Overview

If you want to vendor your dependencies,  then below command can be used to achieve the same.

go mod vendor

Example

Let’s see an example to better understand. First let’s create a module

go mod init learn

This command will create a go.mod file in the same directory.

module learn

go 1.14

Since it is an empty module it doesn’t have any direct dependency specified yet. Let’s specify a dependency in the go.mod file

module learn

go 1.14

require github.com/pborman/uuid v1.2.1

Create a file named uuid.go in the same directory with the below contents and use the dependency we added earlier in the go.mod file.

uuid.go

package main

import (
	"fmt"
	"strings"

	"github.com/pborman/uuid"
)

func main() {
	uuidWithHyphen := uuid.NewRandom()
	uuid := strings.Replace(uuidWithHyphen.String(), "-", "", -1)
	fmt.Println(uuid)
}

Let’s run the below command

go mod vendor

It will create a vendor directory inside your project directory. The vendor directory will have all the direct and indirect dependencies downloaded. You can also check in the vendor directory to your VCS (Version Control System). This becomes useful in the sense that none of the dependency needs to be downloaded at run time as it is already present in the vendor folder checked into VCS.

-v flag can also be used with go mod vendor. When this flag is provided the command will print all the modules and packages which are vendored

go mod vendor -v