Support slow log tailing sidcar for tidb instance (pingcap#290)

* Support slow log tailing sidcar for tidb instance

charts/tidb-cluster/templates/scripts/_start_tidb.sh.tpl

@@ -34,6 +34,11 @@ then
     ARGS="${ARGS} --enable-binlog=true"
 fi
 
+if [[ ! -z "${SLOW_LOG_FILE}" ]]
+then
+    ARGS="${ARGS} --log-slow-query=${SLOW_LOG_FILE:-}"
+fi
+
 echo "start tidb-server ..."
 echo "/tidb-server ${ARGS}"
 exec /tidb-server ${ARGS}

charts/tidb-cluster/templates/tidb-cluster.yaml

@@ -76,3 +76,10 @@ spec:
   {{- end }}
     binlogEnabled: {{ .Values.binlog.pump.create | default false }}
     maxFailoverCount: {{ .Values.tidb.maxFailoverCount | default 3 }}
+    separateSlowLog: {{ .Values.tidb.separateSlowLog | default false }}
+    slowLogTailer:
+      image: {{ .Values.tidb.slowLogTailer.image }}
+      imagePullPolicy: {{ .Values.tidb.slowLogTailer.imagePullPolicy | default "IfNotPresent" }}
+      {{- if .Values.tidb.slowLogTailer.resources }}
+{{ toYaml .Values.tidb.slowLogTailer.resources | indent 6 }}
+      {{- end }}

charts/tidb-cluster/values.yaml

@@ -175,6 +175,16 @@ tidb:
     exposeStatus: true
     # annotations:
       # cloud.google.com/load-balancer-type: Internal
+  # separateSlowLog: true
+  slowLogTailer:
+    image: busybox:1.26.2
+    resources:
+      limits:
+        cpu: 100m
+        memory: 50Mi
+      requests:
+        cpu: 20m
+        memory: 5Mi
 
 # mysqlClient is used to set password for TiDB
 mysqlClient:

docs/operation-guide.md

@@ -131,6 +131,33 @@ Then open your browser at http://localhost:3000 The default username and passwor
 
 The Grafana service is exposed as `NodePort` by default, you can change it to `LoadBalancer` if the underlining Kubernetes has load balancer support. And then view the dashboard via load balancer endpoint.
 
+### View TiDB Slow Query Log
+
+For default setup, tidb is configured to export slow query log to STDOUT along with normal server logs. You can obtain the slow query log by `grep` the keyword `SLOW_QUERY`:
+
+```shell
+$ kubectl logs -n ${namespace} ${tidbPodName} | grep SLOW_QUERY
+```
+
+Optionally, you can output slow query log in a separate sidecar by enabling `separateSlowLog`:
+
+```yaml
+# Uncomment the following line to enable separate output of the slow query log
+    # separateSlowLog: true
+```
+
+Run `helm upgrade` to apply the change, then you can obtain the slow query log from the sidecar named `slowlog`:
+
+```shell
+$ kubectl logs -n ${namespace} ${tidbPodName} -c slowlog
+```
+
+To retrieve logs from multiple pods, [`stern`](https://github.com/wercker/stern) is recommended.
+
+```shell
+$ stern -n ${namespace} tidb -c slowlog
+```
+
 ## Backup
 
 Currently, TiDB Operator supports two kinds of backup: incremental backup via binlog and full backup(scheduled or ad-hoc) via [Mydumper](https://github.com/maxbube/mydumper).

images/tidb-operator-e2e/tidb-cluster-values.yaml

@@ -143,6 +143,7 @@ tidb:
     exposeStatus: true
     # annotations:
       # cloud.google.com/load-balancer-type: Internal
+  separateSlowLog: true
 
 # mysqlClient is used to set password for TiDB
 mysqlClient:

pkg/apis/pingcap.com/v1alpha1/types.go

@@ -42,8 +42,10 @@ const (
 	TiDBMemberType MemberType = "tidb"
 	// TiKVMemberType is tikv container type
 	TiKVMemberType MemberType = "tikv"
-	//PushGatewayMemberType is pushgateway container type
+	// PushGatewayMemberType is pushgateway container type
 	PushGatewayMemberType MemberType = "pushgateway"
+	// SlowLogTailerMemberType is tidb log tailer container type
+	SlowLogTailerMemberType MemberType = "slowlog"
 	// UnknownMemberType is unknown container type
 	UnknownMemberType MemberType = "unknown"
 )
@@ -117,13 +119,20 @@ type PDSpec struct {
 // TiDBSpec contains details of PD member
 type TiDBSpec struct {
 	ContainerSpec
-	Replicas             int32               `json:"replicas"`
-	NodeSelector         map[string]string   `json:"nodeSelector,omitempty"`
-	NodeSelectorRequired bool                `json:"nodeSelectorRequired,omitempty"`
-	StorageClassName     string              `json:"storageClassName,omitempty"`
-	Tolerations          []corev1.Toleration `json:"tolerations,omitempty"`
-	BinlogEnabled        bool                `json:"binlogEnabled,omitempty"`
-	MaxFailoverCount     int32               `json:"maxFailoverCount,omitempty"`
+	Replicas             int32                 `json:"replicas"`
+	NodeSelector         map[string]string     `json:"nodeSelector,omitempty"`
+	NodeSelectorRequired bool                  `json:"nodeSelectorRequired,omitempty"`
+	StorageClassName     string                `json:"storageClassName,omitempty"`
+	Tolerations          []corev1.Toleration   `json:"tolerations,omitempty"`
+	BinlogEnabled        bool                  `json:"binlogEnabled,omitempty"`
+	MaxFailoverCount     int32                 `json:"maxFailoverCount,omitempty"`
+	SeparateSlowLog      bool                  `json:"separateSlowLog,omitempty"`
+	SlowLogTailer        TiDBSlowLogTailerSpec `json:"slowLogTailer,omitempty"`
+}
+
+// TiDBSlowLogTailerSpec represents an optional log tailer sidecar with TiDB
+type TiDBSlowLogTailerSpec struct {
+	ContainerSpec
 }
 
