CODEWITHSUNDEEP
dockerbuildx
swch
swch

Reputation: 1556

Difference between docker buildx build and docker build for multi arch images

I have problem with understanding the difference between docker build vs docker buildx build commands in context of building multi arch images.

In docker documentation I see that docker build is alias for docker buildx build: https://docs.docker.com/reference/cli/docker/buildx/build/ So I assume there should be no differences between them.

I am on M1 Macbook and want to build multi arch image and push it to registry. So I've created new builder with docker-container driver:

docker buildx create \
  --name multi-platform-builder \
  --driver docker-container \
  --use

With docker buildx ls I can see that new builder is the default one:

% docker buildx ls
NAME/NODE                     DRIVER/ENDPOINT                   STATUS    BUILDKIT   PLATFORMS
multi-platform-builder*       docker-container                                       
 \_ multi-platform-builder0    \_ unix:///var/run/docker.sock   running   v0.15.2    linux/arm64, linux/amd64, linux/amd64/v2, linux/riscv64, linux/ppc64le, linux/s390x, linux/386, linux/mips64le, linux/mips64, linux/arm/v7, linux/arm/v6
default                       docker                                                 
 \_ default                    \_ default                       running   v0.13.2    linux/arm64, linux/amd64, linux/amd64/v2, linux/riscv64, linux/ppc64le, linux/s390x, linux/386, linux/mips64le, linux/mips64, linux/arm/v7, linux/arm/v6
desktop-linux                 docker                                                 
 \_ desktop-linux              \_ desktop-linux                 running   v0.13.2    linux/arm64, linux/amd64, linux/amd64/v2, linux/riscv64, linux/ppc64le, linux/s390x, linux/386, linux/mips64le, linux/mips64, linux/arm/v7, linux/arm/v6

Now the questions.

  1. If the docker build is an alias for docker buildx build, why this command does not work:
docker build \
--platform=linux/arm64,linux/amd64 \
-t myrepo/myapp:1.0.0 \
-t myrepo/myapp:latest \
--push \
.

and fail with message ERROR: Multi-platform build is not supported for the docker driver. but buildx build version works ok:

docker buildx build \
--platform=linux/arm64,linux/amd64 \
-t myrepo/myapp:1.0.0 \
-t myrepo/myapp:latest \
--push \
.

My Docker Desktop version is 4.30.0 with Docker Engine 26.1.1

Upvotes: 9

Views: 8635

Answers (1)

AxB
AxB

Reputation: 705

You are correct that docker build is an alias of docker buildx build. However docker build uses the default buildx builder which has docker set a driver and docker driver doesn't support features like Multi-arch images.

To use custom builder with docker build command add a --builder option with the name of your custom builder. So in your case command would look like this.

docker build \
--platform=linux/arm64,linux/amd64 \
-t myrepo/myapp:1.0.0 \
-t myrepo/myapp:latest \
--push \
--builder multi-platform-builder \
.

Upvotes: 11

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