add existing http health check handler e2e test

Signed-off-by: Chao Chen <chaochn@amazon.com>

server/etcdserver/server.go

@@ -1822,6 +1822,7 @@ func (s *EtcdServer) apply(
 			zap.Stringer("type", e.Type))
 		switch e.Type {
 		case raftpb.EntryNormal:
+			// gofail: var beforeApplyOneEntryNormal struct{}
 			s.applyEntryNormal(&e)
 			s.setAppliedIndex(e.Index)
 			s.setTerm(e.Term)

tests/e2e/http_health_check_test.go

@@ -0,0 +1,229 @@
+// Copyright 2023 The etcd 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.
+
+//go:build !cluster_proxy
+
+package e2e
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"go.etcd.io/etcd/tests/v3/framework/config"
+	"go.etcd.io/etcd/tests/v3/framework/e2e"
+	"go.etcd.io/etcd/tests/v3/framework/testutils"
+)
+
+type healthCheckConfig struct {
+	url                  string
+	expectedStatusCode   int
+	expectedTimeoutError bool
+}
+
+func TestHTTPHealthHandler(t *testing.T) {
+	e2e.BeforeTest(t)
+	client := &http.Client{}
+	tcs := []struct {
+		name           string
+		injectFailure  func(ctx context.Context, t *testing.T, clus *e2e.EtcdProcessCluster)
+		clusterOptions []e2e.EPClusterOption
+		healthChecks   []healthCheckConfig
+	}{
+		{
+			name:           "no failures", // happy case
+			clusterOptions: []e2e.EPClusterOption{e2e.WithClusterSize(1)},
+			healthChecks: []healthCheckConfig{
+				{
+					url:                "/health",
+					expectedStatusCode: http.StatusOK,
+				},
+			},
+		},
+		{
+			name:           "activated no space alarm",
+			injectFailure:  triggerNoSpaceAlarm,
+			clusterOptions: []e2e.EPClusterOption{e2e.WithClusterSize(1), e2e.WithQuotaBackendBytes(int64(13 * os.Getpagesize()))},
+			healthChecks: []healthCheckConfig{
+				{
+					url:                "/health",
+					expectedStatusCode: http.StatusServiceUnavailable,
+				},
+				{
+					url:                "/health?exclude=NOSPACE",
+					expectedStatusCode: http.StatusOK,
+				},
+			},
+		},
+		{
+			name:           "overloaded server slow apply",
+			injectFailure:  triggerSlowApply,
+			clusterOptions: []e2e.EPClusterOption{e2e.WithClusterSize(3), e2e.WithGoFailEnabled(true)},
+			healthChecks: []healthCheckConfig{
+				{
+					url:                "/health?serializable=true",
+					expectedStatusCode: http.StatusOK,
+				},
+				{
+					url:                  "/health?serializable=false",
+					expectedTimeoutError: true,
+				},
+			},
+		},
+		{
+			name:           "network partitioned",
+			injectFailure:  blackhole,
+			clusterOptions: []e2e.EPClusterOption{e2e.WithClusterSize(3), e2e.WithIsPeerTLS(true), e2e.WithPeerProxy(true)},
+			healthChecks: []healthCheckConfig{
+				{
+					url:                "/health?serializable=true",
+					expectedStatusCode: http.StatusOK,
+				},
+				{
+					url:                  "/health?serializable=false",
+					expectedTimeoutError: true,
+					expectedStatusCode:   http.StatusServiceUnavailable,
+					// old leader may return "etcdserver: leader changed" error with 503 in ReadIndex leaderChangedNotifier
+				},
+			},
+		},
+		{
+			name:           "raft loop deadlock",
+			injectFailure:  triggerRaftLoopDeadLock,
+			clusterOptions: []e2e.EPClusterOption{e2e.WithClusterSize(1), e2e.WithGoFailEnabled(true)},
+			healthChecks: []healthCheckConfig{
+				{
+					// current kubeadm etcd liveness check failed to detect raft loop deadlock in steady state
+					// ref. https://github.com/kubernetes/kubernetes/blob/master/cmd/kubeadm/app/phases/etcd/local.go#L225-L226
+					// current liveness probe depends on the etcd /health check has a flaw that new /livez check should resolve.
+					url:                "/health?serializable=true",
+					expectedStatusCode: http.StatusOK,
+				},
+				{
+					url:                  "/health?serializable=false",
+					expectedTimeoutError: true,
+				},
+			},
+		},
+		// verify that auth enabled serializable read must go through mvcc
+		// this test case is skipped until https://github.com/etcd-io/etcd/pull/16697 is merged.
+		{
+			name:           "slow buffer write back with auth enabled",
+			injectFailure:  triggerSlowBufferWriteBackWithAuth,
+			clusterOptions: []e2e.EPClusterOption{e2e.WithClusterSize(1), e2e.WithGoFailEnabled(true)},
+			healthChecks: []healthCheckConfig{
+				{
+					url:                  "/health?serializable=true",
+					expectedTimeoutError: true,
+				},
+			},
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
+			defer cancel()
+			clus, err := e2e.NewEtcdProcessCluster(ctx, t, tc.clusterOptions...)
+			require.NoError(t, err)
+			defer clus.Close()
+			testutils.ExecuteUntil(ctx, t, func() {
+				if tc.injectFailure != nil {
+					tc.injectFailure(ctx, t, clus)
+				}
+
+				for _, hc := range tc.healthChecks {
+					requestURL := clus.Procs[0].EndpointsHTTP()[0] + hc.url
+					t.Logf("health check URL is %s", requestURL)
+					doHealthCheckAndVerify(t, client, requestURL, hc.expectedStatusCode, hc.expectedTimeoutError)
+				}
+			})
+		})
+	}
+}
+
+func doHealthCheckAndVerify(t *testing.T, client *http.Client, url string, expectStatusCode int, expectTimeoutError bool) {
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+	require.NoErrorf(t, err, "failed to creat request %+v", err)
+	resp, herr := client.Do(req)
+	cancel()
+	if expectTimeoutError {
+		if herr != nil && herr.Error() == context.DeadlineExceeded.Error() {
+			return
+		}
+	}
+	require.NoErrorf(t, herr, "failed to get response %+v", err)
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	resp.Body.Close()
+	require.NoErrorf(t, err, "failed to read response %+v", err)
+
+	t.Logf("health check response body is: %s", body)
+	require.Equal(t, expectStatusCode, resp.StatusCode)
+}
+
+func triggerNoSpaceAlarm(ctx context.Context, t *testing.T, clus *e2e.EtcdProcessCluster) {
+	buf := strings.Repeat("b", os.Getpagesize())
+	etcdctl := clus.Etcdctl()
+	for {
+		if err := etcdctl.Put(ctx, "foo", buf, config.PutOptions{}); err != nil {
+			if !strings.Contains(err.Error(), "etcdserver: mvcc: database space exceeded") {
+				t.Fatal(err)
+			}
+			break
+		}
+	}
+}
+
+func triggerSlowApply(ctx context.Context, t *testing.T, clus *e2e.EtcdProcessCluster) {
+	// the following proposal will be blocked at applying stage
+	// because when apply index < committed index, linearizable read would time out.
+	require.NoError(t, clus.Procs[0].Failpoints().SetupHTTP(ctx, "beforeApplyOneEntryNormal", `sleep("3s")`))
+	require.NoError(t, clus.Procs[1].Etcdctl().Put(ctx, "foo", "bar", config.PutOptions{}))
+}
+
+func blackhole(_ context.Context, t *testing.T, clus *e2e.EtcdProcessCluster) {
+	member := clus.Procs[0]
+	proxy := member.PeerProxy()
+	t.Logf("Blackholing traffic from and to member %q", member.Config().Name)
+	proxy.BlackholeTx()
+	proxy.BlackholeRx()
+}
+
+func triggerRaftLoopDeadLock(ctx context.Context, t *testing.T, clus *e2e.EtcdProcessCluster) {
+	err := clus.Procs[0].Failpoints().SetupHTTP(ctx, "raftBeforeSave", `sleep("3s")`)
+	require.NoError(t, err)
+	clus.Procs[0].Etcdctl().Put(context.Background(), "foo", "bar", config.PutOptions{})
+}
+
+func triggerSlowBufferWriteBackWithAuth(ctx context.Context, t *testing.T, clus *e2e.EtcdProcessCluster) {
+	t.Skip("wait until https://github.com/etcd-io/etcd/pull/16697 merged that using root permissions doing serializable read")
+	etcdctl := clus.Etcdctl()
+	_, err := etcdctl.UserAdd(ctx, "root", "root", config.UserAddOptions{})
+	require.NoError(t, err)
+	_, err = etcdctl.UserGrantRole(ctx, "root", "root")
+	require.NoError(t, err)
+	require.NoError(t, etcdctl.AuthEnable(ctx))
+
+	require.NoError(t, clus.Procs[0].Failpoints().SetupHTTP(ctx, "beforeWritebackBuf", `sleep("3s")`))
+	clus.Procs[0].Etcdctl(e2e.WithAuth("root", "root")).Put(context.Background(), "foo", "bar", config.PutOptions{Timeout: 200 * time.Millisecond})
+}