 // TiKVSpec contains details of PD member

pkg/controller/controller_utils.go

@@ -36,6 +36,8 @@ var (
 const (
 	// defaultPushgatewayImage is default image of pushgateway
 	defaultPushgatewayImage = "prom/pushgateway:v0.3.1"
+	// defaultTiDBSlowLogImage is default image of tidb log tailer
+	defaultTiDBLogTailerImage = "busybox:1.26.2"
 )
 
 // RequeueError is used to requeue the item, this error type should't be considered as a real error
@@ -129,6 +131,13 @@ func GetPushgatewayImage(cluster *v1alpha1.TidbCluster) string {
 	return defaultPushgatewayImage
 }
 
+func GetSlowLogTailerImage(cluster *v1alpha1.TidbCluster) string {
+	if img := cluster.Spec.TiDB.SlowLogTailer.Image; img != "" {
+		return img
+	}
+	return defaultTiDBLogTailerImage
+}
+
 // PDMemberName returns pd member name
 func PDMemberName(clusterName string) string {
 	return fmt.Sprintf("%s-pd", clusterName)

pkg/controller/controller_utils_test.go

@@ -157,6 +157,15 @@ func TestGetPushgatewayImage(t *testing.T) {
 	g.Expect(GetPushgatewayImage(tc)).To(Equal("image-1"))
 }
 
+func TestGetSlowLogTailerImage(t *testing.T) {
+	g := NewGomegaWithT(t)
+
+	tc := &v1alpha1.TidbCluster{}
+	g.Expect(GetSlowLogTailerImage(tc)).To(Equal(defaultTiDBLogTailerImage))
+	tc.Spec.TiDB.SlowLogTailer.Image = "image-1"
+	g.Expect(GetSlowLogTailerImage(tc)).To(Equal("image-1"))
+}
+
 func TestPDMemberName(t *testing.T) {
 	g := NewGomegaWithT(t)
 	g.Expect(PDMemberName("demo")).To(Equal("demo-pd"))

pkg/manager/member/tidb_member_manager.go

@@ -14,6 +14,7 @@
 package member
 
 import (
+	"fmt"
 	"strconv"
 
 	"github.com/pingcap/tidb-operator/pkg/apis/pingcap.com/v1alpha1"
@@ -30,6 +31,12 @@ import (
 	corelisters "k8s.io/client-go/listers/core/v1"
 )
 
+const (
+	slowQueryLogVolumeName = "slowlog"
+	slowQueryLogDir        = "/var/log/tidb"
+	slowQueryLogFile       = slowQueryLogDir + "/slowlog"
+)
+
 type tidbMemberManager struct {
 	setControl                   controller.StatefulSetControlInterface
 	svcControl                   controller.ServiceControlInterface
@@ -240,6 +247,83 @@ func (tmm *tidbMemberManager) getNewTiDBSetForTidbCluster(tc *v1alpha1.TidbClust
 		},
 	}
 
