XHandler is a bridge between net/context and http.Handler.
It lets you enforce net/context in your handlers without sacrificing compatibility with existing http.Handlers nor imposing a specific router.
Thanks to net/context deadline management, xhandler is able to enforce a per request deadline and will cancel the context when the client closes the connection unexpectedly.
You may create your own net/context aware handler pretty much the same way as you would do with http.Handler.
Read more about xhandler on Dailymotion engineering blog.
go get -u github.com/rs/xhandler
package main
import (
"log"
"net/http"
"time"
"github.com/rs/cors"
"github.com/rs/xhandler"
"golang.org/x/net/context"
)
type myMiddleware struct {
next xhandler.HandlerC
}
func (h myMiddleware) ServeHTTPC(ctx context.Context, w http.ResponseWriter, r *http.Request) {
ctx = context.WithValue(ctx, "test", "World")
h.next.ServeHTTPC(ctx, w, r)
}
func main() {
c := xhandler.Chain{}
// Add close notifier handler so context is cancelled when the client closes
// the connection
c.UseC(xhandler.CloseHandler)
// Add timeout handler
c.UseC(xhandler.TimeoutHandler(2 * time.Second))
// Middleware putting something in the context
c.UseC(func(next xhandler.HandlerC) xhandler.HandlerC {
return myMiddleware{next: next}
})
// Mix it with a non-context-aware middleware handler
c.Use(cors.Default().Handler)
// Final handler (using handlerFuncC), reading from the context
xh := xhandler.HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
value := ctx.Value("test").(string)
w.Write([]byte("Hello " + value))
})
// Bridge context aware handlers with http.Handler using xhandler.Handle()
http.Handle("/test", c.Handler(xh))
if err := http.ListenAndServe(":8080", nil); err != nil {
log.Fatal(err)
}
}How to use it with a non- net/context aware router. Lets try with the Go's ServerMux:
func main() {
c := xhandler.Chain{}
// Append a context-aware middleware handler
c.UseC(xhandler.CloseHandler)
// Mix it with a non-context-aware middleware handler
c.Use(cors.Default().Handler)
// Another context-aware middleware handler
c.UseC(xhandler.TimeoutHandler(2 * time.Second))
mux := http.NewServeMux()
// Use c.Handler to terminate the chain with your final handler
mux.Handle("/", c.Handler(xhandler.HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, req *http.Request) {
fmt.Fprintf(w, "Welcome to the home page!")
})))
// You can reuse the same chain for other handlers
mux.Handle("/api", c.Handler(apiHandler))
}Here is a list of net/context aware middleware handlers implementing xhandler.HandlerC interface.
Feel free to put up a PR linking your middleware if you have built one:
| Middleware | Author | Description |
|---|---|---|
| xlog | Olivier Poitrey | HTTP handler logger |
| xstats | Olivier Poitrey | A generic client for service instrumentation |
| xaccess | Olivier Poitrey | HTTP handler access logger with xlog and xstats |
| cors | Olivier Poitrey | Cross Origin Resource Sharing (CORS) support |
All source code is licensed under the MIT License.