UUID without dependencies in Go

Fri, Aug 26, 2016 One-minute read

Today I realized that size of my vendor/ folder in Golang project is around 150M. I am using glide there. There are 24 dependencies (it’s a program with multiple data storage connectors, notifications, etc.), so I decided to review it and reduce amount of 3rd party libraries.

First of all I have checked glide-report and removed 2 unused packages. Go-world has a lot of packages that are awesome and can save your time, but not your program’s performance. I found few packages which I am using as helpers. For example gouuid.

What’s happaned when you run glide get?

  • go build execution time will be increased
  • go run execution time will be increased
  • vendor/ folder size will be increased

So I decided to remove gouuid and use crypto/rand:

package main

import (

func main() {

func uuid() (string, error) {
	b := make([]byte, 16)
	_, err := rand.Read(b)

	if err != nil {
		return "", err

	return fmt.Sprintf("%X-%X-%X-%X-%X", b[0:4], b[4:6], b[6:8], b[8:10], b[10:]), nil

Let’s run it:

go run test.go
2E395F0E-F422-1BD1-608F-C686D39A7DA1 <nil>
1C692140-0E15-8BCD-0738-1583115216A5 <nil>
652ED449-5085-BB13-0905-C5BD859E18A2 <nil>

I am satisfied of this result, though it’s a pseudo-uuid. Also benchmark result of this solution wins 3rd party dependency.

Think twice before go get!