+	var containers []corev1.Container
+	if tc.Spec.TiDB.SeparateSlowLog {
+		// mount a shared volume and tail the slow log to STDOUT using a sidecar.
+		vols = append(vols, corev1.Volume{
+			Name: slowQueryLogVolumeName,
+			VolumeSource: corev1.VolumeSource{
+				EmptyDir: &corev1.EmptyDirVolumeSource{},
+			},
+		})
+		volMounts = append(volMounts, corev1.VolumeMount{Name: slowQueryLogVolumeName, MountPath: slowQueryLogDir})
+		containers = append(containers, corev1.Container{
+			Name:            v1alpha1.SlowLogTailerMemberType.String(),
+			Image:           controller.GetSlowLogTailerImage(tc),
+			ImagePullPolicy: tc.Spec.TiDB.SlowLogTailer.ImagePullPolicy,
+			Resources:       util.ResourceRequirement(tc.Spec.TiDB.SlowLogTailer.ContainerSpec),
+			VolumeMounts: []corev1.VolumeMount{
+				{Name: slowQueryLogVolumeName, MountPath: slowQueryLogDir},
+			},
+			Command: []string{
+				"sh",
+				"-c",
+				fmt.Sprintf("touch %s; tail -n0 -F %s;", slowQueryLogFile, slowQueryLogFile),
+			},
+		})
+	}
+
+	envs := []corev1.EnvVar{
+		{
+			Name:  "CLUSTER_NAME",
+			Value: tc.GetName(),
+		},
+		{
+			Name:  "TZ",
+			Value: tc.Spec.Timezone,
+		},
+		{
+			Name:  "BINLOG_ENABLED",
+			Value: strconv.FormatBool(tc.Spec.TiDB.BinlogEnabled),
+		},
+	}
+	if tc.Spec.TiDB.SeparateSlowLog {
+		envs = append(envs, corev1.EnvVar{
+			Name:  "SLOW_LOG_FILE",
+			Value: slowQueryLogFile,
+		})
+	}
+	containers = append(containers, corev1.Container{
+		Name:            v1alpha1.TiDBMemberType.String(),
+		Image:           tc.Spec.TiDB.Image,
+		Command:         []string{"/bin/sh", "/usr/local/bin/tidb_start_script.sh"},
+		ImagePullPolicy: tc.Spec.TiDB.ImagePullPolicy,
+		Ports: []corev1.ContainerPort{
+			{
+				Name:          "server",
+				ContainerPort: int32(4000),
+				Protocol:      corev1.ProtocolTCP,
+			},
+			{
+				Name:          "status", // pprof, status, metrics
+				ContainerPort: int32(10080),
+				Protocol:      corev1.ProtocolTCP,
+			},
+		},
+		VolumeMounts: volMounts,
+		Resources:    util.ResourceRequirement(tc.Spec.TiDB.ContainerSpec),
+		Env:          envs,
+		ReadinessProbe: &corev1.Probe{
+			Handler: corev1.Handler{
+				HTTPGet: &corev1.HTTPGetAction{
+					Path: "/status",
+					Port: intstr.FromInt(10080),
+				},
+			},
+			InitialDelaySeconds: int32(10),
+		},
+	})
+
 	tidbLabel := label.New().Instance(instanceName).TiDB()
 	tidbSet := &apps.StatefulSet{
 		ObjectMeta: metav1.ObjectMeta{
@@ -264,51 +348,7 @@ func (tmm *tidbMemberManager) getNewTiDBSetForTidbCluster(tc *v1alpha1.TidbClust
 						label.New().Instance(instanceName).TiDB(),
 						tc.Spec.TiDB.NodeSelector,
 					),
-					Containers: []corev1.Container{
-						{
-							Name:            v1alpha1.TiDBMemberType.String(),
-							Image:           tc.Spec.TiDB.Image,
-							Command:         []string{"/bin/sh", "/usr/local/bin/tidb_start_script.sh"},
-							ImagePullPolicy: tc.Spec.TiDB.ImagePullPolicy,
-							Ports: []corev1.ContainerPort{
-								{
-									Name:          "server",
-									ContainerPort: int32(4000),
-									Protocol:      corev1.ProtocolTCP,
-								},
-								{
-									Name:          "status", // pprof, status, metrics
-									ContainerPort: int32(10080),
-									Protocol:      corev1.ProtocolTCP,
-								},
-							},
-							VolumeMounts: volMounts,
-							Resources:    util.ResourceRequirement(tc.Spec.TiDB.ContainerSpec),
-							Env: []corev1.EnvVar{
-								{
-									Name:  "CLUSTER_NAME",
-									Value: tc.GetName(),
-								},
-								{
-									Name:  "TZ",
-									Value: tc.Spec.Timezone,
-								},
-								{
-									Name:  "BINLOG_ENABLED",
-									Value: strconv.FormatBool(tc.Spec.TiDB.BinlogEnabled),
-								},
-							},
-							ReadinessProbe: &corev1.Probe{
-								Handler: corev1.Handler{
-									HTTPGet: &corev1.HTTPGetAction{
-										Path: "/status",
-										Port: intstr.FromInt(10080),
-									},
-								},
-								InitialDelaySeconds: int32(10),
-							},
-						},
-					},
+					Containers:    containers,
 					RestartPolicy: corev1.RestartPolicyAlways,
 					Tolerations:   tc.Spec.TiDB.Tolerations,
 					Volumes:       vols,

pkg/manager/member/tidb_member_manager_test.go

@@ -209,6 +209,18 @@ func TestTiDBMemberManagerSyncUpdate(t *testing.T) {
 				g.Expect(err).NotTo(HaveOccurred())
 			},
 		},
+		{
+			name: "enable separate slowlog on the fly",
+			modify: func(tc *v1alpha1.TidbCluster) {
+				tc.Spec.TiDB.SeparateSlowLog = true
+			},
+			errWhenUpdateStatefulSet: false,
+			err:                      false,
+			expectStatefulSetFn: func(g *GomegaWithT, set *apps.StatefulSet, err error) {
+				g.Expect(err).NotTo(HaveOccurred())
+				g.Expect(set.Spec.Template.Spec.Containers).To(HaveLen(2))
+			},
+		},
 	}
 
 	for i := range tests {