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Setting up Go's dep Tool to manage dependencies

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As discussed in my first post about Go, out of the box Go does not have a clear way of managing dependencies like Node's npm for example.

The official recommended way of managing dependencies in Go is to use the dep framework. The trickiest thing about this is that dep seems to be very opinionated about where your Go projects should live. But with this enforced convention comes some really great automation. Once set up properly you go into the root of your project and run dep init. This then looks through the imports on your GOPATH, works out what dependencies you need and created a toml with these dependencies and fixed versions (where possible). This also creates a npm style lock file for consistent build across machines. More details on these mechanics can be found here.

Setting up Dep

Environment Variable Setup

To setup dep properly I had to first set the below environment variables in my .zshrc file:

### Go ###
export GO_HOME="/usr/lib/go-1.9/bin"
export GOPATH="/home/youruser/code/go"
export GOROOT="/usr/local/go"

export PATH=$PATH:~/bin:$GOROOT/bin:$GOPATH/bin

In the above:

  • $GOROOT/bin: puts the core go binaries and development tools onto your path
  • $GOPATH/bin: anything you go get url/package which installs as a binary and is placed under bin will be on your path

Your GOPATH can refer to any path you want but should generally stay fixed to one place as any binaries that you go get will have to be retrieved again.

Installing dep

Once this is done install dep as described here

dep lifecycle

Bootstrapping a Project

You need to setup the initial folder structure of your project that must conform with deps conventions as described here and as illustrated below:

mkdir -p $GOPATH/src/github.com/me/example
cd $GOPATH/src/github.com/me/example

Just to illustrate what dep init does before running init I listed my new directory:

> ls -R $GOPATH
ls -R $GOPATH
/home/youruser/code/go:
src

/home/youruser/code/go/src:
github.com

/home/youruser/code/go/src/github.com:
me

/home/youruser/code/go/src/github.com/me:
example

/home/youruser/code/go/src/github.com/me/example:

Then from $GOPATH/src/github.com/me/example I ran dep init:

ls -R $GOPATH
/home/youruser/code/go:
pkg  src

/home/youruser/code/go/pkg:
dep

/home/youruser/code/go/pkg/dep:
sources

/home/youruser/code/go/pkg/dep/sources:

/home/youruser/code/go/src:
github.com

/home/youruser/code/go/src/github.com:
me

/home/youruser/code/go/src/github.com/me:
example

/home/youruser/code/go/src/github.com/me/example:
Gopkg.lock  Gopkg.toml  vendor

/home/youruser/code/go/src/github.com/me/example/vendor:

Adding a New Dependency to a Project

Once you have dep setup for a project you can get it to add new dependencies for you from the root of the project by running: dep ensure -add sourceUrl/package/path

If you get an error like no dirs contained any Go code you will need to create a main.go file (touch main.go) and add a main method to it. dep ensure seems to need at least one Go file to exist before it adds dependencies to your toml and lock files.

package main

function main() {

}

Removing a Dependency from a Project

If you need to remove a dependency you:

  • Remove usages of that dependency from the code
  • Run dep ensure from the root of the project
    • This will automatically remove the dependency from the lock file and vendor folder
  • You will have to manually remove the dependency from the toml file