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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 ( | |
"io" | |
"net/http" | |
"sync/atomic" | |
) | |
func index() http.Handler { | |
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | |
if r.URL.Path != "/" { | |
http.NotFound(w, r) | |
return | |
} | |
w.Header().Set("X-Content-Type-Options", "nosniff") | |
w.Header().Set("Content-Type", "text/plain; charset=utf-8") | |
io.WriteString(w, "Hello, World!") | |
}) | |
} | |
func healthz() http.Handler { | |
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | |
if atomic.LoadInt32(&healthy) == 1 { | |
w.Header().Set("X-Content-Type-Options", "nosniff") | |
w.Header().Set("Content-Type", "application/json; charset=utf-8") | |
io.WriteString(w, `{"alive": true}`) | |
return | |
} | |
w.WriteHeader(http.StatusServiceUnavailable) | |
}) | |
} |
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package main | |
import ( | |
"fmt" | |
"log" | |
"os" | |
"time" | |
) | |
func main() { | |
listenAddr := "5000" | |
// create a logger, router and server | |
logger := log.New(os.Stdout, "http: ", log.LstdFlags) | |
router := newRouter() | |
server := newServer( | |
listenAddr, | |
(middlewares{ logging(logger), tracing(func() string { return fmt.Sprintf("%d", time.Now().UnixNano()) })}).apply(router), | |
logger, | |
) | |
// run our server | |
if err := server.run(); err != nil { | |
log.Fatal(err) | |
} | |
} |
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package main | |
import ( | |
"context" | |
"log" | |
"net/http" | |
) | |
type key int | |
const ( | |
requestIDKey key = 0 | |
) | |
type middleware func(http.Handler) http.Handler | |
type middlewares []middleware | |
func (mws middlewares) apply(hdlr http.Handler) http.Handler { | |
if len(mws) == 0 { | |
return hdlr | |
} | |
return mws[1:].apply(mws[0](hdlr)) | |
} | |
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)) | |
}) | |
} | |
} |
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package main | |
import ( | |
"net/http" | |
) | |
func newRouter() *http.ServeMux { | |
router := http.NewServeMux() | |
// routes | |
router.Handle("/", index()) | |
router.Handle("/healthz", healthz()) | |
return router | |
} |
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package main | |
import ( | |
"context" | |
"fmt" | |
"log" | |
"net/http" | |
"os" | |
"os/signal" | |
"sync/atomic" | |
"syscall" | |
"time" | |
) | |
var ( | |
healthy int32 | |
) | |
// Server implements our HTTP server | |
type Server struct { | |
server *http.Server | |
} | |
// NewServer creates a new HTTP Server | |
func newServer(port string, h http.Handler, l *log.Logger) *Server { | |
return &Server{ | |
server: &http.Server{ | |
Addr: ":" + port, | |
Handler: h, // pass in mux/router | |
ErrorLog: l, | |
ReadTimeout: 5 * time.Second, | |
WriteTimeout: 10 * time.Second, | |
IdleTimeout: 30 * time.Second, | |
MaxHeaderBytes: 1 << 20, | |
}, | |
} | |
} | |
// Run starts the HTTP server | |
func (s *Server) run() error { | |
// Get hostname | |
hostname, err := os.Hostname() | |
if err != nil { | |
return err | |
} | |
done := make(chan bool) | |
quit := make(chan os.Signal, 1) | |
signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM) | |
go func() { | |
<-quit | |
fmt.Println("") | |
s.server.ErrorLog.Printf("%s - Shutdown signal received...\n", hostname) | |
atomic.StoreInt32(&healthy, 0) | |
ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second) | |
defer cancel() | |
s.server.SetKeepAlivesEnabled(false) | |
if err := s.server.Shutdown(ctx); err != nil { | |
s.server.ErrorLog.Fatalf("Could not gracefully shutdown the server: %v\n", err) | |
} | |
close(done) | |
}() | |
s.server.ErrorLog.Printf("%s - Starting server on port %v", hostname, s.server.Addr) | |
atomic.StoreInt32(&healthy, 1) | |
if err := s.server.ListenAndServe(); err != nil && err != http.ErrServerClosed { | |
s.server.ErrorLog.Fatalf("Could not listen on %s: %v\n", s.server.Addr, err) | |
} | |
<-done | |
s.server.ErrorLog.Printf("%s - Server gracefully stopped.\n", hostname) | |
return nil | |
} |
Thanks for the catch - I changed it. ;)
Thanks for the catch - I changed it. ;)
💯 nice work
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I agree 👍