build.yml

---
name: Build container image
on:
  pull_request:
    branches:
      - main
    paths-ignore:
      - 'README.md'
      - 'docs/**'
  schedule:
    - cron: '00 05 * * 0'  # 5:00am UTC Sunday; about 1:00am Eastern during daylight time
  push:
    branches:
      - main
    paths-ignore:
      - '**/README.md'
      - 'docs/**'
  workflow_dispatch:

env:
  IMAGE_NAME: "${{ github.event.repository.name }}"  # output image name, usually same as repo name
  IMAGE_REGISTRY: "ghcr.io/${{ github.repository_owner }}"  # do not edit
  DEFAULT_TAG: "latest"

concurrency:
  group: ${{ github.workflow }}-${{ github.ref || github.run_id }}
  cancel-in-progress: ${{ github.event_name == 'pull_request' }}

jobs:
  build_push:
    name: Build and push image
    runs-on: ubuntu-24.04
    timeout-minutes: 90

    permissions:
      contents: read
      packages: write

    steps:
      - name: Prepare environment
        run: |
          # Lowercase the image uri
          echo "IMAGE_REGISTRY=${IMAGE_REGISTRY,,}" >> ${GITHUB_ENV}
          echo "IMAGE_NAME=${IMAGE_NAME,,}" >> ${GITHUB_ENV}

      # These stage versions are pinned by https://github.com/renovatebot/renovate
      - name: Checkout
        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0

      # This is optional, but if you see that your builds are way too big for the runners, you can enable this by uncommenting the following lines:
      - name: Maximize build space
        uses: ublue-os/remove-unwanted-software@695eb75bc387dbcd9685a8e72d23439d8686cba6

      # Ubuntu 24.04's Podman does not preserve Chunkah's layer annotations
      # when pushing. Use the same newer toolchain as Aurora until the hosted
      # runner includes a sufficiently new Podman release. The step skips
      # itself once the runner's podman major version is >= 5, so it retires
      # automatically when GitHub updates the hosted image.
      - name: Update Podman
        run: |
          set -eux
          need_major=5
          have_major=$(podman --version | grep -oE '[0-9]+' | head -n 1)
          if [ "${have_major}" -ge "${need_major}" ]; then
            echo "Runner podman is already >= ${need_major}; skipping cross-release install"
            exit 0
          fi
          echo "deb http://azure.archive.ubuntu.com/ubuntu resolute universe main" | sudo tee /etc/apt/sources.list.d/resolute.list
          sudo apt-get update
          sudo apt-get install -y --allow-downgrades \
            crun/resolute \
            buildah/resolute \
            podman/resolute \
            skopeo/resolute
          podman --version

      # GitHub-hosted runners keep most of their free space on /mnt (~66G),
      # while / has far less headroom. Building the image and then re-layering
      # it with Chunkah keeps two copies of the root filesystem in podman's
      # storage at once, which can exhaust /. Relocate podman's rootless
      # storage onto /mnt so the rechunk has room. The image-copy temp dir is
      # deliberately left on / (freed by relocating storage) so the two large
      # consumers land on separate disks instead of competing for one.
      - name: Move container storage to the large runner disk
        run: |
          set -eux
          sudo mkdir -p /mnt/containers
          sudo chown "$(id -u):$(id -g)" /mnt/containers
          mkdir -p "${HOME}/.local/share"
          rm -rf "${HOME}/.local/share/containers"
          ln -s /mnt/containers "${HOME}/.local/share/containers"
          df -h / /mnt

      - name: Get current date
        id: date
        run: |
          echo "date=$(date -u +%Y\-%m\-%d\T%H\:%M\:%S\Z)" >> $GITHUB_OUTPUT

