Trigger GitHub Actions Workflow from Another Workflow with Inputs, Outputs, and Secrets

Introduction

GitHub Actions is a powerful feature that lets developers automate, customize, and execute their software development workflows right in their repositories. One of the common practices is to trigger one workflow from another, which allows for better segmentation and control over complex workflow processes. This blog post will guide you on triggering a GitHub Actions workflow from another, passing inputs, outputs, and secrets between them.

GitHub Actions Overview

GitHub Actions provides an automation platform where workflows, defined in YAML files, respond to various repository events. Workflows can be simple, performing tasks like code linting, or more complex, handling build, test, and deployment processes.

Triggering a Workflow from Another

The key to triggering one workflow from another lies in the workflow_run event. Let’s break down how to set up one workflow to trigger another, passing inputs, outputs, and secrets.

Step 1: Create Workflow YAML Files

Start by creating two new YAML files within the .github/workflows directory in your repository. Let’s name them first-workflow.yml and second-workflow.yml.

Step 2: Define the First Workflow

In first-workflow.yml, define a simple job that sets an output. This output will later be used by the second workflow.

name: First Workflow

on: 
  push:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - name: Set output
      id: step1
      run: |
        echo "This is the first workflow"
        echo "::set-output name=timestamp::$(date +%s)"
    outputs:
      timestamp: ${{ steps.step1.outputs.timestamp }}

name: First Workflow

on:

push:

branches:

- main

jobs:

build:

runs-on: ubuntu-latest

steps:

- name: Set output

id: step1

run: |

echo "This is the first workflow"

echo "::set-output name=timestamp::$(date +%s)"

outputs:

timestamp: ${{ steps.step1.outputs.timestamp }}

Step 3: Define the Second Workflow

In second-workflow.yml, define a job that is triggered by the workflow_run event. It then prints the output from the first workflow.

name: Second Workflow

on: 
  workflow_run:
    workflows: ["First Workflow"]
    types: 
      - completed

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - name: Get output from first workflow
      id: workflow_run
      uses: actions/github-script@v5
      with:
        script: |
          const runId = context.payload.workflow_run.id
          const artifactClient = github.getArtifactOctokit()
          const artifacts = await artifactClient.rest.actions.listWorkflowRunArtifacts({
            owner: context.repo.owner,
            repo: context.repo.repo,
            run_id: runId,
          })
          return artifacts.data.artifacts[0].archive_download_url
        result-orientation: verbose
        token: ${{ secrets.GITHUB_TOKEN }}
    - name: Download artifact
      run: |
        wget "${{ steps.workflow_run.outputs.result }}"

name: Second Workflow

on:

workflow_run:

workflows: ["First Workflow"]

types:

- completed

jobs:

build:

runs-on: ubuntu-latest

steps:

- name: Get output from first workflow

id: workflow_run

uses: actions/github-script@v5

with:

script: |

const runId = context.payload.workflow_run.id

const artifactClient = github.getArtifactOctokit()

const artifacts = await artifactClient.rest.actions.listWorkflowRunArtifacts({

owner: context.repo.owner,

repo: context.repo.repo,

run_id: runId,

})

return artifacts.data.artifacts[0].archive_download_url

result-orientation: verbose

token: ${{ secrets.GITHUB_TOKEN }}

- name: Download artifact

run: |

wget "${{ steps.workflow_run.outputs.result }}"

Here, the second workflow is triggered when the first workflow is completed. It then uses the github-script action to fetch the output from the first workflow. Note that the GITHUB_TOKEN secret is used for authentication.

Conclusion

GitHub Actions offers great flexibility and control in CI/CD pipeline setup. Triggering one workflow from another provides better organization and segmentation of complex workflows, and the ability to pass inputs, outputs, and secrets between workflows allows for secure and effective pipeline management.

While this guide outlines a basic example, real-world workflows may involve more complex tasks like building applications, running tests, and deploying code to various environments. GitHub Actions offers endless possibilities to create efficient and flexible pipelines, customized to your project’s needs.