Refactoring to Modules - Why, How and Everything Else I Can Fit In 45 Minutes…

@JFrog | jfrog.com/shownotes | #GoCenter | @LeonStigter
Refactoring to modules
Why, How and Everything Else I Can Fit In 45
Minutes…

A Big thanks to our hosts of today

https://jfrog.com/shownotes
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& Ratings
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Who am I?
• Developer Advocate
• Passionate about Serverless,
Containers, and all things
Cloud
• I love dadjokes, cheesecake
and Go
@LeonStigter
Leon Stigter, Developer Advocate

Dadjokes?
What happens when you hold a Unix terminal to your ear?
You can hear the C

Let’s travel back in time…

When did you start with Go?
Let’s turn to the audience for a poll…
1.0
2012
1.2
2013
1.5
2015
1.8
2017
1.11
2018

A quick history of go
Go 1.0
First major
milestone as a
long term
stable release
2012 2015
Go 1.5
First release to
no longer use C
(except for cgo)
2017
Go 1.8
Introduction of
Go plugins
2018
Go 1.11
This is where
the magic is! (at
least for this
talk J)

Dependency Management…
So what is that magic?

“Tis impossible to be sure of anything
but Death and Taxes”
- Christopher Bullock

At JFROG, we really like pipelines and promotions
CI
SERVER
Integration System Testing
If quality
requirments are hit
If quality
requirments are hit
If quality
requirments are hit
Staging
- Quality gates -
Production
1 2 3 4
*

At jfrog, we absolutely love Immutable and repeatable builds
The best way to guarantee issues is force push
Immutable dependencies
Who doesn’t remember left-pad with Node.js?
Lost Dependencies
Even build when GitHub is down!?
Internet Issues

Show me something already!
¯_(ツ)_/¯

Recapping, gocenter is…

Discovery
Go
Notifier
Go
Processor
Go
Validator
Go
UI Backend
Go
UI
Node.js
Built out of a few microservices

Start with the why…

In Go, We had a
Problem…
Source: Go at Google https://www.infoq.com/presentations/Go-Google

One easy solution…?
Dependencies are sources!
Remote imports are in VCS
Dump everything into a single folder
Compile…
Profit!!

• Which dependencies I use?
• Which dependencies you
used?
• Which dependencies I should
use?
• Which code I’m editing right
now?
• What is going on?!
But… how do I know…

Vendoring – the worst kind of forking
“Copy all of the files at some version from one version
control repository and paste them into a different version
control repository”

• History, branch, and tag information
is lost
• Pulling updates is impossible
• It invites modification, divergence,
and bad fork
• It wastes space
• Good luck finding which version of
the code you forked
But what is wrong with vendoring?

Build your own dependency manager…
“It’s not the role of the tooling provided by
the language to dictate how you manage
your code (...)”

• Working in project directories
• Local cache for dependencies
• Version declarations
• Conflict resolution
Go dep – Proper dependency management?

Who is using Go modules?
Let’s turn to the audience for another poll…
Yes No

Module
A module is a collection of
related Go packages that
are versioned together as a
single unit.
Let’s go over some definitions

Sources
A module is a tree
(directory) of Go source
files with a go.mod file in
the root directory.

Version Control
Most often, a single version-
control repository
corresponds exactly to a
single module

Set the environment variable
GO111MODULE to ON
Use go outside of your
$GOPATH
Using go modules
1 2

mkdir mymodule
cd mymodule
go mod init github.com/retgits/mymodule
Creating a module

• Import dependencies from Gopkg.lock
go mod init <module path>
• Remove unnecessary imports and add indirect imports
go mod tidy
• Delete the vendor folder
rm –rf vendor/
• Delete Gopkg files
rm Gopkg.*
Moving from DEP to modules

Go.mod by any other name…
Would probably not work…

module github.com/retgits/mymodule
go 1.12
require (
github.com/naoina/go-stringutil v0.1.0
github.com/some/dependency v1.2.3
github.com/google/go-github/v25 v25.0.1
)
replace github.com/some/dependency github.com/retgits/dependency
versioning

go 1.12
require (
)
replace github.com/some/dependency github.com/retgits/dependency
Replacing packages

go 1.12
require (
)
replace github.com/some/dependency ../../Downloads/dependency
Works with local folders too!

• You can create the vendor folder
go mod vendor
• You can use the vendor folder during builds
go build –mod=vendor
This does mean you need to have all dependencies
listed in your go.mod file
But I kinda like the vendor folder?

• If you run `go mod vendor`, the `vendor` directory it creates should
reflect your `replace` directives. (That is: it should put the
replacement content in the `vendor` directory rather than the
original module content.)
• But if as you say, `-mod=vendor` bypasses go.mod that makes
sense.
• So does `-mod=vendor` require you to have vendored all your
dependencies? (edited)
• Yes. If you have a complete `go.mod`, `go mod vendor` will do that
for you (as Bryan said, including taking into account `replace`
statements).
But I kinda like the vendor folder?

Houston… I think I lost my module?

The <module>@v<version> construct should be immutable
That means that
github.com/retgits/checkiday/@v/v1.0.0
Should forever be the same…
Modules are immutable

But are they really?
”Friends don’t let friends do git push -f”
- Aaron Schlesinger

Using the goproxy variable
export GOPROXY=https://myawesomeproxy.com
go get github.com/retgits/checkiday

Keeping modules
Immediate access, not shared, can be wiped…
Local cache ($GOPATH/pkg/mod)
Fast access, requires infra, shared across devs
Organizational cache (private proxy)
Highly available, CDN, no infra, free
Public cache (public proxy)

And also faster builds…

Before modules
go get github.com/project-flogo/cli
git clone https://github.com/project-flogo/cli
<build module locally>
With modules
go get github.com/project-flogo/cli
GET github.com/project-flogo/cli/@v/list
GET github.com/project-flogo/cli/@v/v1.0.0.mod
GET github.com/project-flogo/cli/@v/v1.0.0.zip
Go get my module!

• If you haven’t, start with Go modules:
GO111MODULE=on
• Start working outside of your $GOPATH
• Use a public proxy server for immutable Go modules (like
GoCenter.io)
• Think about running your own proxy server (like Project
Athens)
Final thoughts

There’s one more thing…
But before I go…

What is a 5* module for you?
We talked about modules a bit…

• https://jfrog.com/shownotes
• @JFrog
• #GoLang
• https://gocenter.io
• @LeonStigter
Twitter, ads, and Q&a

Thank you!

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