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Modules

18 July 2018

Reston, VA

Chris Hines

Comcast

@chris_csguy

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Modules

Executive Summary

The Road Here

Structure

User Experience

Inner Workings

The Road Ahead

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Executive Summary

Modules

  • Versioned Packages
  • Built Into the Go Tool
  • Repeatable Builds
  • No GOPATH

{

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The Road Here

Modules

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Milestones

The Road Here

  • GOPATH 2012 Go 1.0
  • goven 2012
  • godep 2013
  • gopkg.in 2014
  • glide 2014
  • gb 2015 (April)
  • govendor 2015 (April)
  • vendor dir 2015 (June) Go 1.5 -> 1.6
  • dep 2017
  • go mod 2018 Go 1.11 -> 1.12

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GOPATH

The Road Here

src/

github.com/golang/example/

.git/ # Git repository metadata

hello/

hello.go # command source

outyet/

main.go # command source

main_test.go # test source

stringutil/

reverse.go # package source

reverse_test.go # test source

golang.org/x/image/

.git/ # Git repository metadata

bmp/

reader.go # package source

writer.go # package source

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GOPATH

The Road Here

Configuration by convention enabled

  • go get
  • go build
  • go test

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Nope

Repeatable Builds?

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Experimentation

The Road Here

  • GOPATH 2012 Go 1.0
  • goven 2012
  • godep 2013
  • gopkg.in 2014
  • glide 2014
  • gb 2015 (April)
  • govendor 2015 (April)
  • vendor dir 2015 (June) Go 1.5 -> 1.6
  • dep 2017
  • go mod 2018 Go 1.11 -> 1.12

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Codification

The Road Here

  • GOPATH 2012 Go 1.0
  • goven 2012
  • godep 2013
  • gopkg.in 2014
  • glide 2014
  • gb 2015 (April)
  • govendor 2015 (April)
  • vendor dir 2015 (June) Go 1.5 -> 1.6
  • dep 2017
  • go mod 2018 Go 1.11 -> 1.12

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Unification

The Road Here

  • GOPATH 2012 Go 1.0
  • goven 2012
  • godep 2013
  • gopkg.in 2014
  • glide 2014
  • gb 2015 (April)
  • govendor 2015 (April)
  • vendor dir 2015 (June) Go 1.5 -> 1.6
  • dep 2017
  • go mod 2018 Go 1.11 -> 1.12

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Redesign

The Road Here

  • GOPATH 2012 Go 1.0
  • goven 2012
  • godep 2013
  • gopkg.in 2014
  • glide 2014
  • gb 2015 (April)
  • govendor 2015 (April)
  • vendor dir 2015 (June) Go 1.5 -> 1.6
  • dep 2017
  • go mod 2018 Go 1.11 -> 1.12

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Structure

Modules

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A module is

Structure

  • A collection of related Go packages
  • The unit of code interchange and versioning

​

​

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Filesystem Structure

Structure

<any-path>/

go.mod # module file

main.go # command source

<any-path>/

.git/ # optional

go.mod # identifies the module root

hello.go # package source

hello_test.go # test source

stringutil/

reverse.go # package source

reverse_test.go # test source

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go.mod

Structure

module example.com/hello

​

Module Path

The import path prefix of the module.

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go.mod

Structure

module example.com/hello

​

require (

golang.org/x/text v0.3.0

gopkg.in/yaml.v2 v2.1.0

)

Dependencies

List of modules we depend on and the minimum version we can use.

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go.mod

Structure

module example.com/hello

​

require (

golang.org/x/text v0.3.0

gopkg.in/yaml.v2 v2.1.0

)

​

exclude github.com/go-stack/stack v1.6.0

Exclusions

List of module versions we reject for some reason.

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go.mod

Structure

module example.com/hello

​

require (

golang.org/x/text v0.3.0

gopkg.in/yaml.v2 v2.1.0

)

​

exclude github.com/go-stack/stack v1.6.0

​

replace (

github.com/go-stack/stack v1.4.0 => ../stack/

golang.org/x/text => github.com/pkg/errors v0.8.0

)

​

Replacements

List of module [versions] we replace with something else.

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User Experience

Modules

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Go 1.11 Module Support

User Experience

  • Inside GOPATH — Status Quo
  • Outside GOPATH — Modules reign
  • GO111MODULE environment variable
    • auto (default)
    • on
    • off

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Commands

User Experience

go mod -init [-module=module-path]

go build

go test

go list -m [-u] all

go mod -sync

go help modules

go help mod

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go get (module remix)

User Experience

go get github.com/gorilla/mux@latest

same (@latest is default for 'go get')

go get github.com/gorilla/mux@v1.6.2

records v1.6.2

go get github.com/gorilla/mux@e3702bed2

records v1.6.2

go get github.com/gorilla/mux@c856192

records v0.0.0-20180517173623-c85619274f5d

go get github.com/gorilla/mux@master

records current meaning of master

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Live demo

User Experience

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Inner Workings

Modules

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Live Demo

Inner Workings

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The Road Ahead

Modules

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Release Plans

The Road Ahead

  • Module support merged July 12
  • Opt-in feature in Go 1.11 (end of Aug?)
  • Default in Go 1.12

​

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Ultimate Goals

The Road Ahead

  • Add versions to the Go vocabulary of
    • Developers
    • Tools
  • Break free of GOPATH
  • Minimize need for vendor dirs

​