Calico go-build

Base image for doing golang builds for the various project calico builds.

Building the image

To build the image:

make build

The above will build for whatever architecture you are running on. To force a different architecture:

ARCH=<somearch> make build

Tagging

The image is tagged the version, e.g. v0.9 or latest. In addition, the given architecture is appended to the end. Thus, for example, the latest version on amd64 will be calico/go-build:latest-amd64.

The above tagging scheme keeps everything in a single image repository calico/go-build and prepares for using milti-architecture image manifests.

As of this writing, the only way to create such manifests is using the manifest-tool, which involves multiple steps. This can be incorporated into the build process, or we can wait until docker manifest is rolled into the docker CLI, see this PR.

Until such time as the docker manifest is ready, or we decide to use manifest-tool, the default image name will point to amd64. Thus, calico/go-build:latest refers to calico/go-build:latest-amd64.

Cross building using go-build:

Any supported platform can be built natively from its own platform, i.e.g amd64 from amd64, arm64 from arm64 and ppc64le from ppc64le. In addition, ppc64le and arm64 are supported for cross-building from amd64 only. We do not (yet) support cross-building from arm64 and ppc64le.

The cross-build itself will function normally on any platform, since golang supports cross-compiling using GOARCH=<target> go build .

docker run -e GOARCH=<somearch> calico/go-build:latest-amd64 sh -c 'go build hello.go || ./hello'

The above will output a binary hello built for the architecture <somearch>.

Running a Binary

To run a binary from a different architecture, you need to use binfmt and qemu static.

Register qemu-*-static for all supported processors except the current one using the following command:

docker run --rm --privileged multiarch/qemu-user-static:register

If a cross built binary is executed in the go-build container qemu-static will automatically be used.

Testing Cross-Run

There is a Makefile target that cross-builds and runs a binary. To run it on your own architecture:

make testcompile

or

make testcompile ARCH=$(uname -m)

To test on a different architecture, for example arm64 when you are running on amd64, pass it an alternate architecture:

make testcompile ARCH=arm64

You should see the "success" message.