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A simple golang web server with basic logging, tracing, health check, graceful shutdown and zero dependencies
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package main | |
import ( | |
"context" | |
"flag" | |
"fmt" | |
"log" | |
"net/http" | |
"os" | |
"os/signal" | |
"sync/atomic" | |
"time" | |
) | |
type key int | |
const ( | |
requestIDKey key = 0 | |
) | |
var ( | |
listenAddr string | |
healthy int32 | |
) | |
func main() { | |
flag.StringVar(&listenAddr, "listen-addr", ":5000", "server listen address") | |
flag.Parse() | |
logger := log.New(os.Stdout, "http: ", log.LstdFlags) | |
logger.Println("Server is starting...") | |
router := http.NewServeMux() | |
router.Handle("/", index()) | |
router.Handle("/healthz", healthz()) | |
nextRequestID := func() string { | |
return fmt.Sprintf("%d", time.Now().UnixNano()) | |
} | |
server := &http.Server{ | |
Addr: listenAddr, | |
Handler: tracing(nextRequestID)(logging(logger)(router)), | |
ErrorLog: logger, | |
ReadTimeout: 5 * time.Second, | |
WriteTimeout: 10 * time.Second, | |
IdleTimeout: 15 * time.Second, | |
} | |
done := make(chan bool) | |
quit := make(chan os.Signal, 1) | |
signal.Notify(quit, os.Interrupt) | |
go func() { | |
<-quit | |
logger.Println("Server is shutting down...") | |
atomic.StoreInt32(&healthy, 0) | |
ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second) | |
defer cancel() | |
server.SetKeepAlivesEnabled(false) | |
if err := server.Shutdown(ctx); err != nil { | |
logger.Fatalf("Could not gracefully shutdown the server: %v\n", err) | |
} | |
close(done) | |
}() | |
logger.Println("Server is ready to handle requests at", listenAddr) | |
atomic.StoreInt32(&healthy, 1) | |
if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed { | |
logger.Fatalf("Could not listen on %s: %v\n", listenAddr, err) | |
} | |
<-done | |
logger.Println("Server stopped") | |
} | |
func index() http.Handler { | |
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | |
if r.URL.Path != "/" { | |
http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound) | |
return | |
} | |
w.Header().Set("Content-Type", "text/plain; charset=utf-8") | |
w.Header().Set("X-Content-Type-Options", "nosniff") | |
w.WriteHeader(http.StatusOK) | |
fmt.Fprintln(w, "Hello, World!") | |
}) | |
} | |
func healthz() http.Handler { | |
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | |
if atomic.LoadInt32(&healthy) == 1 { | |
w.WriteHeader(http.StatusNoContent) | |
return | |
} | |
w.WriteHeader(http.StatusServiceUnavailable) | |
}) | |
} | |
func logging(logger *log.Logger) func(http.Handler) http.Handler { | |
return func(next http.Handler) http.Handler { | |
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | |
defer func() { | |
requestID, ok := r.Context().Value(requestIDKey).(string) | |
if !ok { | |
requestID = "unknown" | |
} | |
logger.Println(requestID, r.Method, r.URL.Path, r.RemoteAddr, r.UserAgent()) | |
}() | |
next.ServeHTTP(w, r) | |
}) | |
} | |
} | |
func tracing(nextRequestID func() string) func(http.Handler) http.Handler { | |
return func(next http.Handler) http.Handler { | |
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | |
requestID := r.Header.Get("X-Request-Id") | |
if requestID == "" { | |
requestID = nextRequestID() | |
} | |
ctx := context.WithValue(r.Context(), requestIDKey, requestID) | |
w.Header().Set("X-Request-Id", requestID) | |
next.ServeHTTP(w, r.WithContext(ctx)) | |
}) | |
} | |
} |
Thanks for sharing
I'd like to use this code in an open source static site generator. It's MIT licensed. Can I use this code, or at least a version of it? And if so, what's your license for it? Thanks!
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Any pointers on how to include the http.statuscode in logs, please?