Don't log "expected" websocket errors

app/api_topology.go

@@ -90,7 +90,9 @@ func handleWebsocket(
 	go func(c *websocket.Conn) {
 		for { // just discard everything the browser sends
 			if _, _, err := c.NextReader(); err != nil {
-				log.Println("err:", err)
+				if !xfer.IsExpectedWSCloseError(err) {
+					log.Println("err:", err)
+				}
 				close(quit)
 				break
 			}
@@ -111,7 +113,9 @@ func handleWebsocket(
 		previousTopo = newTopo
 
 		if err := conn.SetWriteDeadline(time.Now().Add(websocketTimeout)); err != nil {
-			log.Println("err:", err)
+			if !xfer.IsExpectedWSCloseError(err) {
+				log.Println("err:", err)
+			}
 			return
 		}
 

app/controls.go

@@ -79,6 +79,8 @@ func handleProbeWS(cr ControlRouter) CtxHandlerFunc {
 			return
 		}
 		defer cr.Deregister(ctx, probeID, id)
-		codec.WaitForReadError()
+		if err := codec.WaitForReadError(); err != nil && !xfer.IsExpectedWSCloseError(err) {
+			log.Printf("Error reading from probe %s control websocket: %v", probeID, err)
+		}
 	}
 }

app/pipes.go

@@ -6,6 +6,8 @@ import (
 	log "github.com/Sirupsen/logrus"
 	"github.com/gorilla/mux"
 	"golang.org/x/net/context"
+
+	"github.com/weaveworks/scope/common/xfer"
 )
 
 // RegisterPipeRoutes registers the pipe routes
@@ -41,7 +43,9 @@ func handlePipeWs(pr PipeRouter, end End) CtxHandlerFunc {
 		defer conn.Close()
 
 		log.Infof("Pipe success %s (%d)", id, end)
-		pipe.CopyToWebsocket(endIO, conn)
+		if err := pipe.CopyToWebsocket(endIO, conn); err != nil && !xfer.IsExpectedWSCloseError(err) {
+			log.Printf("Error copying to pipe %s (%d) websocket: %v", id, end, err)
+		}
 	}
 }
 

common/xfer/controls.go

@@ -71,21 +71,21 @@ func ResponseError(err error) Response {
 type JSONWebsocketCodec struct {
 	sync.Mutex
 	conn *websocket.Conn
-	err  chan struct{}
+	err  chan error
 }
 
 // NewJSONWebsocketCodec makes a new JSONWebsocketCodec
 func NewJSONWebsocketCodec(conn *websocket.Conn) *JSONWebsocketCodec {
 	return &JSONWebsocketCodec{
 		conn: conn,
-		err:  make(chan struct{}),
+		err:  make(chan error, 1),
 	}
 }
 
 // WaitForReadError blocks until any read on this codec returns an error.
 // This is useful to know when the server has disconnected from the client.
-func (j *JSONWebsocketCodec) WaitForReadError() {
-	<-j.err
+func (j *JSONWebsocketCodec) WaitForReadError() error {
+	return <-j.err
 }
 
 // WriteRequest implements rpc.ClientCodec
@@ -113,6 +113,7 @@ func (j *JSONWebsocketCodec) WriteResponse(r *rpc.Response, v interface{}) error
 func (j *JSONWebsocketCodec) readMessage(v interface{}) (*Message, error) {
 	m := Message{Value: v}
 	if err := ReadJSONfromWS(j.conn, &m); err != nil {
+		j.err <- err
 		close(j.err)
 		return nil, err
 	}

common/xfer/websocket.go

@@ -7,6 +7,17 @@ import (
 	"github.com/ugorji/go/codec"
 )
 
+// IsExpectedWSCloseError returns boolean indicating whether the error is a
+// clean disconnection.
+func IsExpectedWSCloseError(err error) bool {
+	return websocket.IsCloseError(
+		err,
+		websocket.CloseNormalClosure,
+		websocket.CloseGoingAway,
+		websocket.CloseNoStatusReceived,
+	)
+}
+
 // WriteJSONtoWS writes the JSON encoding of v to the connection.
 func WriteJSONtoWS(c *websocket.Conn, v interface{}) error {
 	w, err := c.NextWriter(websocket.TextMessage)