Published on January 10, 2014
One of the most contentious aspects of Go is the simplistic approach to managing your dependencies and workspace. Go relies on the
$GOPATH environment variable, which should point to the root directory that contains all of your Go software. This works well with a monorepo, which Google is famous for, but it’s a bit of a pain for the rest of us.
The fact of life outside of Google is that most developers either prefer or are forced to keep their projects separated. So how do we make that work nicely with having a single
The most common solution I’ve seen in the wild is to either wrap the
go command or add a separate script that simply sets
$GOPATH to the current working directory. This can work, but is fairly manual, and can get confusing if you’re in a subdirectory of your project.
Instead, I’d like to introduce you to a wonderfully simple tool that I recently ran across: Direnv.
Direnv’s mission is to “unclutter your .profile,” which it delivers on. More accurately…
direnv is a shell extension that loads different environment variables depending on your path.
Instead of putting every environment variable in your
~/.profile, have directory-specific
.envrcfiles for your
LIBRARY_PATHor other environment variables.
It does some of the job of rvm, rbenv or virtualenv but in a language-agnostic way.
Here’s how you can use direnv as the magic bullet for managing your
$ brew update $ brew install direnv $ echo 'eval "$(direnv hook bash)"' >> ~/.bashrc
Now, in each of your go projects, create a
~/some/go/project $ echo 'export GOPATH=$(PWD)' > .envrc
The first time you
cd into a directory with a
.envrc file, it will refuse to load the file. This is to protect you, since the contents of the
.envrc will be executed by your shell, and they might come from untrusted sources. Simply run
direnv allow .envrc, and it will trust that file until the next time it changes.
From now on, your
$GOPATH will be correctly set if and only if you’re somewhere inside that project.
~ $ cd some/go/project/ direnv: loading .envrc direnv export: +GOPATH ~/some/go/project $ echo $GOPATH /Users/tsaleh/some/go/project ~/some/go/project $ cat .envrc export GOPATH=$(PWD) ~/some/go/project $ cd ~/ direnv: unloading direnv export: -GOPATH ~ $ echo $GOPATH # Nothing!
So easy it’s built in!
In fact, this is so useful, it’s actually built into direnv! Instead of setting the variable manually in your
.envrc file, you can use the
layout function that direnv provides:
~/some/go/project $ echo 'layout go' > .envrc