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@SilverCory
Created September 6, 2023 13:24
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Golang Gin SPA serving using embedded fs

Golang Gin SPA serving using embedded fs.

Usage:

File Structure:

  • Go Project Root
    • Go files and project
    • SPA FE (in my case ui
      • spa.go

Go Use:

  • Create a webserver
  • Register the spa middleware as the last middleware.
    • Call ui.NewHandler().Register(e).

SPA Use:

  • In the file above it's configured to use the dist folder.
    • This is where your project should build into.
package ui
import (
"embed"
"github.com/gin-gonic/gin"
"io/fs"
"net/http"
"os"
"path"
"reflect"
"runtime"
"strings"
"sync"
)
//go:embed dist
var Content embed.FS
// uiPath is the root path for the UI to sit at.
const uiPath = "/"
type Handler struct {
fileSystem http.FileSystem
fileServer http.Handler
once sync.Once
serveSPAFuncName string
}
func NewHandler() *Handler {
// Open the dist folder.
authorizeSite, err := fs.Sub(Content, "dist")
if err != nil {
panic(err)
}
fileSystem := http.FS(authorizeSite)
return &Handler{
fileSystem: fileSystem,
fileServer: http.StripPrefix(uiPath, http.FileServer(fileSystem)),
}
}
func (h *Handler) Register(e *gin.Engine) {
e.Use(h.ServeSPA)
}
func (h *Handler) ServeSPA(c *gin.Context) {
h.once.Do(func() {
h.serveSPAFuncName = runtime.FuncForPC(reflect.ValueOf(h.ServeSPA).Pointer()).Name()
})
// Ensure it's only get and head requests
if c.Request.Method != http.MethodGet && c.Request.Method != http.MethodHead {
c.Next()
return
}
// Ensure we're the last handler
names := c.HandlerNames()
if len(names) != 0 && names[len(names)-1] != h.serveSPAFuncName {
c.Next()
return
}
filePath := c.Request.URL.Path
// Serve index, it's the index.
if filePath == uiPath {
h.fileServer.ServeHTTP(c.Writer, c.Request)
return
}
// Open the file check it exists
f, err := h.fileSystem.Open(strings.TrimPrefix(path.Clean(filePath), "/"))
if err == nil {
_ = f.Close()
}
// If it doesn't exist use the index.
var req = c.Request
if os.IsNotExist(err) {
req = c.Request.Clone(c.Request.Context())
req.URL.Path = uiPath
}
// Serve the file
h.fileServer.ServeHTTP(c.Writer, req)
}
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