Add a unit test testing the HTTP/2 health check help the REST client

detects broken TCP connections.

Kubernetes-commit: ba7b1f7a89ffed78115ab0229b7504d05f6c7d48

Author: Chao Xu

rest/connection_test.go

@@ -0,0 +1,164 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package rest
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"os"
+	"strconv"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/runtime/serializer"
+	utilnet "k8s.io/apimachinery/pkg/util/net"
+)
+
+type tcpLB struct {
+	t         *testing.T
+	ln        net.Listener
+	serverURL string
+	dials     int32
+}
+
+func (lb *tcpLB) handleConnection(in net.Conn, stopCh chan struct{}) {
+	out, err := net.Dial("tcp", lb.serverURL)
+	if err != nil {
+		lb.t.Log(err)
+		return
+	}
+	go io.Copy(out, in)
+	go io.Copy(in, out)
+	<-stopCh
+	if err := out.Close(); err != nil {
+		lb.t.Fatalf("failed to close connection: %v", err)
+	}
+}
+
+func (lb *tcpLB) serve(stopCh chan struct{}) {
+	conn, err := lb.ln.Accept()
+	if err != nil {
+		lb.t.Fatalf("failed to accept: %v", err)
+	}
+	atomic.AddInt32(&lb.dials, 1)
+	go lb.handleConnection(conn, stopCh)
+}
+
+func newLB(t *testing.T, serverURL string) *tcpLB {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("failed to bind: %v", err)
+	}
+	lb := tcpLB{
+		serverURL: serverURL,
+		ln:        ln,
+		t:         t,
+	}
+	return &lb
+}
+
+func setEnv(key, value string) func() {
+	originalValue := os.Getenv(key)
+	os.Setenv(key, value)
+	return func() {
+		os.Setenv(key, originalValue)
+	}
+}
+
+const (
+	readIdleTimeout int = 1
+	pingTimeout     int = 1
+)
+
+func TestReconnectBrokenTCP(t *testing.T) {
+	defer setEnv("HTTP2_READ_IDLE_TIMEOUT_SECONDS", strconv.Itoa(readIdleTimeout))()
+	defer setEnv("HTTP2_PING_TIMEOUT_SECONDS", strconv.Itoa(pingTimeout))()
+	defer setEnv("DISABLE_HTTP2", "")()
+	ts := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, "Hello, %s", r.Proto)
+	}))
+	ts.EnableHTTP2 = true
+	ts.StartTLS()
+	defer ts.Close()
+
+	u, err := url.Parse(ts.URL)
+	if err != nil {
+		t.Fatalf("failed to parse URL from %q: %v", ts.URL, err)
+	}
+	lb := newLB(t, u.Host)
+	defer lb.ln.Close()
+	stopCh := make(chan struct{})
+	go lb.serve(stopCh)
+	transport, ok := ts.Client().Transport.(*http.Transport)
+	if !ok {
+		t.Fatalf("failed to assert *http.Transport")
+	}
+	config := &Config{
+		Host:      "https://" + lb.ln.Addr().String(),
+		Transport: utilnet.SetTransportDefaults(transport),
+		Timeout:   1 * time.Second,
+		// These fields are required to create a REST client.
+		ContentConfig: ContentConfig{
+			GroupVersion:         &schema.GroupVersion{},
+			NegotiatedSerializer: &serializer.CodecFactory{},
+		},
+	}
+	client, err := RESTClientFor(config)
+	if err != nil {
+		t.Fatalf("failed to create REST client: %v", err)
+	}
+	data, err := client.Get().AbsPath("/").DoRaw(context.TODO())
+	if err != nil {
+		t.Fatalf("unexpected err: %s: %v", data, err)
+	}
+	if string(data) != "Hello, HTTP/2.0" {
+		t.Fatalf("unexpected response: %s", data)
+	}
+
+	// Deliberately let the LB stop proxying traffic for the current
+	// connection. This mimics a broken TCP connection that's not properly
+	// closed.
+	close(stopCh)
+
+	stopCh = make(chan struct{})
+	go lb.serve(stopCh)
+	// Sleep enough time for the HTTP/2 health check to detect and close
+	// the broken TCP connection.
+	time.Sleep(time.Duration(1+readIdleTimeout+pingTimeout) * time.Second)
+	// If the HTTP/2 health check were disabled, the broken connection
+	// would still be in the connection pool, the following request would
+	// then reuse the broken connection instead of creating a new one, and
+	// thus would fail.
+	data, err = client.Get().AbsPath("/").DoRaw(context.TODO())
+	if err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	if string(data) != "Hello, HTTP/2.0" {
+		t.Fatalf("unexpected response: %s", data)
+	}
+	dials := atomic.LoadInt32(&lb.dials)
+	if dials != 2 {
+		t.Fatalf("expected %d dials, got %d", 2, dials)
+	}
+}