What Is the Go Workspace Mode Yuki Ito (@mrno110) Go 1.18 Release Party

Merpay / Mercoin Architect Mercari Microservices Platform CI/CD Yuki Ito @mrno110

Disclaimer $ go version go version go1.18rc1 linux/amd64 As of this writing...

Agenda ɾBackground ɾWorkspace Mode ɾUse cases

Background ɾgithub.com/110y/gwdemo1 ɾgithub.com/110y/gwdemo2 ɾgithub.com/110y/gwdemo3 Let's assume we develop 3 modules

Background gwdemo3 gwdemo2 gwdemo1 Let's assume we develop 3 modules

Background gwdemo3 package gwdemo3 import "fmt" func Hello(s string) string { return fmt.Sprintf("Hello, %s!", s) }

Background gwdemo1 gwdemo2 package main import ( "fmt" "github.com/110y/gwdemo3" ) func main() { fmt.Println(gwdemo3.Hello("Workspace")) } package main import ( "fmt" "github.com/110y/gwdemo3" ) func main() { fmt.Println(gwdemo3.Hello("Generics")) }

Background When we add a new feature to gwdemo3... package gwdemo3 import "fmt" func Hello(s string) string { return fmt.Sprintf("Hello, %s!", s) } func Bye(s string) string { return fmt.Sprintf("Bye, %s!", s) }

Background And want to use it on gwdemo1 and gwdemo2 locally... package main import ( "fmt" "github.com/110y/gwdemo3" ) func main() { fmt.Println(gwdemo3.Hello("Workspace")) fmt.Println(gwdemo3.Bye("Workspace")) }

Background We have to add a replace directive to the go.mod fi le module github.com/110y/gwdemo1 go 1.18 require github.com/110y/gwdemo3 v0.0.0-20220218011518-502c64a9beed replace github.com/110y/gwdemo3 => ../gwdemo3

Background Problem ɾHave to add replace directive to each module's go.mod fi le. ɾHave to remove replace directive before submitting the code.

Background But working with the replace directive can often be awkward: each module developer might have working versions at di ff erent location on disk, so having the directive in a fi le that needs to be distributed with the module isn't a good fi t for all use cases. https://go.googlesource.com/proposal/+/master/design/45713-workspace.md Proposal: Multi-Module Workspaces in cmd/go

Agenda ɾBackground ɾWorkspace Mode ɾUse cases

Workspace Mode gwdemo3 gwdemo2 gwdemo1

Workspace Mode Workspace gwdemo3 gwdemo2 gwdemo1

Workspace Mode $ mkdir gwdemo-workspace $ cd gwdemo-workspace $ git clone https://github.com/110y/gwdemo1.git $ git clone https://github.com/110y/gwdemo2.git $ git clone https://github.com/110y/gwdemo3.git Workspace

Workspace Mode Workspace $ go work init ./gwdemo1 ./gwdemo2 ./gwdemo3

Workspace Mode go work init creates go.work fi le go 1.18 use ( ./gwdemo1 ./gwdemo2 ./gwdemo3 ) go.work

Workspace Mode $ tree . . ├── go.work ├── gwdemo1 │ ├── go.mod │ ├── go.sum │ └── main.go ├── gwdemo2 │ ├── go.mod │ ├── go.sum │ └── main.go └── gwdemo3 ├── go.mod └── gwdemo3.go

Workspace Mode $ cd gwdemo1 $ go env GOWORK /path/to/gwdemo-workspace/go.work Workspace

Workspace Mode $ go help work ... To determine whether the go command is operating in workspace mode, use the "go env GOWORK" command. This will specify the workspace file being used. ... Workspace

Workspace Mode package gwdemo3 import "fmt" func Hello(s string) string { return fmt.Sprintf("Hello, %s!", s) } func Bye(s string) string { return fmt.Sprintf("Bye, %s!", s) } gwdemo3

Workspace Mode package main import ( "fmt" "github.com/110y/gwdemo3" ) func main() { fmt.Println(gwdemo3.Hello("Workspace")) fmt.Println(gwdemo3.Bye("Workspace")) } gwdemo1

Workspace Mode $ cd gwdemo1 $ go env GOWORK /path/to/gwdemo-workspace/go.work $ go run . Hello, Workspace! Bye, Workspace! Workspace

Problem ✅ Have to add replace directive to each module's go.mod fi le. ✅ Have to remove replace directive before submitting the code. Workspace Mode

Workspace Mode $ cd gwdemo1 $ go env GOWORK /path/to/gwdemo-workspace/go.work $ GOWORK=off go run . # github.com/110y/gwdemo1 ./main.go:12:22: undefined: gwdemo3.Bye Check the actual behavior with GOWORK=o f

Workspace Mode -work fi le fl ag...? https://go-review.googlesource.com/c/go/+/385995/

Agenda ɾBackground ɾWorkspace Mode ɾUse cases

Use cases Microservice Chassis Pattern https://microservices.io/patterns/microservice-chassis.html

Use cases chassis application template

Use cases chassis application template Workspace

Use cases Multi Modules Monorepo ├── cmd │ ├── app1 │ │ ├── go.mod │ │ └── main.go │ ├── app2 │ │ ├── go.mod │ │ └── main.go │ └── app3 │ ├── go.mod │ └── main.go ├── go.work └── pkg ├── echo │ ├── echo.go │ └── go.mod └── hello ├── go.mod └── hello.go

Workspace Mode Workspace gwdemo3 gwdemo2 gwdemo1