Keep WebSocket connection alive after upgrade in Go - http

Question

I am having issue in keeping websocket connection alive in go. In my code below, I assign 2 different ports to handle websocket (:8080) and for API request (:3300).
There is no issue when I am using websocket handler directly, but using API handler request and making new external request to the websocker handler, the connection closed directly. Any help is appreciated.
package main
import (
"bytes"
"fmt"
"io/ioutil"
"net/http"
"time"
"github.com/gobwas/ws"
"github.com/gobwas/ws/wsutil"
)
func main() {
go websocket()
http.HandleFunc("/ws", func(rw http.ResponseWriter, r *http.Request) {
body, err := ioutil.ReadAll(r.Body)
if err != nil {
http.Error(rw, err.Error(), http.StatusInternalServerError)
return
}
url := fmt.Sprintf("http://127.0.0.1:8080?%s", r.URL.RawQuery)
req, err := http.NewRequest(r.Method, url, bytes.NewReader(body))
if err != nil {
fmt.Println(err)
panic(err)
}
req.Header = make(http.Header)
for h, val := range r.Header {
req.Header[h] = val
}
httpClient := &http.Client{Timeout: time.Second * 10}
httpClient.Do(req)
})
http.ListenAndServe(":3300", nil)
}
func websocket() {
http.ListenAndServe(":8080", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
conn, _, _, err := ws.UpgradeHTTP(r, w)
if err != nil {
fmt.Println(err)
return
}
go func() {
defer conn.Close()
for {
msg, op, err := wsutil.ReadClientData(conn)
if err != nil {
fmt.Println(err)
return
}
err = wsutil.WriteServerMessage(conn, op, msg)
if err != nil {
fmt.Println(err)
return
}
}
}()
}))
}

Answer 1

The code in the question connects to the websocket endpoint using an HTTP request. Upgrade fails as a result.
Use the standard library reverse proxy to proxy the request.
A simpler approach is to is to call the websocket handler directly. Move the handler to a top-level function:
func handleWS(w http.ResponseWriter, r *http.Request) {
conn, _, _, err := ws.UpgradeHTTP(r, w)
if err != nil {
fmt.Println(err)
return
}
go func() {
defer conn.Close()
for {
msg, op, err := wsutil.ReadClientData(conn)
if err != nil {
fmt.Println(err)
return
}
err = wsutil.WriteServerMessage(conn, op, msg)
if err != nil {
fmt.Println(err)
return
}
}
}()
}
Use the handler in both servers.
func main() {
go websocket()
http.HandleFunc("/ws", handleWS)
http.ListenAndServe(":3300", nil)
}
func websocket() {
http.ListenAndServe(":8080", http.HandlerFunc(handleWS))
}