multiarch-docker-build.sh

# multiarch-docker-build
# Usage:
#   multiarch-docker-build [options] <registry/image> [extra-tag]
#
# Options:
#   --builder <name>      buildx builder name (default: multiarch-builder)
#   --platforms <list>    target platforms (default: linux/amd64,linux/arm64)
#   --dockerfile <path>   Dockerfile path (default: Dockerfile)
#   --context <path>      build context (default: .)
#   --push                push multi-arch (default)
#   --load                load single-arch locally
#   --github-pat <token>  forward a GitHub PAT as build arg
#   --ssh                 enable SSH tunneling (uses default or provided key)
#   --ssh-key <path>      path to private key (default: ~/.ssh/id_ed25519_github)

multiarch-docker-build () {
  local builder="multiarch-builder"
  local plats="linux/amd64,linux/arm64"
  local df="Dockerfile"
  local ctx="."
  local push=1
  local ssh=0
  local ssh_key="$HOME/.ssh/id_ed25519_github"
  local pat=""

  while [[ $# -gt 0 ]]; do
    case "$1" in
      --builder) builder="$2"; shift 2 ;;
      --platforms) plats="$2"; shift 2 ;;
      --dockerfile) df="$2"; shift 2 ;;
      --context) ctx="$2"; shift 2 ;;
      --push) push=1; shift ;;
      --load) push=0; shift ;;
      --github-pat) pat="$2"; shift 2 ;;
      --ssh) ssh=1; shift ;;
      --ssh-key) ssh_key="$2"; shift 2 ;;
      -h|--help)
        echo "Usage: multiarch-docker-build [options] <registry/image> [extra-tag]"
        return 0 ;;
      *) break ;;
    esac
  done

  local img="${1:-}"; shift || true
  local extra="${1:-}"
  [[ -z "$img" ]] && { echo "Error: image name required"; return 1; }

  local stamp="$(date +%Y%m%d-%H%M)"

  if ! docker buildx ls | grep -q "^${builder}\b"; then
    docker buildx create --name "$builder" --use
  else
    docker buildx use "$builder"
  fi
  docker buildx inspect --bootstrap >/dev/null 2>&1

  local args=(docker buildx build --platform "$plats" -f "$df"
    -t "$img:latest" -t "$img:$stamp")
  [[ -n "$extra" ]] && args+=(-t "$img:$extra")
  [[ -n "$pat" ]] && args+=(--build-arg "GITHUB_PAT=$pat")

  if [[ "$ssh" -eq 1 ]]; then
    if [[ -z "${SSH_AUTH_SOCK:-}" ]]; then eval "$(ssh-agent -s)" >/dev/null; fi
    [[ -r "$ssh_key" ]] && ssh-add "$ssh_key" >/dev/null 2>&1 || true
    args+=(--ssh default)
  fi

  args+=("$ctx")
  [[ "$push" -eq 1 ]] && args+=(--push) || args+=(--load)

  DOCKER_BUILDKIT=1 "${args[@]}"
}