In my previous articles, I covered the basics and how to control workflows. Now I want to share how to pass data between jobs and make your workflows faster with caching.<\/p>\n
Each job runs on a separate runner. This means files and variables from one job don’t automatically exist in another job. Here’s how I solved this.<\/p>\n
Outputs let you send data from one job to another. Here’s my workflow that demonstrates this:<\/p>\n
name: 12 - Working with Outputs\n\non:\n workflow_dispatch:\n inputs:\n build-status:\n type: choice\n options:\n - success\n - failure\n default: success\n\njobs:\n build:\n runs-on: ubuntu-latest\n outputs:\n build-status: ${{ steps.build.outputs.status }}\n output1: ${{ steps.build.outputs.output1 }}\n steps:\n - name: Print GITHUB_OUTPUT path\n run: echo \"$GITHUB_OUTPUT\"\n - name: Build\n id: build\n run: |\n echo \"$GITHUB_OUTPUT\"\n echo \"status=${{ inputs.build-status }}\" >> \"$GITHUB_OUTPUT\"\n echo \"output1=value1\" >> \"$GITHUB_OUTPUT\"\n echo \"output2=value2\" >> \"$GITHUB_OUTPUT\"\n cat \"$GITHUB_OUTPUT\"\n - name: Step with mistake\n run: |\n echo \"mistake=true\" > \"$GITHUB_OUTPUT\"\n cat \"$GITHUB_OUTPUT\"\n deploy:\n runs-on: ubuntu-latest\n needs: build\n if: ${{ needs.build.outputs.build-status == 'success' }}\n steps:\n - name: Deploy\n run: echo \"Deploying\"\n - name: Print Outputs\n run: |\n echo \"Output 1: ${{ needs.build.outputs.output1 }}\"<\/code><\/pre>\nHow It Works<\/h3>\n
Step 1: Set outputs in a step<\/p>\n
- name: Build\n id: build # You need this ID!\n run: |\n echo \"status=${{ inputs.build-status }}\" >> \"$GITHUB_OUTPUT\"\n echo \"output1=value1\" >> \"$GITHUB_OUTPUT\"<\/code><\/pre>\nThe $GITHUB_OUTPUT is a special file. When you write to it, GitHub captures those values.<\/p>\n
Step 2: Expose step outputs at job level<\/p>\n
jobs:\n build:\n outputs:\n build-status: ${{ steps.build.outputs.status }}\n output1: ${{ steps.build.outputs.output1 }}<\/code><\/pre>\nNotice I only exposed two outputs. output2 exists in the step but not at job level.<\/p>\n
Step 3: Use outputs in another job<\/p>\n
deploy:\n needs: build\n if: ${{ needs.build.outputs.build-status == 'success' }}\n steps:\n - name: Print Outputs\n run: echo \"Output 1: ${{ needs.build.outputs.output1 }}\"<\/code><\/pre>\nAccess outputs using needs.JOB_NAME.outputs.OUTPUT_NAME.<\/p>\n
A Common Mistake I Made<\/h3>\n
Look at this step in my workflow:<\/p>\n
- name: Step with mistake\n run: |\n echo \"mistake=true\" > \"$GITHUB_OUTPUT\" # Using > instead of >>\n cat \"$GITHUB_OUTPUT\"<\/code><\/pre>\nI used > instead of >>. The single > overwrites the file, removing all previous outputs! Always use >> to append.<\/p>\n
Why This Is Useful<\/h3>\n
I use job outputs for:<\/p>\n
- Conditional deployments:<\/strong> Only deploy if build succeeds<\/li>
- Version numbers:<\/strong> Generate version in one job, use it everywhere<\/li>
- Environment info:<\/strong> Calculate which environment to deploy to<\/li>
- Cache keys:<\/strong> Generate cache keys in one place, use them in multiple jobs<\/li><\/ul>\n
Caching: Speed Up Your Workflows<\/h3>\n
Caching saves files between workflow runs. This is huge for Node.js projects where npm install takes forever.<\/p>\n
Here’s my caching workflow for a React app:<\/p>\n
