How Can I Embed Files into My Go Binaries Using `go:embed` and `go generate`?

Embedding Files into Go Binaries

In Go, you may encounter scenarios where you want to include files within the compiled executable rather than distributing them separately. This guide explores two methods for embedding files in your Go binaries: using go:embed directive and the go generate command.

Embedding Files with go:embed

Introduced in Go 1.16, the go:embed directive provides a straightforward way to embed files into your binaries. This directive allows you to directly define a variable that holds the embedded file as a string, byte slice, or embed.FS type. For example:

import "embed"

//go:embed hello.txt
var s string

Using go:embed streamlines the process of embedding files, especially when dealing with multiple or dynamically generated files.

Embedding Files with go generate

Prior to Go 1.16, the go generate command offered an alternative method for embedding files. This method involves creating a custom script that reads the files and generates a Go file containing the embedded files as string literals.

1. Create a script to generate the Go file:
   In a separate script file, read the text files and write them as string literals into a new file. For instance:

   package main
   
   import (
       "fmt"
       "io/ioutil"
       "os"
       "strings"
   )
   
   // Reads all .txt files in the current folder
   // and encodes them as string literals in textfiles.go
   func main() {
       fs, _ := ioutil.ReadDir(".")
       out, _ := os.Create("textfiles.go")
       out.Write([]byte("package main \n\nconst (\n"))
       for _, f := range fs {
           if strings.HasSuffix(f.Name(), ".txt") {
               out.Write([]byte(strings.TrimSuffix(f.Name(), ".txt") + " = `"))
               f, _ := os.Open(f.Name())
               io.Copy(out, f)
               out.Write([]byte("`\n"))
           }
       }
       out.Write([]byte(")\n"))
   }

2. Add a special comment to your main Go file:
   Add a special comment containing the go generate command in your main Go file. This comment tells Go to run the specified script before compiling.

   //go:generate go run scripts/includetxt.go

3. Compile your program:
   Execute go generate to run the script and generate the textfiles.go file, containing the embedded files as string literals. Then, build your program using go build.

While go generate provides more flexibility, go:embed is a more modern and convenient approach for embedding files in Go binaries. Choose the method that best suits your development needs.

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