tests/framework/config/client.go

@@ -42,6 +42,7 @@ type GetOptions struct {
 
 type PutOptions struct {
 	LeaseID clientv3.LeaseID
+	Timeout time.Duration
 }
 
 type DeleteOptions struct {

tests/framework/e2e/etcdctl.go

@@ -158,6 +158,9 @@ func (ctl *EtcdctlV3) Put(ctx context.Context, key, value string, opts config.Pu
 	if opts.LeaseID != 0 {
 		args = append(args, "--lease", strconv.FormatInt(int64(opts.LeaseID), 16))
 	}
+	if opts.Timeout != 0 {
+		args = append(args, fmt.Sprintf("--command-timeout=%s", opts.Timeout))
+	}
 	_, err := SpawnWithExpectLines(ctx, args, nil, expect.ExpectedResponse{Value: "OK"})
 	return err
 }

tests/framework/integration/integration.go

@@ -169,6 +169,11 @@ func (c integrationClient) Get(ctx context.Context, key string, o config.GetOpti
 }
 
 func (c integrationClient) Put(ctx context.Context, key, value string, opts config.PutOptions) error {
+	if opts.Timeout != 0 {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, opts.Timeout)
+		defer cancel()
+	}
 	var clientOpts []clientv3.OpOption
 	if opts.LeaseID != 0 {
 		clientOpts = append(clientOpts, clientv3.WithLease(opts.LeaseID))