name: 13 - Using Caching\n\non:\n workflow_dispatch:\n inputs:\n use-cache:\n description: Whether to execute cache step\n type: boolean\n default: true\n node-version:\n description: Node version\n type: choice\n options:\n - 18.x\n - 20.x\n - 21.x\n default: 20.x\n\njobs:\n install-deps:\n runs-on: ubuntu-latest\n defaults:\n run:\n working-directory: react-app\n outputs:\n deps-cache-key: ${{ steps.cache-key.outputs.CACHE_KEY }}\n steps:\n - name: Checkout code\n uses: actions\/checkout@v4\n - name: Setup Node\n uses: actions\/setup-node@v4\n with:\n node-version: ${{ inputs.node-version }}\n - name: Calculate cache key\n id: cache-key\n run: |\n echo \"CACHE_KEY=deps-node-modules-${{ hashFiles('react-app\/package-lock.json') }}\" >> \"$GITHUB_OUTPUT\"\n - name: Download cached dependencies\n uses: actions\/cache@v3\n if: ${{ inputs.use-cache }}\n id: cache\n with:\n path: react-app\/node_modules\n key: ${{ steps.cache-key.outputs.CACHE_KEY }}\n - name: Install dependencies\n if: steps.cache.outputs.cache-hit != 'true'\n run: npm ci<\/code><\/pre>\nUnderstanding the Cache Key<\/h3>\n
The most important part is the cache key:<\/p>\n
- name: Calculate cache key\n id: cache-key\n run: |\n echo \"CACHE_KEY=deps-node-modules-${{ hashFiles('react-app\/package-lock.json') }}\" >> \"$GITHUB_OUTPUT\"<\/code><\/pre>\nWhat’s happening:<\/p>\n
- hashFiles() creates a hash of package-lock.json<\/li>
- If package-lock.json changes, the hash changes<\/li>
- New hash = new cache key = cache miss = fresh install<\/li>
- Same hash = cache hit = skip install<\/li><\/ul>\n
Using the Cache<\/h3>\n- name: Download cached dependencies\n uses: actions\/cache@v3\n id: cache\n with:\n path: react-app\/node_modules\n key: ${{ steps.cache-key.outputs.CACHE_KEY }}\n\n- name: Install dependencies\n if: steps.cache.outputs.cache-hit != 'true'\n run: npm ci<\/code><\/pre>\nThe actions\/cache@v3 action:<\/p>\n
- Tries to find a cache with that key<\/li>
- Sets cache-hit output to ‘true’ if found<\/li>
- If cache-hit is not ‘true’, we run npm ci<\/li><\/ul>\n
Reusing Cache in Other Jobs<\/h3>\n
Here’s how I use the same cache in multiple jobs:<\/p>\n
jobs:\n lint-test:\n runs-on: ubuntu-latest\n needs: install-deps\n defaults:\n run:\n working-directory: react-app\n steps:\n - name: Checkout code\n uses: actions\/checkout@v4\n - name: Setup Node\n uses: actions\/setup-node@v4\n with:\n node-version: ${{ inputs.node-version }}\n - name: Download cached dependencies\n uses: actions\/cache@v3\n id: cache\n with:\n path: react-app\/node_modules\n key: ${{ needs.install-deps.outputs.deps-cache-key }}\n - name: Testing\n run: npm run test\n - name: Linting\n run: echo \"Linting...\"\n build:\n runs-on: ubuntu-latest\n needs: install-deps\n defaults:\n run:\n working-directory: react-app\n steps:\n - name: Checkout code\n uses: actions\/checkout@v4\n - name: Setup Node\n uses: actions\/setup-node@v4\n with:\n node-version: ${{ inputs.node-version }}\n - name: Download cached dependencies\n uses: actions\/cache@v3\n id: cache\n with:\n path: react-app\/node_modules\n key: ${{ needs.install-deps.outputs.deps-cache-key }}\n - name: Building\n run: npm run build<\/code><\/pre>\nBoth jobs use the same cache key from install-deps job output. This means:<\/p>\n
- First job installs and caches dependencies<\/li>
- Other jobs download the cache<\/li>
