Multi-arch image support

hooks/README.md

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+The hooks in this directory are used to create multi-arch images using Docker Hub automated builds.
+
+Docker Hub hooks provide these predefined [environment variables](https://docs.docker.com/docker-hub/builds/advanced/#environment-variables-for-building-and-testing):
+
+* `SOURCE_BRANCH`: the name of the branch or the tag that is currently being tested.
+* `SOURCE_COMMIT`: the SHA1 hash of the commit being tested.
+* `COMMIT_MSG`: the message from the commit being tested and built.
+* `DOCKER_REPO`: the name of the Docker repository being built.
+* `DOCKERFILE_PATH`: the dockerfile currently being built.
+* `DOCKER_TAG`: the Docker repository tag being built.
+* `IMAGE_NAME`: the name and tag of the Docker repository being built. (This variable is a combination of `DOCKER_REPO:DOCKER_TAG`.)
+
+The current multi-arch image build relies on the original bitwarden_rs Dockerfiles, which use cross-compilation for architectures other than `amd64`, and don't yet support all arch/database/OS combinations. However, cross-compilation is much faster than QEMU-based builds (e.g., using `docker buildx`). This situation may need to be revisited at some point.
+
+## References
+
+* https://docs.docker.com/docker-hub/builds/advanced/
+* https://docs.docker.com/engine/reference/commandline/manifest/
+* https://www.docker.com/blog/multi-arch-build-and-images-the-simple-way/

hooks/arches.sh

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+# The default Debian-based SQLite images support these arches.
+#
+# Other images (Alpine-based, or with other database backends) currently
+# support only a subset of these.
+arches=(
+    amd64
+    arm32v6
+    arm32v7
+    arm64v8
+)
+
+case "${DOCKER_REPO}" in
+    *-mysql)
+        db=mysql
+        arches=(amd64)
+        ;;
+    *-postgresql)
+        db=postgresql
+        arches=(amd64)
+        ;;
+    *)
+        db=sqlite
+        ;;
+esac
+
+if [[ "${DOCKER_TAG}" == *alpine ]]; then
+    # The Alpine build currently only works for amd64.
+    os_suffix=.alpine
+    arches=(amd64)
+fi

hooks/build

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+#!/bin/bash
+
+echo ">>> Building images..."
+
+source ./hooks/arches.sh
+
+set -ex
+
+for arch in "${arches[@]}"; do
+    docker build \
+           -t "${DOCKER_REPO}:${DOCKER_TAG}-${arch}" \
+           -f docker/${arch}/${db}/Dockerfile${os_suffix} \
+           .
+done

hooks/push

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+#!/bin/bash
+
+echo ">>> Pushing images..."
+
+export DOCKER_CLI_EXPERIMENTAL=enabled
+
+declare -A annotations=(
+    [amd64]="--os linux --arch amd64"
+    [arm32v6]="--os linux --arch arm --variant v6"
+    [arm32v7]="--os linux --arch arm --variant v7"
+    [arm64v8]="--os linux --arch arm64 --variant v8"
+)
+
+source ./hooks/arches.sh
+
+set -ex
+
+declare -A images
+for arch in ${arches[@]}; do
+    images[$arch]="${DOCKER_REPO}:${DOCKER_TAG}-${arch}"
+done
+
+# Push the images that were just built; manifest list creation fails if the
+# images (manifests) referenced don't already exist in the Docker registry.
+for image in "${images[@]}"; do
+    docker push "${image}"
+done
+
+manifest_lists=("${DOCKER_REPO}:${DOCKER_TAG}")
+
+# If the Docker tag starts with a version number, assume the latest release is
+# being pushed. Add an extra manifest (`latest-release` or `alpine-release`,
+# as appropriate) to make it easier to track the latest release.
+if [[ "${DOCKER_TAG}" =~ ^[0-9]+\.[0-9]+\.[0-9]+ ]]; then
+    if [[ "${DOCKER_TAG}" == *alpine ]]; then
+        manifest_lists+=(${DOCKER_REPO}:alpine-release)
+    else
+        manifest_lists+=(${DOCKER_REPO}:latest-release)
+    fi
+fi
+
+for manifest_list in "${manifest_lists[@]}"; do
+    # Create the (multi-arch) manifest list of arch-specific images.
+    docker manifest create ${manifest_list} ${images[@]}
+
+    # Make sure each image manifest is annotated with the correct arch info.
+    # Docker does not auto-detect the arch of each cross-compiled image, so
+    # everything would appear as `linux/amd64` otherwise.
+    for arch in "${arches[@]}"; do
+        docker manifest annotate ${annotations[$arch]} ${manifest_list} ${images[$arch]}
+    done
+
+    # Push the manifest list.
+    docker manifest push --purge ${manifest_list}
+done