//go:embed template

This Go code embeds files from your project into the compiled binary.

import "embed"

//go:embed templates
var embeddedTemplates embed.FS

What it means:

import "embed" enables Go’s built-in embedding feature.

//go:embed templates tells the Go compiler to include the templates directory in the final binary.

var embeddedTemplates embed.FS stores those embedded files in an embed.FS, which behaves like a read-only filesystem.

Example project:

myapp/
  main.go
  templates/
    index.html
    layout.html

Example usage:

package main

import (
	"embed"
	"fmt"
	"log"
)

//go:embed templates
var embeddedTemplates embed.FS

func main() {
	data, err := embeddedTemplates.ReadFile("templates/index.html")
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(string(data))
}

Important detail: the path passed to ReadFile includes templates/.

So this works:

embeddedTemplates.ReadFile("templates/index.html")

But this does not:

embeddedTemplates.ReadFile("index.html")

unless you embed the files differently.

A common pattern with HTML templates:

package main

import (
	"embed"
	"html/template"
	"net/http"
)

//go:embed templates
var embeddedTemplates embed.FS

func main() {
	tmpl := template.Must(template.ParseFS(
		embeddedTemplates,
		"templates/*.html",
	))

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		tmpl.ExecuteTemplate(w, "index.html", nil)
	})

	http.ListenAndServe(":8080", nil)
}

This is useful because your app can run without needing a separate templates folder next to the executable. The template files are baked into the binary at build time.