proxy: should add PingPeriod for websocket translator

IIUC, before using the translator handler, the ping data can be delivered from
the client to the runtime side since kube-apiserver does not parse any client
data. However, with WebSocket, the server responds with a pong to the client
without forwarding the data to the runtime side. If a proxy is present, it may
close the connection due to inactivity. SPDY's PingPeriod can help address this
issue.

Signed-off-by: Wei Fu <[email protected]>
Co-authored-by: Antonio Ojea <[email protected]>

Author: fuweid

staging/src/k8s.io/apiserver/pkg/util/proxy/streamtranslator.go

@@ -21,6 +21,7 @@ import (
 	"net/http"
 	"net/url"
 	"strconv"
+	"time"
 
 	"github.com/mxk/go-flowrate/flowrate"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
@@ -70,7 +71,7 @@ func (h *StreamTranslatorHandler) ServeHTTP(w http.ResponseWriter, req *http.Req
 	defer websocketStreams.conn.Close()
 
 	// Creating SPDY executor, ensuring redirects are not followed.
-	spdyRoundTripper, err := spdy.NewRoundTripperWithConfig(spdy.RoundTripperConfig{UpgradeTransport: h.Transport})
+	spdyRoundTripper, err := spdy.NewRoundTripperWithConfig(spdy.RoundTripperConfig{UpgradeTransport: h.Transport, PingPeriod: 5 * time.Second})
 	if err != nil {
 		websocketStreams.writeStatus(apierrors.NewInternalError(err)) //nolint:errcheck
 		metrics.IncStreamTranslatorRequest(req.Context(), strconv.Itoa(http.StatusInternalServerError))

test/e2e/kubectl/kubectl.go

@@ -501,6 +501,16 @@ var _ = SIGDescribe("Kubectl client", func() {
 			}
 		})
 
+		// https://issues.k8s.io/128314
+		f.It(f.WithSlow(), "should support exec idle connections", func(ctx context.Context) {
+			ginkgo.By("executing a command in the container")
+
+			execOutput := e2ekubectl.RunKubectlOrDie(ns, "exec", podRunningTimeoutArg, simplePodName, "--", "/bin/sh", "-c", "sleep 320 && echo running in container")
+			if expected, got := "running in container", strings.TrimSpace(execOutput); expected != got {
+				framework.Failf("Unexpected kubectl exec output. Wanted %q, got %q", expected, got)
+			}
+		})
+
 		ginkgo.It("should support exec through kubectl proxy", func(ctx context.Context) {
 			_ = getTestContextHost()