add goa examples

go/goa_example/cmd/host/http.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"context"
+	petstoresvr "goa_example/gen/http/pet_store/server"
+	petstore "goa_example/gen/pet_store"
+	"log"
+	"net/http"
+	"net/url"
+	"os"
+	"sync"
+	"time"
+
+	goahttp "goa.design/goa/v3/http"
+	httpmdlwr "goa.design/goa/v3/http/middleware"
+	"goa.design/goa/v3/middleware"
+)
+
+// handleHTTPServer starts configures and starts a HTTP server on the given
+// URL. It shuts down the server if any error is received in the error channel.
+func handleHTTPServer(ctx context.Context, u *url.URL, petStoreEndpoints *petstore.Endpoints, wg *sync.WaitGroup, errc chan error, logger *log.Logger, debug bool) {
+
+	// Setup goa log adapter.
+	var (
+		adapter middleware.Logger
+	)
+	{
+		adapter = middleware.NewLogger(logger)
+	}
+
+	// Provide the transport specific request decoder and response encoder.
+	// The goa http package has built-in support for JSON, XML and gob.
+	// Other encodings can be used by providing the corresponding functions,
+	// see goa.design/implement/encoding.
+	var (
+		dec = goahttp.RequestDecoder
+		enc = goahttp.ResponseEncoder
+	)
+
+	// Build the service HTTP request multiplexer and configure it to serve
+	// HTTP requests to the service endpoints.
+	var mux goahttp.Muxer
+	{
+		mux = goahttp.NewMuxer()
+	}
+
+	// Wrap the endpoints with the transport specific layers. The generated
+	// server packages contains code generated from the design which maps
+	// the service input and output data structures to HTTP requests and
+	// responses.
+	var (
+		petStoreServer *petstoresvr.Server
+	)
+	{
+		eh := errorHandler(logger)
+		petStoreServer = petstoresvr.New(petStoreEndpoints, mux, dec, enc, eh, nil)
+		if debug {
+			servers := goahttp.Servers{
+				petStoreServer,
+			}
+			servers.Use(httpmdlwr.Debug(mux, os.Stdout))
+		}
+	}
+	// Configure the mux.
+	petstoresvr.Mount(mux, petStoreServer)
+
+	// Wrap the multiplexer with additional middlewares. Middlewares mounted
+	// here apply to all the service endpoints.
+	var handler http.Handler = mux
+	{
+		handler = httpmdlwr.Log(adapter)(handler)
+		handler = httpmdlwr.RequestID()(handler)
+	}
+
+	// Start HTTP server using default configuration, change the code to
+	// configure the server as required by your service.
+	srv := &http.Server{Addr: u.Host, Handler: handler}
+	for _, m := range petStoreServer.Mounts {
+		logger.Printf("HTTP %q mounted on %s %s", m.Method, m.Verb, m.Pattern)
+	}
+
+	(*wg).Add(1)
+	go func() {
+		defer (*wg).Done()
+
+		// Start HTTP server in a separate goroutine.
+		go func() {
+			logger.Printf("HTTP server listening on %q", u.Host)
+			errc <- srv.ListenAndServe()
+		}()
+
+		<-ctx.Done()
+		logger.Printf("shutting down HTTP server at %q", u.Host)
+
+		// Shutdown gracefully with a 30s timeout.
+		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+		defer cancel()
+
+		_ = srv.Shutdown(ctx)
+	}()
+}
+
+// errorHandler returns a function that writes and logs the given error.
+// The function also writes and logs the error unique ID so that it's possible
+// to correlate.
+func errorHandler(logger *log.Logger) func(context.Context, http.ResponseWriter, error) {
+	return func(ctx context.Context, w http.ResponseWriter, err error) {
+		id := ctx.Value(middleware.RequestIDKey).(string)
+		_, _ = w.Write([]byte("[" + id + "] encoding: " + err.Error()))
+		logger.Printf("[%s] ERROR: %s", id, err.Error())
+	}
+}