downstream jobs in the caller workflow. Each output has an identifier, an optional description, and a value. The value must be set to the value of an output from a job within the called workflow.

Also, see using outputs from a reusable workflow for more details.

Here’s a simple example emulating your scenario:

.github/workflows/reusable_workflow_set_output.yml
```
name: reusable_workflow_set_output

on:
  workflow_call:
    outputs:
      test:
        value: '${{ jobs.set.outputs.test }}'

jobs:
  set:
    runs-on: windows-latest

    defaults:
      run:
        shell: pwsh

    outputs:
      test: '${{ steps.set.outputs.test }}'

    steps:
    - name: Set
      id: set
      run: |
        $output="test=123"
        echo "output: $output"
        echo $output >> $env:GITHUB_OUTPUT

    - name: Get
      run: |
        echo "test: ${{ steps.set.outputs.test }}"
```
.github/workflows/reusable_workflow_set_output_caller.yml
```
name: reusable_workflow_set_output_caller

on: workflow_dispatch

jobs:
  set:
    uses: ./.github/workflows/reusable_workflow_set_output.yml

  get:
    needs: set
    runs-on: windows-latest

    defaults:
      run:
        shell: pwsh

    steps:
    - name: Get
      run: |
        echo "test: ${{ needs.set.outputs.test }}"
```
Output:
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