      - name: Image Metadata
        uses: docker/metadata-action@80c7e94dd9b9319bd5eb7a0e0fe9291e23a2a2e9 # v6.1.0
        id: metadata
        with:
          # This generates all the tags for your image, you can add custom tags here too!
          # Default tags are "$DEFAULT_TAG" and "$DEFAULT_TAG.$date".
          tags: |
            type=raw,value=${{ env.DEFAULT_TAG }}
            type=raw,value=${{ env.DEFAULT_TAG }}.{{date 'YYYYMMDD'}}
            type=raw,value={{date 'YYYYMMDD'}}
            type=sha,enable=${{ github.event_name == 'pull_request' }}
            type=ref,event=pr
          labels: |
            org.opencontainers.image.created=${{ steps.date.outputs.date }}
            org.opencontainers.image.description=Aurora DX image with ZFS support
            org.opencontainers.image.documentation=https://raw.githubusercontent.com/${{ github.repository_owner }}/${{ env.IMAGE_NAME }}/${{ github.sha }}/README.md
            org.opencontainers.image.source=https://github.com/${{ github.repository_owner }}/${{ env.IMAGE_NAME }}/blob/${{ github.sha }}/Containerfile
            org.opencontainers.image.title=${{ env.IMAGE_NAME }}
            org.opencontainers.image.url=https://github.com/${{ github.repository_owner }}/${{ env.IMAGE_NAME }}/tree/${{ github.sha }}
            org.opencontainers.image.vendor=${{ github.repository_owner }}
            org.opencontainers.image.version=${{ env.DEFAULT_TAG }}.{{date 'YYYYMMDD'}}
            containers.bootc=1
          sep-tags: " "
          sep-annotations: " "

      - name: Build Image
        id: build_image
        uses: redhat-actions/buildah-build@7a95fa7ee0f02d552a32753e7414641a04307056 # v2
        with:
          containerfiles: |
            ./Containerfile
          # Postfix image name with -custom to make it a little more descriptive
          # Syntax: https://docs.github.com/en/actions/learn-github-actions/expressions#format
          image: ${{ env.IMAGE_NAME }}
          tags: ${{ steps.metadata.outputs.tags }}
          labels: ${{ steps.metadata.outputs.labels }}
          oci: false

      # Post-process the completed image so the ZFS and replacement-kernel
      # content is chunked along with the inherited Aurora filesystem.
      #
      # Chunkah's output used to be piped straight into `podman load`, which
      # forced the source image and the re-layered copy to coexist in one
      # container storage (~2x the unpacked image) and exhausted the runner
      # disk intermittently. Instead, buffer the compressed archive to a file
      # on / , delete the source image to free its layers, and only then load
      # the archive with its unpack temp dir pointed at /mnt. Neither disk
      # ever has to hold two unpacked copies of the image at once.
      - name: Rechunk Image with Chunkah
        env:
          CHUNKAH_IMAGE: quay.io/coreos/chunkah:v0.6.0
        run: |
          set -euo pipefail

          source_image="localhost/${IMAGE_NAME}:${DEFAULT_TAG}"
          chunked_image="localhost/${IMAGE_NAME}:chunkah"
          archive=/tmp/chunkah-oci.tar
          export CHUNKAH_CONFIG_STR
          CHUNKAH_CONFIG_STR="$(podman inspect "${source_image}")"

          echo "==> Disk usage before rechunk" && df -h / /mnt

          podman run --rm \
            --mount=type=image,src="${source_image}",target=/chunkah \
            -e CHUNKAH_CONFIG_STR \
            "${CHUNKAH_IMAGE}" build \
              --verbose \
              --compressed \
              --max-layers 128 \
              --prune /sysroot/ \
              --label ostree.commit- \
              --label ostree.final-diffid- \
              --tag "${chunked_image}" > "${archive}"

          # The archive is self-contained, so nothing left in container
          # storage is needed anymore: not the source image, not the Aurora
          # base or akmods images (tagged, so a plain prune would keep
          # them), not the Chunkah image. Remove them all so the load starts
          # against an empty store.
          podman image prune -af
          echo "==> Disk usage after pruning container storage" && df -h / /mnt

          # podman unpacks oci archives into TMPDIR before applying them;
          # keep that on /mnt next to container storage instead of /var/tmp.
          # /mnt is root-owned on the hosted runners, hence sudo + chown.
          sudo mkdir -p /mnt/tmp
          sudo chown "$(id -u):$(id -g)" /mnt/tmp
          TMPDIR=/mnt/tmp podman load -i "${archive}"
          rm -f "${archive}"
          echo "==> Disk usage after load" && df -h / /mnt

          for tag in ${{ steps.metadata.outputs.tags }}; do
            podman tag "${chunked_image}" "${IMAGE_NAME}:${tag}"
          done

