episode27

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Using Go Modules For Your Dependencies

Go in 5 Minutes, episode 27.

In this screencast, we're going to talk about Go Modules to manage our dependencies.

Modules are a brand new dependency management system in Go, and they're here to stay. The modules technology is officially part of the go toolchain starting with version 1.11, and they're really nice. Modules have some features that are familiar to previous dependency management systems, like these:

• Define your dependencies in a file that you can check in with your code
• Keep track of all the dependencies -- including dependencies-of-your-dependencies (AKA transitive dependencies) -- in another file that you can check in with your code
• Keep checksums of all your dependencies (including transitive dependencies), so that things don't change out from under you

But they add some exciting new things too!

• Fetch all your dependencies without learning any other tools
• Delete your vendor/ directory if you want
• Work outside the GOPATH
• Fetch your dependency code from somewhere other than GitHub, GitLab, and other version control systems!
  • More on this in a future episode ...

We're going to show a little bit of how modules work and how you can use them in your code.

Check out the screencast for more!

How To Build This Code

Because Go Modules is built into the go toolchain, building is pretty easy - you don't even need a Makefile or a GOPATH set up!

First, make sure you either don't have this episode27 directory inside your GOPATH, or that you have GO111MODULE set to on like this:

$ export GO111MODULE=on

And then, you should be ready to go!

$ go build -o heygophers .
$ ./heygophers

Once you run ./heygophers, your web server should start up on port 8080, and you can open up the app at http://localhost:8080 in your browser.

Enjoy!

(P.S. for an exciting look under the covers of what the Go Modules system is doing, clear your local modules cache with this command: sudo rm -rf $(go env GOPATH)/pkg/mod)

Show Notes

• Just For Func Intro to Go Modules and SemVer: https://www.youtube.com/watch?v=aeF3l-zmPsY
• Just For Func Migrating Go Modules to v2+: https://www.youtube.com/watch?v=H_4eRD8aegk
• The Go modules wiki: https://github.com/golang/go/wiki/Modules