build-sboms.yml

name: Build & Sign SBOMs

# Push a plain version tag (e.g. "4.2.3") to trigger a build. The tag itself
# is the OOD version to build — there's no separate input to keep in sync.
on:
  push:
    tags:
      - "*.*.*"

env:
  # Pins the syft version used by every job. Bump when a new syft release
  # is worth picking up — see https://github.com/anchore/syft/releases
  SYFT_VERSION: v1.48.0

jobs:
  build:
    name: ${{ matrix.distro }} / ${{ matrix.arch }}
    runs-on: ${{ matrix.runner }}
    permissions:
      contents: read
      id-token: write # required for cosign keyless (Fulcio) signing
    strategy:
      fail-fast: false
      matrix:
        distro: [amzn2023, el8, el9, el10, noble, resolute, bookworm, trixie]
        arch: [x86_64, aarch64]
        include:
          - arch: x86_64
            runner: ubuntu-24.04
          - arch: aarch64
            runner: ubuntu-24.04-arm
        # ppc64le is intentionally not covered here — no GitHub-hosted
        # runner exists for it. See issue #1 for the self-hosted /
        # IBM-managed-runner path being explored separately.
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Derive OOD version from tag
        id: version
        run: |
          VERSION="${GITHUB_REF_NAME}"
          if ! [[ "$VERSION" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
            echo "::error::Tag '$VERSION' isn't a plain semver OOD version (e.g. 4.2.3) — refusing to build."
            exit 1
          fi
          echo "version=$VERSION" >> "$GITHUB_OUTPUT"
          echo "major_minor=${VERSION%.*}" >> "$GITHUB_OUTPUT"

      - name: Install syft
        run: ./scripts/install-syft.sh

      - name: Install cosign
        uses: sigstore/cosign-installer@v3

      - name: Build & scan ${{ matrix.distro }}/${{ matrix.arch }}
        env:
          ARCH: ${{ matrix.arch }}
          USE_COSIGN: "1"
          COSIGN_MODE: keyless
        run: ./scripts/scan-all.sh "${{ steps.version.outputs.version }}" "${{ matrix.distro }}"

      - name: Upload SBOM artifact
        uses: actions/upload-artifact@v4
        with:
          name: sbom-${{ matrix.distro }}-${{ matrix.arch }}
          path: ${{ steps.version.outputs.major_minor }}/**/*
          if-no-files-found: error
          retention-days: 7

  publish:
    name: Open PR with generated SBOMs
    needs: build
    # Run with whatever succeeded, even if some distro/arch legs failed --
    # OSC's staging repo doesn't always have every arch built for every
    # distro at the same time (amzn2023/el10 lag on aarch64 as of 4.2.4).
    # Only skip if the whole run was cancelled outright.
    if: ${{ !cancelled() }}
    runs-on: ubuntu-24.04
    permissions:
      contents: write
      pull-requests: write
      id-token: write # required for cosign keyless signing of checksums.txt
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Derive OOD version from tag
        id: version
        run: |
          VERSION="${GITHUB_REF_NAME}"
          echo "version=$VERSION" >> "$GITHUB_OUTPUT"
          echo "major_minor=${VERSION%.*}" >> "$GITHUB_OUTPUT"

      - name: Download all SBOM artifacts
        uses: actions/download-artifact@v4
        with:
          pattern: sbom-*
          path: _artifacts
          merge-multiple: true
          # If every leg failed there's nothing to publish -- fail here
          # rather than continue on to an empty/no-op PR.
          if-no-artifact-found: error

      - name: Merge into the repo tree
        run: |
          # upload-artifact strips everything before the first wildcard in
          # the upload path (4.2/**/* -> artifacts rooted at <distro>/<arch>/),
          # so the major.minor prefix has to be put back here.
          MM="${{ steps.version.outputs.major_minor }}"
          mkdir -p "$MM"
          cp -a _artifacts/. "$MM/"
          rm -rf _artifacts

      - name: Install cosign
        uses: sigstore/cosign-installer@v3

      - name: Rebuild & sign checksums.txt
        env:
          USE_COSIGN: "1"
          COSIGN_MODE: keyless
        run: ./scripts/build-checksums.sh "${{ steps.version.outputs.major_minor }}"

      - name: Open PR
        uses: peter-evans/create-pull-request@v6
        with:
          # Required: this workflow is only ever triggered by a tag push,
          # which leaves the checkout in a detached-HEAD state (same as
          # `release` events). Without an explicit base, the action can't
          # figure out what branch to open the PR against.
          base: main
          commit-message: "sboms: add ${{ steps.version.outputs.version }} (x86_64 + aarch64, all distros)"
          branch: "sbom/${{ steps.version.outputs.version }}"
          title: "SBOMs for OOD ${{ steps.version.outputs.version }}"
          body: |
            Auto-generated by the `Build & Sign SBOMs` workflow for tag
            `${{ steps.version.outputs.version }}`.

            Covers `x86_64` and `aarch64` for every distro that had a
            successful build in this run. If a distro/arch combo you'd
            expect isn't here, check this run's job list for a red leg —
            OSC's staging repo doesn't always have every arch built for
            every distro at the same time (see #1 / the aarch64-lag issue
            for known gaps). Re-tag once the missing build lands upstream
            to backfill it.

            `checksums.txt` and each individual SBOM are signed keylessly
            via cosign/Fulcio — verify with:

            ```
            cosign verify-blob --certificate <file>.pem --signature <file>.sig \
              --certificate-identity-regexp '.*' \
              --certificate-oidc-issuer https://token.actions.githubusercontent.com \
              <file>
            ```
          add-paths: "${{ steps.version.outputs.major_minor }}/**"