BASED ON THE OFFICIAL GOLANG DOCKER IMAGE
What is Go?
Go (a.k.a., Golang) is a programming language first developed at Google. It is a statically-typed language with syntax loosely derived from C, but with additional features such as garbage collection, type safety, some dynamic-typing capabilities, additional built-in types (e.g., variable-length arrays and key-value maps), and a large standard library.
How to use this image
Start a Go instance in your app
The most straightforward way to use this image is to use a Go container as both the build and runtime environment. In your Dockerfile, writing something along the lines of the following will compile and run your project:
FROM klud/golang:<version> WORKDIR /go/src/app COPY . . RUN go-wrapper download # "go get -d -v ./..." RUN go-wrapper install # "go install -v ./..." CMD ["go-wrapper", "run"] # ["app"]
You can then build and run the Docker image:
$ docker build -t my-golang-app . $ docker run -it --rm --name my-running-app my-golang-app
go-wrapper run includes
set -x so the binary name is printed to stderr on application startup. If this behavior is undesirable, then switching to
CMD ["app"] (or
CMD ["myapp"] if a Go custom import path is in use) will silence it by running the built binary directly.
Compile your app inside the Docker container
There may be occasions where it is not appropriate to run your app inside a container. To compile, but not run your app inside the Docker instance, you can write something like:
$ docker run --rm -v "$PWD":/usr/src/myapp -w /usr/src/myapp golang:1.8 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
Makefile, you can run the make command inside your container.
$ docker run --rm -v "$PWD":/usr/src/myapp -w /usr/src/myapp golang:1.8 make
Cross-compile your app inside the Docker container
If you need to compile your application for a platform other than linux/amd64 (such as windows/386):
$ docker run --rm -v "$PWD":/usr/src/myapp -w /usr/src/myapp -e GOOS=windows -e GOARCH=386 golang:1.8 go build -v
Alternatively, you can build for multiple platforms at once:
$ docker run --rm -it -v "$PWD":/usr/src/myapp -w /usr/src/myapp golang:1.8 bash $ for GOOS in darwin linux; do > for GOARCH in 386 amd64; do > go build -v -o myapp-$GOOS-$GOARCH > done > done
This image is based on the popular Alpine Linux project, available in the alpine official image. Alpine Linux is much smaller than most distribution base images (~5MB), and thus leads to much slimmer images in general.
This variant is highly recommended when final image size being as small as possible is desired. The main caveat to note is that it does use musl libc instead of glibc and friends, so certain software might run into issues depending on the depth of their libc requirements. However, most software doesn't have an issue with this, so this variant is usually a very safe choice. See this Hacker News comment thread for more discussion of the issues that might arise and some pro/con comparisons of using Alpine-based images.
To minimize image size, it's uncommon for additional related tools (such as git or bash) to be included in Alpine-based images. Using this image as a base, add the things you need in your own
Dockerfile (see the alpine image description for examples of how to install packages if you are unfamiliar).