name: Build and Push

on:
  push:
    branches:
      - main

env:
  REGISTRY: git.mcintire.me
  IMAGE_NAME: graham/prop

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  build-and-push:
    name: Build and Push Docker Image
    runs-on: ubuntu-22.04

    # Runs a dockerd sidecar on the same bridge network as the job
    # container so the build doesn't depend on the host's docker socket
    # being mounted. Some act_runners don't mount it and there was no
    # way to tell at schedule time which runner would win — leading to
    # random "unable to connect to docker" failures that went away on a
    # re-run. With dind every runner has a daemon, every time.
    services:
      dockerd:
        image: docker:27-dind
        options: --privileged
        env:
          DOCKER_TLS_CERTDIR: ""

    env:
      DOCKER_HOST: tcp://dockerd:2375

    steps:
      - name: Checkout code
        uses: https://github.com/actions/checkout@v4

      - name: Install Docker CLI and buildx
        run: |
          # Dodge apt entirely — the runner image's bookworm repos have been
          # failing GPG verification with "At least one invalid signature".
          # The static Docker client binary talks to the dind sidecar via
          # the DOCKER_HOST env var set at the job level. buildx is needed
          # separately because the Dockerfile uses `--mount=type=cache`,
          # which is a BuildKit-only feature.
          curl -fsSL -o /tmp/docker.tgz \
            https://download.docker.com/linux/static/stable/x86_64/docker-27.5.1.tgz
          tar xzf /tmp/docker.tgz -C /tmp
          install -m 0755 /tmp/docker/docker /usr/local/bin/docker
          rm -rf /tmp/docker /tmp/docker.tgz

          mkdir -p /usr/libexec/docker/cli-plugins
          curl -fsSL -o /usr/libexec/docker/cli-plugins/docker-buildx \
            https://github.com/docker/buildx/releases/download/v0.19.3/buildx-v0.19.3.linux-amd64
          chmod +x /usr/libexec/docker/cli-plugins/docker-buildx

          docker --version
          docker buildx version

      - name: Wait for dockerd sidecar
        run: |
          # dind takes ~5-15s to finish booting inside the service
          # container; poll until the TCP endpoint answers.
          echo "Using DOCKER_HOST=${DOCKER_HOST}"

          for i in $(seq 1 60); do
            if docker info >/dev/null 2>&1; then
              echo "dockerd reachable after ${i}s"
              exit 0
            fi
            echo "Waiting for dockerd... ($i/60)"
            sleep 1
          done

          echo "dockerd never became reachable — diagnostics:" >&2
          echo "--- env | grep -i docker ---" >&2
          env | grep -i docker 2>&1 || true
          echo "--- docker info (verbose) ---" >&2
          docker info 2>&1 || true
          exit 1

      - name: Generate image tag
        id: tag
        run: |
          TIMESTAMP=$(date +%s)
          SHORT_SHA=$(git rev-parse --short=7 HEAD | cut -c1-7)
          TAG="main-${TIMESTAMP}-${SHORT_SHA}"
          echo "tag=${TAG}" >> $GITHUB_OUTPUT

      - name: Log in to container registry
        run: |
          # Exponential backoff (2s, 4s, 8s) around docker login to
          # ride out transient registry blips without failing the
          # whole workflow.
          attempt=1
          max_attempts=3
          while : ; do
            if echo "${{ secrets.REGISTRY_PASSWORD }}" | \
                docker login "${{ secrets.REGISTRY_URL }}" \
                  -u "${{ secrets.REGISTRY_USER }}" \
                  --password-stdin; then
              exit 0
            fi
            if [ "$attempt" -ge "$max_attempts" ]; then
              echo "docker login failed after $attempt attempts" >&2
              exit 1
            fi
            delay=$((2 ** attempt))
            echo "docker login attempt $attempt failed; retrying in ${delay}s"
            sleep "$delay"
            attempt=$((attempt + 1))
          done

      - name: Build and push Docker image
        run: |
          IMAGE="${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}"
          TAG="${{ steps.tag.outputs.tag }}"
          BUILD_TIMESTAMP=$(date -u +"%Y-%m-%dT%H:%M:%SZ")

          attempt=1
          max_attempts=3
          while : ; do
            if docker buildx build \
                --build-arg BUILD_TIMESTAMP="${BUILD_TIMESTAMP}" \
                -t "${IMAGE}:${TAG}" -t "${IMAGE}:latest" \
                --push \
                .; then
              exit 0
            fi
            if [ "$attempt" -ge "$max_attempts" ]; then
              echo "docker buildx build failed after $attempt attempts" >&2
              exit 1
            fi
            delay=$((2 ** attempt))
            echo "docker buildx build attempt $attempt failed; retrying in ${delay}s"
            sleep "$delay"
            attempt=$((attempt + 1))
          done