nextcloud-docs/golang

What is Go?

Go, also called golang, is a programming language initially developed at Google in 2007 by Robert Griesemer, Rob Pike, and Ken Thompson. It is a statically-typed language with syntax loosely derived from that of C, adding garbage collection, type safety, some dynamic-typing capabilities, additional built-in types such as variable-length arrays and key-value maps, and a large standard library.

wikipedia.org/wiki/Go_(programming_language)

How to use this image

Start a go instance running in your app.

For this image, the most straight-forward use is to use a golang container as both the build environment as well as the runtime environment. In your Dockerfile, you can do something along the lines of the following will compile and run your project.

FROM golang:1.3-onbuild
CMD ["./myapp"]

This image includes multiple ONBUILD triggers so that should be all that you need for most applications. The build will COPY . /usr/src/app, RUN go get -d -v, and RUN go build -v.

Then run and build the docker image.

docker build -t my-golang-app
docker run -it --rm --name my-running-app my-golang-app

Compile your app inside the docker container.

It is not always appropriate to run your app inside a container. In instances where you only want to compile inside the docker instance, you can do something along the lines of the following.

docker run --rm -v "$(pwd)":/usr/src/myapp -w /usr/src/myapp golang:1.3 go build -v

This will add your current directory as a volume to the container, set the working directory to the volume, and run the command go build which will tell go to compile the project in the working directory and output the executable to myapp. Alternatively, if you have a make file, you can instead run the make command inside your container.

docker run --rm -v "$(pwd)":/usr/src/myapp -w /usr/src/myapp golang:1.3 make

Cross-compile your app inside the docker container.

If you need to compile your application for a platform other than linux/amd64 (like windows/386, for example), the provided cross tags can be used to accomplish this with minimal friction:

docker run --rm -v "$(pwd)":/usr/src/myapp -w /usr/src/myapp -e GOOS=windows -e GOARCH=386 golang:1.3-cross go build -v

Alternatively, build for multiple platforms at once:

docker run --rm -it -v "$(pwd)":/usr/src/myapp -w /usr/src/myapp golang:1.3-cross bash
$ for GOOS in darwin linux; do
>   for GOARCH in 386 amd64; do
>     go build -v -o myapp-$GOOS-$GOARCH
>   done
> done