Correctly send close message when closing websocket connection

Signed-off-by: Maya Rosecrance <mrosecrance@pivotal.io>

server/handlers/websocket_handler.go

@@ -29,7 +29,7 @@ func (h *websocketHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 		return
 	}
 	defer ws.Close()
-	defer ws.WriteControl(websocket.CloseMessage, []byte{}, time.Time{})
+	defer ws.WriteControl(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""), time.Time{})
 	keepAliveExpired := make(chan struct{})
 
 	// TODO: remove this loop (but keep ws.ReadMessage()) once we retire support in the cli for old style keep alives

server/handlers/websocket_handler_test.go

@@ -4,11 +4,13 @@ import (
 	"github.com/cloudfoundry/loggregatorlib/loggertesthelper"
 	"github.com/cloudfoundry/loggregatorlib/server/handlers"
 	"github.com/gorilla/websocket"
-	. "github.com/onsi/ginkgo"
-	. "github.com/onsi/gomega"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"time"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
 )
 
 var _ = Describe("WebsocketHandler", func() {
@@ -118,6 +120,14 @@ var _ = Describe("WebsocketHandler", func() {
 		close(messagesChan)
 	})
 
+	It("should send a closing message", func() {
+		ws, _, err := websocket.DefaultDialer.Dial(httpToWs(testServer.URL), nil)
+		Expect(err).NotTo(HaveOccurred())
+		close(messagesChan)
+		_, _, err = ws.ReadMessage()
+		Expect(err).To(Equal(io.EOF))
+	})
+
 })
 
 func httpToWs(u string) string {