Create a multi-arch docker image from arch tags

make-multiarch.bash

#!/bin/bash
set -eo pipefail

pull_image() {
    if ! docker inspect $1 ; then
        docker pull $1
    fi
    docker inspect $1
}

IMAGE=$1
if [ -z "$IMAGE" ]; then
  echo "set image as argument"
  exit 1
fi
ARCH_TAGS=(\
           arm \
           arm64 \
           amd64 \
)
ARCH_IMAGES=("${ARCH_TAGS[@]/#/${IMAGE}:}")

echo "Inspecting / fetching images for ${IMAGE}..."
for aarch in "${ARCH_TAGS[@]}"; do
    echo "Getting tag ${aarch}..."
    pull_image ${IMAGE}:${aarch}
done

TARGET=${IMAGE}:latest
echo "Creating manifest ${TARGET}..."
docker manifest create --amend $TARGET ${ARCH_IMAGES[@]}
docker manifest push --purge ${TARGET}