gockerize

Build static golang binaries and package them into minimal docker containers

License

BSD 3-Clause, see accompanying LICENSE file.

Requirements

• bash
• docker 1.5+

Usage

gockerize <image> <package> [<source> [<mapping> [<Dockerfile>]]]

The default use case is to call the script from the root directory of the package being built, with any dependencies vendored in and the Dockerfile at the root of the package.

Arguments

The image argument determines the name of the resulting Docker image.

The package argument is the fully qualified name of the package being built.

The source argument can be used to easily include non-vendored dependencies into the build context. For instance, given the following hierarchy:

src/
    acme.com/
        common/
        foo/

Where foo is the service to be built and common is a package it depends on.

The following command can be used, from src/acme.com/foo :

gockerize foo acme.com/foo ..

This will result in all of src/acme.com being used as build context, under $GOPATH/src/acme.com.

Similarly, mapping can be changed from its default value to accommodate source layouts that deviate from golang's conventions and Dockerfile can point to a Dockerfile at a non-default location, including outside of the Docker build context.

The contents of the GOARGS environment variable are passed to the go build command inside the container. Among other things, this makes it easy to use custom build tags.

Dockerfile

A typical Dockerfile may look like:

FROM scratch
ADD bin/foo /foo
EXPOSE 12345
ENTRYPOINT [ "/foo" ]

The Docker image is built within a temporary container and its build context is limited to the content of GOPATH on that container, hence the reference to bin/foo which is the location of the binary produced by compiling package acme.com/foo.

Dependency resolution

For ease of use, gockerize uses go get to automatically fetch remote dependencies from github and other public repositories supported by default, however, vendored dependencies should be preferred as they ensure repeatable build.

By default, gockerize uses Go 1.5.3 and enables GOVENDOREXPERIMENT. However, it is possible to use any desired version of Go by setting the GOVERSION environment variable appropriately, for instance GOVERSION=1.9.2 to build with Go 1.9.2

Patching standard lib

Fully static builds allow easy patching of the standard library. gockerize leverages that by automatically applying patches found in the patches subdir of the package being built.

Care should be taken that the patches cleanly apply against the version of Go used in the container (1.5.3 at this time).