name: Build and Push Multi-Arch Image
description: Log in to a container registry, set up a remote Docker Buildx builder over SSH, and build + push a multi-arch image.

inputs:
  registry_host:
    description: Hostname of the container registry
    required: true
    default: git.ivanch.me
  registry_username:
    description: Username for the container registry
    required: true
    default: ivanch
  registry_password:
    description: Password / token for the container registry (pass via secrets)
    required: true
  image:
    description: Full image reference (host/path/name) without tag — :latest is appended
    required: true
  platforms:
    description: Comma-separated list of target platforms
    required: false
    default: linux/amd64,linux/arm64
  build_context:
    description: Docker build context path
    required: false
    default: .
  build_dockerfile:
    description: Path to the Dockerfile (relative to context)
    required: false
    default: Dockerfile
  ssh_key:
    description: SSH private key for the remote Docker builder host (pass via secrets)
    required: true
  docker_host:
    description: Hostname of the remote Docker Buildx builder
    required: false
    default: docker-build.haven
  docker_user:
    description: SSH user for the remote Docker builder
    required: false
    default: root

runs:
  using: composite
  steps:
    - name: Log in to Container Registry
      shell: bash
      env:
        REGISTRY_HOST: ${{ inputs.registry_host }}
        REGISTRY_USERNAME: ${{ inputs.registry_username }}
        REGISTRY_PASSWORD: ${{ inputs.registry_password }}
      run: |
        echo "${REGISTRY_PASSWORD}" \
          | docker login "${REGISTRY_HOST}" \
              -u "${REGISTRY_USERNAME}" \
              --password-stdin

    - name: Set up SSH key for remote builder
      shell: bash
      env:
        SSH_KEY: ${{ inputs.ssh_key }}
        DOCKER_HOST: ${{ inputs.docker_host }}
      run: |
        mkdir -p ~/.ssh
        echo "${SSH_KEY}" > ~/.ssh/id_ed25519
        chmod 600 ~/.ssh/id_ed25519
        ssh-keyscan "${DOCKER_HOST}" >> ~/.ssh/known_hosts

    - name: Set up remote Docker Buildx builder
      shell: bash
      env:
        DOCKER_HOST: ${{ inputs.docker_host }}
        DOCKER_USER: ${{ inputs.docker_user }}
      run: |
        docker context create remote-builder \
          --docker "host=ssh://${DOCKER_USER}@${DOCKER_HOST}"
        docker context use remote-builder
        docker buildx inspect --bootstrap

    - name: Build and Push Multi-Arch Image
      uses: docker/build-push-action@v6
      with:
        push: true
        context: ${{ inputs.build_context }}
        file: ${{ inputs.build_dockerfile }}
        builder: remote-builder
        platforms: ${{ inputs.platforms }}
        tags: |
          ${{ inputs.image }}:latest