This is a short post on how to create container images with docker and buildx so that it’s compatible with ARM architectures such as the Apple M1 and Raspberry Pi 64 bit.
We will have a simple dockerfile that runs from a alpine image and we will be installing curl:
FROM alpine:latest LABEL maintainer "Ruan Bekker" RUN apk --no-cache add curl
List your current builder instances:
$ docker buildx ls NAME/NODE DRIVER/ENDPOINT STATUS PLATFORMS default docker default running linux/amd64, linux/386
As you can see we only have amd64 and i386 architecture support for when we build container images.
Create a build instance that supports arm64 and arm:
$ docker buildx create --name multi-arch \ --platform "linux/arm64,linux/amd64,linux/arm/v7" \ --driver "docker-container"
Now we can update our default builder instance:
$ docker buildx use multi-arch
Build and Push
If you want to push to your image registry (using an assumption its docker hub):
$ docker login
Now we can build and push our container image with multi-arch support to our image registry:
$ docker buildx build \ --platform "linux/amd64,linux/arm64,linux/arm/v7" \ --tag ruanbekker/curl:test \ --push .
When you head over to my dockerhub repository:
You will see the digests for each architecture that we included:
Test on Apple M1
If we test this by running a container from our container image on a Apple M1, we will see that it will use the correct digest hash:
$ docker run -it ruanbekker/curl:test sh Unable to find image 'ruanbekker/curl:test' locally test: Pulling from ruanbekker/curl 9b18e9b68314: Already exists 5f2095374d74: Pull complete Digest: sha256:5d87f95ded0e7e057152f8c32d4b0b81a1e2415f2b6a2ec2ac53dd8cbbc4ab39 Status: Downloaded newer image for ruanbekker/curl:test / # curl curl: try 'curl --help' or 'curl --manual' for more information
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