Migrating Projects from Dep to Go Modules

Go Modules are the future of Go package management . They have been available to try since Go 1.11, and will be the default behaviour from Go 1.13.

I’m not going to go over (pun-intended) how a package manager works in this article. I will be strictly talking about the path to upgrade existing projects usingdepto Go modules.

Spoiler alert… It’s easy!

In my examples I will be using our proprietary (and therefore private) package github.com/kounta/luigi (more on this later). It contains all sorts of top secret stuff that I can’t talk about. Let’s just say that it is used by several of our other projects written in Go. A perfect candidate.

First, we need to initialise the module:

Just two lines of output (but they are lovely):

Yep. That’s right. It’s already migrated all the dependencies fromdepright out of the box. Woot!

Now you should see a new file calledgo.modwhich looks something like this:

There were many morerequires, but I removed most of them to keep it brief.

Likedepthat has a separate toml and lock file, we need to generate thego.sumfile. Simple run (this also validates everything is OK):

Now you can remove theGopkg.lockandGopkg.tomland commit the newgo.modandgo.sumfiles.

Travis CI

If you are using Travis CI you will need to enable modules by setting an environment variable until it becomes the default setting in Go 1.13:

Private Repositories

If you need to import from a private repository you may see an error like:

This is misleading. What it’s really trying to say is that it recognises what do with the URL (in this case it is github.com). However, it can’t find the repository because GitHub will not confirm its existence.

Fixing it is pretty straight forward:

1. Log into your Github account and goto Settings > Personal access tokens.

2. Create a new token and make sure you check the permission to allow it access to private repositories.

3. Then run: