Verifying a session in Go

Protect your backend APIs

Go makes it really easy to create a simple HTTP server, and Clerk makes it simple to authenticate any request. The following examples shows how to verify a session and retrieve the corresponding user.


package main
 
import (
	"net/http"
	"strings"
 
	"github.com/clerk/clerk-sdk-go/clerk"
)
 
func main() {
	client, _ := clerk.NewClient({{secret}})
 
	http.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
		// get session token from Authorization header
		sessionToken := r.Header.Get("Authorization")
		sessionToken = strings.TrimPrefix(sessionToken, "Bearer ")
 
		// verify the session
		sessClaims, err := client.VerifyToken(sessionToken)
		if err != nil {
			w.WriteHeader(http.StatusUnauthorized)
			w.Write([]byte("Unauthorized"))
			return
		}
 
		// get the user, and say welcome!
		user, err := client.Users().Read(sessClaims.Claims.Subject)
		if err != nil {
			panic(err)
		}
 
		w.Write([]byte("Welcome " + *user.FirstName))
	})
 
	http.ListenAndServe(":8080", nil)
}

Using middleware

The Clerk SDK also provides a simple middleware that adds the active session to the request's context.


package main
 
import (
	"net/http"
 
	"github.com/clerk/clerk-sdk-go/clerk"
)
 
func main() {
	client, _ := clerk.NewClient({{secret}})
 
	mux := http.NewServeMux()
 
	injectActiveSession := clerk.WithSessionV2(client)
	mux.Handle("/hello", injectActiveSession(helloUserHandler(client)))
 
	http.ListenAndServe(":8080", mux)
}
 
func helloUserHandler(client clerk.Client) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		ctx := r.Context()
 
		sessClaims, ok := clerk.SessionFromContext(ctx)
		if !ok {
			w.WriteHeader(http.StatusUnauthorized)
			w.Write([]byte("Unauthorized"))
			return
		}
 
		user, err := client.Users().Read(sessClaims.Claims.Subject)
		if err != nil {
			panic(err)
		}
 
		w.Write([]byte("Welcome " + *user.FirstName))
	}
}