sbom.yml

name: Generate SBOM

# Generates and attaches an SPDX SBOM to the GitHub release for the pushed
# version tag.  Runs only on vX.Y.Z tag pushes; the SBOM asset is uploaded
# (or replaced) via the GitHub Releases API.  Idempotent: if the asset
# already exists it is deleted and re-uploaded with fresh scan output.

on:
  push:
    tags:
      - "v*"

permissions: {}

concurrency:
  group: sbom-${{ github.ref }}
  cancel-in-progress: false

jobs:
  generate-sbom:
    name: Generate and Attach SBOM
    runs-on: ubuntu-latest
    timeout-minutes: 30
    permissions:
      contents: write # upload SBOM asset to the GitHub release

    steps:
      - name: Checkout code
        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
        with:
          persist-credentials: false

      - name: Install Syft (pinned version with checksum verification)
        env:
          SYFT_VERSION: "1.41.0"
        run: |
          curl -sSfL -o syft.tar.gz \
            "https://github.com/anchore/syft/releases/download/v${SYFT_VERSION}/syft_${SYFT_VERSION}_linux_amd64.tar.gz"
          curl -sSfL -o syft_checksums.txt \
            "https://github.com/anchore/syft/releases/download/v${SYFT_VERSION}/syft_${SYFT_VERSION}_checksums.txt"
          # Verify the downloaded archive against the published checksum for this exact asset.
          EXPECTED=$(awk '$2 == "syft_'${SYFT_VERSION}'_linux_amd64.tar.gz" {print $1}' syft_checksums.txt)
          echo "${EXPECTED}  syft.tar.gz" | sha256sum -c -
          tar -xzf syft.tar.gz syft
          sudo mv syft /usr/local/bin/syft
          rm -f syft.tar.gz syft_checksums.txt

      - name: Generate SBOM (SPDX format)
        run: |
          syft . -o spdx-json=sbom.spdx.json

      - name: Find release ID for the pushed tag
        id: release
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          TAG_NAME="${GITHUB_REF#refs/tags/}"
          RELEASE_ID=$(curl -s -H "Authorization: token ${GITHUB_TOKEN}" \
            "https://api.github.com/repos/${GITHUB_REPOSITORY}/releases/tags/${TAG_NAME}" \
            | jq -r '.id')

          if [ -z "${RELEASE_ID}" ] || [ "${RELEASE_ID}" = "null" ]; then
            echo "release_id=" >> "${GITHUB_OUTPUT}"
          else
            echo "release_id=${RELEASE_ID}" >> "${GITHUB_OUTPUT}"
          fi

      - name: Check for existing SBOM asset and upload
        if: steps.release.outputs.release_id != '' && steps.release.outputs.release_id != 'null'
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          RELEASE_ID: ${{ steps.release.outputs.release_id }}
        run: |
          # Check if an SBOM asset with this name already exists in the release
          ASSET_ID=$(curl -s -H "Authorization: token ${GITHUB_TOKEN}" \
            "https://api.github.com/repos/${GITHUB_REPOSITORY}/releases/${RELEASE_ID}/assets" \
            | jq -r ".[] | select(.name == \"sbom.spdx.json\") | .id")

          if [ -n "${ASSET_ID}" ] && [ "${ASSET_ID}" != "null" ]; then
            # Delete existing SBOM asset so we can re-upload the fresh scan
            curl -s -X DELETE -H "Authorization: token ${GITHUB_TOKEN}" \
              "https://api.github.com/repos/${GITHUB_REPOSITORY}/releases/assets/${ASSET_ID}" > /dev/null
            echo "Deleted existing sbom.spdx.json asset"
          fi

          # Upload the SBOM as a release asset
          curl -s -X POST -H "Authorization: token ${GITHUB_TOKEN}" \
            -H "Content-Type: application/spdx+json" \
            --data-binary @sbom.spdx.json \
            "https://uploads.github.com/repos/${GITHUB_REPOSITORY}/releases/${RELEASE_ID}/assets" > /dev/null
          echo "Uploaded sbom.spdx.json to release ${RELEASE_ID}"

      - name: Notify if no release found for tag
        if: steps.release.outputs.release_id == '' || steps.release.outputs.release_id == 'null'
        run: |
          echo "::notice::No GitHub Release found for tag ${GITHUB_REF#refs/tags/}. The SBOM was generated at ./sbom.spdx.json but was not attached to a release. Ensure the tag was created by the release-please process or manually create a release draft."