- No reinstalling = faster workflows<\/li><\/ol>\n
Cache Limitations I Found<\/h3>\n
Cache size:<\/strong> Maximum 10GB per repository. GitHub deletes old caches automatically.<\/p>\nCache scope:<\/strong> Caches are scoped to branches. A cache created on main branch is not available on feature-branch.<\/p>\nCache is immutable:<\/strong> You can’t update a cache. You create a new one with a new key.<\/p>\nArtifacts: Sharing Files Between Jobs<\/h3>\n
Artifacts are files you want to keep after workflow finishes. Unlike cache, artifacts:<\/p>\n
- Survive after workflow completes<\/li>
- Can be downloaded from GitHub UI<\/li>
- Are meant for build outputs, test results, logs<\/li><\/ul>\n
Here’s my complete workflow:<\/p>\n
name: 14 - Working with Artifacts\n\non: workflow_dispatch\n\nenv:\n build-artifact-key: app-${{ github.sha }}\n test-coverage-key: test-coverage-${{ github.sha }}\n\njobs:\n test-build:\n runs-on: ubuntu-latest\n defaults:\n run:\n working-directory: react-app\n steps:\n - name: Checkout code\n uses: actions\/checkout@v4\n - name: Setup Node\n uses: actions\/setup-node@v4\n with:\n node-version: '20.x'\n - name: Download cached dependencies\n uses: actions\/cache@v3\n id: cache\n with:\n path: react-app\/node_modules\n key: deps-node-modules-${{ hashFiles('react-app\/package-lock.json') }}\n - name: Install dependencies\n if: steps.cache.outputs.cache-hit != 'true'\n run: npm ci\n - name: Unit tests\n run: npm run test -- --coverage\n - name: Upload test results\n uses: actions\/upload-artifact@v4\n with:\n name: ${{ env.test-coverage-key }}\n path: react-app\/coverage\n - name: Build code\n run: npm run build\n - name: Upload build files\n uses: actions\/upload-artifact@v4\n with:\n name: ${{ env.build-artifact-key }}\n path: react-app\/build\n deploy:\n runs-on: ubuntu-latest\n needs: test-build\n steps:\n - name: Download build artifact\n uses: actions\/download-artifact@v4\n with:\n name: ${{ env.build-artifact-key }}\n path: build\n - name: Show folder structure\n run: ls -R<\/code><\/pre>\nUploading Artifacts<\/h3>\n- name: Upload build files\n uses: actions\/upload-artifact@v4\n with:\n name: ${{ env.build-artifact-key }}\n path: react-app\/build<\/code><\/pre>\nThis uploads everything in react-app\/build directory with a unique name using commit SHA.<\/p>\n
Downloading Artifacts<\/h3>\n- name: Download build artifact\n uses: actions\/download-artifact@v4\n with:\n name: ${{ env.build-artifact-key }}\n path: build<\/code><\/pre>\nDownloads the artifact to build directory in the deploy job.<\/p>\n
Using github.sha for Unique Names<\/h3>\nenv:\n build-artifact-key: app-${{ github.sha }}\n test-coverage-key: test-coverage-${{ github.sha }}<\/code><\/pre>\nI use github.sha (commit hash) to make artifact names unique. Each commit gets its own artifacts.<\/p>\n
Cache vs Artifacts: When to Use What<\/h3>\n
Use Cache for:<\/p>\n
- Dependencies (node_modules, pip packages)<\/li>
- Things you can regenerate<\/li>
- Speeding up workflows<\/li>
- Data you don’t need after workflow finishes<\/li><\/ul>\n
Use Artifacts for:<\/p>\n
- Build outputs (compiled code, docker images)<\/li>
- Test results and coverage reports<\/li>
- Logs and debug information<\/li>
- Files you want to download from GitHub UI<\/li>
- Data you need to deploy<\/li><\/ul>\n
