Dependency Management

Managing Dependencies

For the better part of Go's existence, dependency management was a hotly-contested topic, however, these days there are two very well supported ways to manage your dependencies.

The simplest option

If you are not too concerned about exact versions or are just installing a tool, the easiest way to fetch a dependency remains go get github.com/user/package-that-you-want. This will install the library/tool directly into your GOPATH, make it importable from any of your Go projects, and it'll also be usable as an executable if you put your $GOPATH/bin into your system's PATH as well.

For Larger Projects

When it comes to managing a consistent set of dependencies for a larger project, it is now recommended to use a tool called dep. This is the only dependency management tool that is directly supported and maintained by the Go project itself, and is becoming the defacto standard for Go dependency management. Once you have installed dep by following the relevant instructions here you'll be able to use it for managing dependencies in your project.

The dep tool relies on Go's 'vendor' directory that it is a way for managing project-specific copies of dependencies (similar to Node's node_modules that are managed by NPM). When compiling, Go will first check this 'vendor' directory that is structured similarly to your GOPATH, except for it basically starts with the 'src' part as its root.

NOTE: The primary issue with using the vendor/dep solution for package management is that, especially when writing libraries, it will cause issues for downstream implementers who may have a different copy of those dependencies. This will cause major issues -- unless you always use good interfaces (instead of structs) that Go will be able to actually check for fit at compile time!

Using dep

For the most up-to-date instructions on using dep, it's best to check out their official documentation here.

Keep it Idiomatic!

In Go we:

• Ship new projects using dep to give the best experience possible to collaborators and implementers

• When developing libraries, stick to minimal interfaces so that an implementer with a different set of vendored dependencies, will still be able to pass their data in and out of your library!