Objective

A repository at /home/interview/repo contains multiple applications that share common build steps. The team wants to eliminate duplication by creating a centralized reusable workflow. The repository has the upload-artifact action available locally at .github/actions/upload-artifact.

Task

Complete two workflows. First, complete the reusable workflow at .github/workflows/shared-build.yml that accepts an input parameter app-name (type: string), uses container image node:20-slim, runs ./build.sh with the app name, and uploads a build artifact named build-<app-name>. Second, complete the caller workflow at .github/workflows/deploy.yml that triggers on push and calls the reusable workflow with app-name: "frontend".

File Path

• Reusable workflow: /home/interview/repo/.github/workflows/shared-build.yml
• Caller workflow: /home/interview/repo/.github/workflows/deploy.yml
• Build script: /home/interview/repo/build.sh

name: Shared Build Workflow

on:
  workflow_call:
    inputs:
      app-name:
        required: true
        type: string

jobs:
  build:
    runs-on: ubuntu-latest
    container:
      image: node:20-slim

    steps:
      - uses: actions/checkout@v4

      - name: Run build script
        run: ./build.sh ${{ inputs.app-name }}

      - name: Upload build artifact
        uses: ./.github/actions/upload-artifact
        with:
          name: build-${{ inputs.app-name }}
          path: build-output.txt

Caller workflow (deploy.yml):

name: Deploy Workflow

on:
  push:

jobs:
  call-build:
    uses: ./.github/workflows/shared-build.yml
    with:
      app-name: "frontend"

Explanation

Step 1: Reusable Workflow Trigger

on:
  workflow_call:
    inputs:
      app-name:
        required: true
        type: string

workflow_call makes this a reusable workflow. It can't be triggered directly by events like push. Instead, other workflows call it. The inputs block defines parameters the caller must provide. app-name is required and must be a string.

Step 2: Using Input in Steps

- name: Run build script
  run: ./build.sh ${{ inputs.app-name }}

- name: Upload build artifact
  uses: ./.github/actions/upload-artifact
  with:
    name: build-${{ inputs.app-name }}
    path: build-output.txt

${{ inputs.app-name }} reads the value passed by the caller. If the caller sends "frontend", the build script runs as ./build.sh frontend and the artifact is named build-frontend.

Step 3: Caller Workflow

jobs:
  call-build:
    uses: ./.github/workflows/shared-build.yml
    with:
      app-name: "frontend"

The caller uses uses: with the path to the reusable workflow (not a step action, but a workflow file). The with block passes the input parameters. Multiple callers can reuse the same workflow with different app names.