      # These `if` statements are so that pull requests for your custom images do not make it publish any packages under your name without you knowing
      # They also check if the runner is on the default branch so that things like the merge queue (if you enable it), are going to work
      - name: Login to GitHub Container Registry
        uses: docker/login-action@650006c6eb7dba73a995cc03b0b2d7f5ca915bee # v4.2.0
        if: github.event_name != 'pull_request' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Push To GHCR
        uses: redhat-actions/push-to-registry@5ed88d269cf581ea9ef6dd6806d01562096bee9c # v2
        if: github.event_name != 'pull_request' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
        id: push
        env:
          REGISTRY_USER: ${{ github.actor }}
          REGISTRY_PASSWORD: ${{ github.token }}
        with:
          registry: ${{ env.IMAGE_REGISTRY }}
          image: ${{ env.IMAGE_NAME }}
          # Push exactly one tag. The remaining tags are copied from the
          # pushed digest in the next step so every tag is byte-identical.
          tags: ${{ env.DEFAULT_TAG }}
          username: ${{ env.REGISTRY_USER }}
          password: ${{ env.REGISTRY_PASSWORD }}

      # podman can emit different manifest bytes for sequential pushes of
      # the same local image: the first push compresses and uploads, later
      # pushes reuse cached blob info, and the resulting manifests can carry
      # different digests. That split what `latest` and the date tags pointed
      # at and left `latest` outside the signed digest. Copy the single
      # pushed manifest to the remaining tags server-side instead;
      # --preserve-digests makes skopeo fail rather than rewrite the
      # manifest, so every tag is identical by construction.
      - name: Propagate tags from the pushed digest
        if: github.event_name != 'pull_request' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
        run: |
          set -euo pipefail
          digest="${{ steps.push.outputs.digest }}"
          if [ -z "${digest}" ]; then
            echo "push step did not expose a digest" >&2
            exit 1
          fi
          for tag in ${{ steps.metadata.outputs.tags }}; do
            if [ "${tag}" = "${DEFAULT_TAG}" ]; then
              continue
            fi
            skopeo copy --preserve-digests \
              "docker://${IMAGE_REGISTRY}/${IMAGE_NAME}@${digest}" \
              "docker://${IMAGE_REGISTRY}/${IMAGE_NAME}:${tag}"
          done

      # All tags in this job point at one manifest pushed from one local
      # image. Enforce that as an invariant instead of trusting it: if any
      # published tag resolves to a different digest than the one about to
      # be signed, fail before signing rather than publish a half-signed
      # tag set.
      - name: Verify pushed tags share one digest
        if: github.event_name != 'pull_request' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
        run: |
          set -euo pipefail
          expected="${{ steps.push.outputs.digest }}"
          if [ -z "${expected}" ]; then
            echo "push step did not expose a digest" >&2
            exit 1
          fi
          for tag in ${{ steps.metadata.outputs.tags }}; do
            actual=$(skopeo inspect --format '{{.Digest}}' "docker://${IMAGE_REGISTRY}/${IMAGE_NAME}:${tag}")
            if [ "${actual}" != "${expected}" ]; then
              echo "Tag ${tag} resolves to ${actual}, expected ${expected}" >&2
              exit 1
            fi
            echo "Tag ${tag} -> ${actual} OK"
          done

      # This section is optional and only needs to be enabled if you plan on distributing
      # your project for others to consume. You will need to create a public and private key
      # using Cosign and save the private key as a repository secret in Github for this workflow
      # to consume. For more details, review the image signing section of the README.
      - name: Install Cosign
        uses: sigstore/cosign-installer@6f9f17788090df1f26f669e9d70d6ae9567deba6 # v4.1.2
        if: github.event_name != 'pull_request' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
        with:
          cosign-release: 'v2.6.1'

      - name: Sign container image
        if: github.event_name != 'pull_request' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
        run: |
          cosign sign -y --key env://COSIGN_PRIVATE_KEY \
            "${{ env.IMAGE_REGISTRY }}/${{ env.IMAGE_NAME }}@${{ steps.push.outputs.digest }}"
        env:
          COSIGN_EXPERIMENTAL: false
          COSIGN_PRIVATE_KEY: ${{ secrets.SIGNING_SECRET }}