How to Publish a Lambda Layer With GitHub Actions

Zip the layer contents under the correct path, publish a new layer version, then attach it to your function.

Package the dependencies in the layer directory layout (for example nodejs/node_modules), aws lambda publish-layer-version, then attach the returned ARN with update-function-configuration --layers.

Steps

• Install dependencies under the layer path (e.g. nodejs/node_modules).
• Zip that directory into layer.zip.
• Run aws lambda publish-layer-version and capture the version ARN.
• Attach it with aws lambda update-function-configuration --layers.

Workflow

permissions:
  id-token: write
  contents: read
jobs:
  layer:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: |
          mkdir -p nodejs && cp package*.json nodejs/
          (cd nodejs && npm ci --omit=dev)
          zip -r layer.zip nodejs
      - uses: aws-actions/configure-aws-credentials@v4
        with:
          role-to-assume: arn:aws:iam::123456789012:role/gha-layer-publish
          aws-region: us-east-1
      - run: |
          ARN=$(aws lambda publish-layer-version \
            --layer-name shared-deps \
            --zip-file fileb://layer.zip \
            --compatible-runtimes nodejs20.x \
            --query 'LayerVersionArn' --output text)
          aws lambda update-function-configuration \
            --function-name my-fn --layers "$ARN"

Gotchas

• The directory layout matters: Node layers must use nodejs/node_modules, Python uses python/.
• Each publish creates a new version; functions pin a specific version ARN, not "latest".

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