Embed files in Go

In this post, I will show you a tip to embed files in Go (golang), which, in facts, reads file contents into a variable.

Starting from Go 1.16+, Go developers can easily read files using the embed package, which saves file contents into string, []byte or embed.FS format.

Let say, there has this file data.txt in current directory:

this file content should be embedded in go program

We then can use embed to read this file content as following:

package main

import _ "embed"

//go:embed "data.txt"
var contents string

func main() {
	println(contents)
}

The instruction go:embed "data" says that, we would like to read whole file content and store into the below declared variable contents which has string type.

Similarly, we can store contents file byte array []byte like so:

package main

import _ "embed"

//go:embed "data.txt"
var contents []byte

func main() {
	println(string(contents))
}

For a better trick, if there are many files in a directory, we can read them all into a embed.FS variable, then access them as necessary.

For example, we have a directory named data which contains two data files companies.txt and countries.txt. We will access and read their contents like this:

package main

import (
	"embed"
	_ "embed"
)

//go:embed "data/*"
var fs embed.FS

func main() {
	companies, _ := fs.ReadFile("data/companies.txt")
	println("Companies: \n" + string(companies))

	countries, _ := fs.ReadFile("data/countries.txt")
	println("Countries: \n" + string(countries))
}

That’s how you embed files in Go. Have fun!