The backstream is a library designed for environments with restricted ingress connections. It enables HTTP servers to establish outbound WebSocket connections to a central HTTP service. Once connected, users can send HTTP requests to the central service, which efficiently forwards them downstream to the appropriate WebSocket-enabled servers, effectively bypassing ingress restrictions.
Write a proxy server.
package main
import (
"context""flag""log/slog""net/http""os""time""github.com/grepplabs/backstream/handler""github.com/grepplabs/backstream/ws"
)
funcmain() {
addr:=flag.String("addr", ":8080", "Listen address")
flag.Parse()
codec:=handler.NewHttpProtoCodec()
proxyHandler:=handler.NewProxyHandler(codec, handler.WithProxyDefaultRequestTimeout(3*time.Second))
logger:=slog.New(slog.NewJSONHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelDebug}))
serve:=ws.NewServe(context.Background(), proxyHandler, codec.MessageCodec(), ws.WithServeLogger(logger), ws.WithRequireClientId(true))
mux:=http.NewServeMux()
mux.HandleFunc("/ws", func(w http.ResponseWriter, r*http.Request) {
serve.HandleWS(w, r)
})
mux.HandleFunc("/", func(w http.ResponseWriter, r*http.Request) {
serve.HandleProxy(w, r)
})
server:=&http.Server{
Addr: *addr,
ReadHeaderTimeout: 3*time.Second,
Handler: mux,
}
iferr:=server.ListenAndServe(); err!=nil {
logger.Error(err.Error())
}
}Write a HTTP service server.
package main
import (
"context""flag""log/slog""net/http""os""github.com/grepplabs/backstream/handler""github.com/grepplabs/backstream/ws"
)
funcmain() {
addr:=flag.String("addr", ":8081", "Listen address")
proxyUrl:=flag.String("proxy-url", "ws://localhost:8080/ws", "Proxy websocket endpoint")
clientID:=flag.String("client-id", "4711", "Client ID")
flag.Parse()
codec:=handler.NewHttpProtoCodec()
logger:=slog.New(slog.NewJSONHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelDebug})).With(slog.String("client-id", *clientID))
mux:=http.NewServeMux()
wsHandler:=handler.NewRecoveryHandler(handler.NewHTTPHandler(func(w http.ResponseWriter, r*http.Request) {
mux.ServeHTTP(w, r)
}, codec), logger)
client:=ws.NewClient(context.Background(), *proxyUrl, wsHandler, codec.MessageCodec(), ws.WithClientLogger(logger), ws.WithClientID(*clientID))
client.Start()
mux.HandleFunc("/test", func(w http.ResponseWriter, r*http.Request) {
w.WriteHeader(200)
})
server:=&http.Server{
Addr: *addr,
Handler: mux,
}
iferr:=server.ListenAndServe(); err!=nil {
logger.Error(err.Error())
}
}Invoke test endpoint against the proxy server.
curl -v -H 'x-backstream-client-id: 4711' http://localhost:8080/test
curl -v -H 'x-backstream-client-id: 4711' -H 'x-backstream-request-timeout: 12s' http://localhost:8080/test