Multi-platform Docker images

On GoReleaser there are two main ways of doing that: the easier one is to use the ko integration.

If you don't want to, or can't, use Ko for whatever reason, this guide is for you!

Creating Multi-platform docker images with GoReleaser

GoReleaser splits the build and publish phase, which makes its usage less obvious.

First, you need to define one dockers item for each platform you want to build. Usually, you would tag it like myorg/myimage:version-platform. It is also important to use buildx. Here's an example:

# .goreleaser.yaml
dockers:
- image_templates:
  - 'myorg/myuser:{{ .Tag }}-amd64'
  use: buildx
  build_flag_templates:
  - "--pull"
  - "--platform=linux/amd64"
- image_templates:
  - 'myorg/myuser:{{ .Tag }}-arm64'
  use: buildx
  build_flag_templates:
  - "--pull"
  - "--platform=linux/arm64"
  goarch: arm64

This will, on build time, create two Docker images (myorg/myuser:v1.2.3-amd64 and myorg/myuser:v1.2.3-arm64).

Now, if we want to make them both available as a single image (myorg/myuser:v1.2.3), we'll need to add a manifest configuration that will publish them behind that single name. Here's how it would look like:

# .goreleaser.yaml
docker_manifests:
- name_template: 'myorg/myuser:{{ .Tag }}'
  image_templates:
  - 'myorg/myuser:{{ .Tag }}-amd64'
  - 'myorg/myuser:{{ .Tag }}-arm64'

And that is it!

Other things to pay attention to

For buildx to work properly, you'll need to install qemu. On GitHub actions, the easiest way is to use docker/setup-qemu-action.

It's also important that the FROM in your Dockerfile is multi-platform, otherwise it'll not work.

As long as you have Qemu and Docker set up, everything should just work.