Setting up docker buildx on Linux

Table of Contents

Docker buildx on Linux #

Installation instructions for Ubuntu

To execute docker commands without sudo. We need to add the username to the docker group.

Find the current username by typing who
Add username to docker group
Reboot system

$ who
vikaspogu :0           2020-12-05 10:10 (:0)
$ sudo usermod -aG docker vikaspogu
$ sudo reboot

Enable buildx #

Create a new config.json file under the ~.docker folder and enable the experimental feature

$ mkdir ~/.docker
$ vim ~/.docker/config.json
{
 "experimental": "enabled"
}

Now you should be able to do multi-arch builds

docker buildx build -t vikaspogu/test:v0.0.1 . --push --platform linux/arm64

If you encounter the below error when trying to build the image using buildx. It would help if you created new build instance

failed to solve: rpc error: code = Unknown desc = failed to solve with frontend dockerfile.v0: failed to load LLB: runtime execution on platform linux/arm64 not supported

Create build instance #

Follow the below steps to create a new build instance for arm64.

List existing buildx platforms
Create a new build instance named arm64
Inspect build instance to verify arm64 platform exists
Set builder instance
Build multi-platform image

$ docker buildx ls
NAME/NODE DRIVER/ENDPOINT             STATUS   PLATFORMS
default   docker                               
  default default                     running  linux/amd64, linux/386

# create the builder
$ docker buildx create  --name amr64 --platform linux/amd64,linux/arm64

# start the buildx
$ docker buildx inspect arm64 --bootstrap
Name:   arm64
Driver: docker-container

Nodes:
Name:      arm640
Endpoint:  unix:///var/run/docker.sock
Status:    running
Platforms: linux/amd64*, linux/arm64*, linux/riscv64, linux/ppc64le, linux/386, linux/arm/v7, linux/arm/v6, linux/s390x

# set current builder instance
$ docker buildx use amr64

# build the multi images
$ docker buildx build -t vikaspogu/test:v0.0.1 . --push --platform linux/arm64

If you encounter /bin/sh: Invalid ELF image for this architecture error. Run the following docker image and then build

docker run --rm --privileged multiarch/qemu-user-static --reset -p yes