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Kenta Takeuchi
Kenta Takeuchi

Posted on • Originally published at bmf-tech.com

Using Workspace Mode with Go's Multi-Module Structure

#go

This article was originally published on bmf-tech.com.

I had never used the Workspace mode added in Go 1.18, so I decided to give it a try.

What is Workspace Mode?

A feature to facilitate Go's multi-module structure.

How to Use Workspace Mode

Prepare the following structure:

.
├── bar
│   └── bar.go
└── foo
    └── foo.go
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// foo.go
package foo

func Foo() string {
    return "foo"
}
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// bar.go
package bar

func Bar() string {
    return "bar"
}
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Execute the following command in the foo directory to set up go.mod.

go mod init example.com/foo
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Similarly, execute the following command in the bar directory to set up go.mod.

go mod init example.com/bar
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Next, create a cmd directory and create a main.go file as follows:

package main

import (
    "example.com/bar"
    "example.com/foo"
)

func main() {
    println(foo.Foo())
    println(bar.Bar())
}
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Set up go.mod in the cmd directory as well.

go mod init example.com/cmd
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At this point, the structure will be as follows:

.
├── bar
│   ├── bar.go
│   └── go.mod
├── cmd
│   ├── go.mod
│   └── main.go
└── foo
    ├── foo.go
    └── go.mod
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In the root directory, execute the following command to configure the workspace.

go work init foo bar cmd
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A file named go.work is created.

go 1.21.1

use (
    ./bar
    ./cmd
    ./foo
)
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Verify that go run cmd/main.go can be executed.

// Execution result
foo
bar
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Next, let's add a module called baz.

.
├── bar
│   ├── bar.go
│   └── go.mod
├── baz
│   ├── baz.go
│   └── go.mod
├── cmd
│   ├── go.mod
│   └── main.go
├── foo
│   ├── foo.go
│   └── go.mod
└── go.work
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// baz.go
package baz

func Baz() string {
    return "baz"
}
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Execute go mod init example.com/baz to generate go.mod like the other modules.

Next, add baz to main.go.

package main

import (
    "example.com/bar"
    "example.com/baz"
    "example.com/foo"
)

func main() {
    println(foo.Foo())
    println(bar.Bar())
    println(baz.Baz())
}
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Return to the root and execute go work use baz to add the module, and baz will be added to go.work.

go 1.21.1

use (
    ./bar
    ./baz
    ./cmd
    ./foo
)
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Execute go run cmd/main.go and confirm that baz is added to the output.

// Execution result
foo
bar
baz
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Impressions

I thought the multi-module structure was cumbersome, so I'm glad it has become simpler.

References

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