Use common httpserver across fission (#2409)

* Defining httpserver package to capture httpserver shutdown and
introduces uniform running of http server across codebase.
* Add unit tests for httpserver

Signed-off-by: Sanket Sudake <sanketsudake@gmail.com>

pkg/utils/httpserver/server.go

@@ -0,0 +1,32 @@
+package httpserver
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	"go.uber.org/zap"
+)
+
+func StartServer(ctx context.Context, log *zap.Logger, svc string, port string, handler http.Handler) {
+	server := http.Server{
+		Addr:    fmt.Sprintf(":%s", port),
+		Handler: handler,
+	}
+	l := log.With(zap.String("service", svc), zap.String("addr", server.Addr))
+	l.Info("starting server")
+	go func() {
+		if err := server.ListenAndServe(); err != nil {
+			if err != http.ErrServerClosed {
+				l.Error("server error", zap.Error(err))
+			}
+		}
+	}()
+	<-ctx.Done()
+	l.Info("shutting down server")
+	if err := server.Shutdown(ctx); err != nil {
+		if err != context.Canceled && err != context.DeadlineExceeded {
+			l.Error("server shutdown error", zap.Error(err))
+		}
+	}
+}

pkg/utils/httpserver/server_test.go

@@ -0,0 +1,62 @@
+package httpserver
+
+import (
+	"context"
+	"io/ioutil"
+	"net/http"
+	"testing"
+
+	"github.com/gorilla/mux"
+	"go.uber.org/zap"
+
+	"github.com/fission/fission/pkg/utils/loggerfactory"
+)
+
+func TestStartServer(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	logger := loggerfactory.GetLogger()
+	m := mux.NewRouter()
+	m.Handle("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		_, err := w.Write([]byte("test handler"))
+		if err != nil {
+			logger.Error("failed to write response", zap.Error(err))
+		}
+	}))
+	go StartServer(ctx, logger, "test", "8999", m)
+
+	tests := []struct {
+		URL        string
+		StatusCode int
+		Body       string
+	}{
+		{
+			URL:        "http://localhost:8999",
+			StatusCode: http.StatusOK,
+			Body:       "test handler",
+		},
+		{
+			URL:        "http://localhost:8999/notfound",
+			StatusCode: http.StatusNotFound,
+			Body:       "404 page not found\n",
+		},
+	}
+	for _, test := range tests {
+		resp, err := http.Get(test.URL)
+		if err != nil {
+			t.Errorf("failed to make get request %v: %v", test.URL, err)
+		}
+		defer resp.Body.Close()
+		if resp.StatusCode != test.StatusCode {
+			t.Errorf("expected status code %v, got %v", test.StatusCode, resp.StatusCode)
+		}
+		body, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			t.Errorf("failed to read response body: %v", err)
+		}
+		if string(body) != test.Body {
+			t.Errorf("expected body \"%v\", got \"%v\"", test.Body, string(body))
+		}
+	}
+}

pkg/utils/metrics/server.go

@@ -23,34 +23,16 @@ import (
 
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"go.uber.org/zap"
+
+	"github.com/fission/fission/pkg/utils/httpserver"
 )
 
 func ServeMetrics(ctx context.Context, logger *zap.Logger) {
 	metricsAddr := os.Getenv("METRICS_ADDR")
 	if metricsAddr == "" {
-		metricsAddr = ":8080"
+		metricsAddr = "8080"
 	}
 	mux := http.NewServeMux()
 	mux.Handle("/metrics", promhttp.Handler())
-	s := &http.Server{
-		Addr:    metricsAddr,
-		Handler: mux,
-	}
-	logger.Info("Starting metrics server", zap.String("address", metricsAddr))
-	go func() {
-		if err := s.ListenAndServe(); err != nil {
-			if err != http.ErrServerClosed {
-				logger.Error("Metrics server error", zap.Error(err))
-			}
-		}
-	}()
-	<-ctx.Done()
-	logger.Info("Shutting down metrics server")
-	err := s.Shutdown(ctx)
-	if err == context.DeadlineExceeded || err == context.Canceled {
-		return
-	}
-	if err != nil {
-		logger.Error("Failed to shutdown metrics server", zap.Error(err))
-	}
+	httpserver.StartServer(ctx, logger, "metrics", metricsAddr, mux)
 }

pkg/utils/profile/profile.go

@@ -24,12 +24,15 @@ limitations under the License.
 package profile
 
 import (
+	"context"
 	"fmt"
 	"net/http"
 	_ "net/http/pprof"
 	"os"
 
 	"go.uber.org/zap"
+
+	"github.com/fission/fission/pkg/utils/httpserver"
 )
 
 func getPprofAddr() string {
@@ -44,7 +47,7 @@ func getPprofAddr() string {
 	return fmt.Sprintf("%s:%s", pprofHost, pprofPort)
 }
 
-func ProfileIfEnabled(logger *zap.Logger) {
+func ProfileIfEnabled(ctx context.Context, logger *zap.Logger) {
 	enablePprof := os.Getenv("PPROF_ENABLED")
 	if enablePprof != "true" {
 		return
@@ -53,12 +56,5 @@ func ProfileIfEnabled(logger *zap.Logger) {
 	pprofMux := http.DefaultServeMux
 	http.DefaultServeMux = http.NewServeMux()
 
-	addr := getPprofAddr()
-	logger.Info("Running pprof server", zap.String("addr", addr))
-	go func() {
-		err := http.ListenAndServe(addr, pprofMux)
-		if err != nil {
-			logger.Fatal("pprof http server failed", zap.Error(err))
-		}
-	}()
+	go httpserver.StartServer(ctx, logger, "pprof", getPprofAddr(), pprofMux)
 }