Real-World Example: Combining Everything<\/h3>\n
Here’s how I use all three concepts together:<\/p>\n
name: Complete CI\/CD Pipeline\n\non:\n push:\n branches: [main]\n\nenv:\n NODE_VERSION: '20.x'\n\njobs:\n install-and-cache:\n runs-on: ubuntu-latest\n outputs:\n cache-key: ${{ steps.cache-key.outputs.key }}\n steps:\n - uses: actions\/checkout@v4\n - uses: actions\/setup-node@v4\n with:\n node-version: ${{ env.NODE_VERSION }}\n - name: Generate cache key\n id: cache-key\n run: echo \"key=deps-${{ hashFiles('**\/package-lock.json') }}\" >> \"$GITHUB_OUTPUT\"\n - uses: actions\/cache@v3\n id: cache\n with:\n path: node_modules\n key: ${{ steps.cache-key.outputs.key }}\n - if: steps.cache.outputs.cache-hit != 'true'\n run: npm ci\n test:\n needs: install-and-cache\n runs-on: ubuntu-latest\n steps:\n - uses: actions\/checkout@v4\n - uses: actions\/setup-node@v4\n with:\n node-version: ${{ env.NODE_VERSION }}\n - uses: actions\/cache@v3\n with:\n path: node_modules\n key: ${{ needs.install-and-cache.outputs.cache-key }}\n - run: npm run test -- --coverage\n - uses: actions\/upload-artifact@v4\n with:\n name: coverage-${{ github.sha }}\n path: coverage\n build:\n needs: [install-and-cache, test]\n runs-on: ubuntu-latest\n outputs:\n build-success: ${{ steps.build.outputs.success }}\n steps:\n - uses: actions\/checkout@v4\n - uses: actions\/setup-node@v4\n with:\n node-version: ${{ env.NODE_VERSION }}\n - uses: actions\/cache@v3\n with:\n path: node_modules\n key: ${{ needs.install-and-cache.outputs.cache-key }}\n - name: Build\n id: build\n run: |\n npm run build\n echo \"success=true\" >> \"$GITHUB_OUTPUT\"\n - uses: actions\/upload-artifact@v4\n with:\n name: build-${{ github.sha }}\n path: build\n deploy:\n needs: build\n if: needs.build.outputs.build-success == 'true'\n runs-on: ubuntu-latest\n steps:\n - uses: actions\/download-artifact@v4\n with:\n name: build-${{ github.sha }}\n path: dist\n - name: Deploy\n run: echo \"Deploying files from dist\/\"<\/code><\/pre>\nThis workflow:<\/p>\n
- Installs and caches dependencies once<\/li>
- Test and build jobs reuse the cache<\/li>
- Test results are saved as artifacts<\/li>
- Build output is saved as artifacts<\/li>
- Deploy job downloads build artifacts<\/li>
- Deploy only runs if build succeeded (using job outputs)<\/li><\/ol>\n
What I Learned<\/h3>\n- Always use >> for GITHUB_OUTPUT:<\/strong> Using > will delete previous outputs.<\/li>
- Job outputs don’t need to match step outputs:<\/strong> You can pick which step outputs to expose at job level.<\/li>
- Cache keys are critical:<\/strong> Use hashFiles() to make cache keys change when dependencies change.<\/li>
- Cache early in your workflow:<\/strong> Install dependencies in the first job, cache them, and all other jobs can use that cache.<\/li>
- Artifacts cost storage:<\/strong> GitHub gives you free storage, but artifacts count against it. They expire after 90 days by default.<\/li>
- Use github.sha for uniqueness:<\/strong> It’s perfect for creating unique artifact names for each commit.<\/li>
- Working directory matters:<\/strong> When using actions\/cache, make sure the path is correct. I use defaults.run.working-directory to avoid mistakes.<\/li><\/ol>","protected":false},"excerpt":{"rendered":"
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