Add auto-scaling calculation based by CPU load

pkg/autoscaler/autoscaler/calculate/calculate.go

@@ -0,0 +1,95 @@
+// Copyright 2020 PingCAP, Inc.
+//
+// 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,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package calculate
+
+import (
+	"encoding/json"
+	"fmt"
+	"math"
+	"net/http"
+	"strconv"
+
+	"github.com/pingcap/tidb-operator/pkg/apis/pingcap/v1alpha1"
+	promClient "github.com/prometheus/client_golang/api"
+	"k8s.io/apimachinery/pkg/util/sets"
+)
+
+const (
+	TikvSumCpuMetricsPattern     = `sum(tikv_thread_cpu_seconds_total{cluster="%s"}) by (instance)`
+	TidbSumCpuMetricsPattern     = `sum(process_cpu_seconds_total{cluster="%s",job="tidb"}) by (instance)`
+	InvalidTacMetricConfigureMsg = "tac[%s/%s] metric configuration invalid"
+	CpuSumMetricsErrorMsg        = "tac[%s/%s] cpu sum metrics error, can't calculate the past %s cpu metrics, may caused by prometheus restart while data persistence not enabled"
+	queryPath                    = "/api/v1/query"
+
+	float64EqualityThreshold = 1e-9
+)
+
+func queryMetricsFromPrometheus(tac *v1alpha1.TidbClusterAutoScaler,
+	query string, client promClient.Client, timestamp int64, resp *Response) error {
+	req, err := http.NewRequest("GET", fmt.Sprintf("%s%s", *tac.Spec.MetricsUrl, queryPath), nil)
+	if err != nil {
+		return err
+	}
+	q := req.URL.Query()
+	q.Add("query", query)
+	q.Add("time", fmt.Sprintf("%d", timestamp))
+	req.URL.RawQuery = q.Encode()
+	r, body, err := client.Do(req.Context(), req)
+	if err != nil {
+		return err
+	}
+	if r.StatusCode != http.StatusOK {
+		return fmt.Errorf("tac[%s/%s] query error, status code:%d", tac.Namespace, tac.Name, r.StatusCode)
+	}
+	err = json.Unmarshal(body, resp)
+	if err != nil {
+		return err
+	}
+	if resp.Status != statusSuccess {
+		return fmt.Errorf("tac[%s/%s] query error, response status: %v", tac.Namespace, tac.Name, resp.Status)
+	}
+	return nil
+}
+
+// sumByInstanceFromResponse sum the value in Response of each instance from Prometheus
+func sumByInstanceFromResponse(instances []string, resp *Response) (float64, error) {
+	s := sets.String{}
+	for _, instance := range instances {
+		s.Insert(instance)
+	}
+	sum := 0.0
+	for _, r := range resp.Data.Result {
+		if s.Has(r.Metric.Instance) {
+			v, err := strconv.ParseFloat(r.Value[1].(string), 64)
+			if err != nil {
+				return 0.0, err
+			}
+			sum = sum + v
+		}
+	}
+	return sum, nil
+}
+
+// calculate func calculate the recommended replicas by given usageRatio and currentReplicas
+func calculate(currentValue float64, targetValue float64, currentReplicas int32) (int32, error) {
+	if almostEqual(targetValue, 0.0) {
+		return 0, fmt.Errorf("targetValue in calculate func can't be zero")
+	}
+	usageRatio := currentValue / targetValue
+	return int32(math.Ceil(usageRatio * float64(currentReplicas))), nil
+}
+
+func almostEqual(a, b float64) bool {
+	return math.Abs(a-b) <= float64EqualityThreshold
+}

pkg/autoscaler/autoscaler/calculate/cpu.go

@@ -0,0 +1,85 @@
+// Copyright 2020 PingCAP, Inc.
+//
+// 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,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package calculate
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/pingcap/tidb-operator/pkg/apis/pingcap/v1alpha1"
+	promClient "github.com/prometheus/client_golang/api"
+	appsv1 "k8s.io/api/apps/v1"
+	autoscalingv2beta2 "k8s.io/api/autoscaling/v2beta2"
+	corev1 "k8s.io/api/core/v1"
+)
+
+//TODO: create issue to explain how auto-scaling algorithm based on cpu metrics work
+func CalculateCpuMetrics(tac *v1alpha1.TidbClusterAutoScaler, sts *appsv1.StatefulSet,
+	client promClient.Client, instances []string, metric autoscalingv2beta2.MetricSpec,
+	queryPattern, timeWindow string, memberType v1alpha1.MemberType) (int32, error) {
+	if metric.Resource == nil || metric.Resource.Target.AverageUtilization == nil {
+		return 0, fmt.Errorf(InvalidTacMetricConfigureMsg, tac.Namespace, tac.Name)
+	}
+	currentReplicas := len(instances)
+	c, err := filterContainer(tac, sts, memberType.String())
+	if err != nil {
+		return 0, err
+	}
+	cpuRequestsRatio, err := extractCpuRequestsRatio(c)
+	if err != nil {
+		return 0, err
+	}
+	now := time.Now()
+	duration, err := time.ParseDuration(timeWindow)
+	if err != nil {
+		return 0, err
+	}
+	prvious := now.Truncate(duration)
+	r := &Response{}
+	err = queryMetricsFromPrometheus(tac, fmt.Sprintf(queryPattern, tac.Spec.Cluster.Name), client, now.Unix(), r)
+	if err != nil {
+		return 0, err
+	}
+	sum1, err := sumByInstanceFromResponse(instances, r)
+	if err != nil {
+		return 0, err
+	}
+	err = queryMetricsFromPrometheus(tac, fmt.Sprintf(queryPattern, tac.Spec.Cluster.Name), client, prvious.Unix(), r)
+	if err != nil {
+		return 0, err
+	}
+	sum2, err := sumByInstanceFromResponse(instances, r)
+	if err != nil {
+		return 0, err
+	}
+	if sum1-sum2 < 0 {
+		return 0, fmt.Errorf(CpuSumMetricsErrorMsg, tac.Namespace, tac.Name, timeWindow)
+	}
+	cpuSecsTotal := sum1 - sum2
+	durationSeconds := duration.Seconds()
+	utilizationRatio := float64(*metric.Resource.Target.AverageUtilization) / 100.0
+	expectedCpuSecsTotal := cpuRequestsRatio * durationSeconds * float64(currentReplicas) * utilizationRatio
+	rc, err := calculate(cpuSecsTotal, expectedCpuSecsTotal, int32(currentReplicas))
+	if err != nil {
+		return 0, err
+	}
+	return rc, nil
+}
+
+func extractCpuRequestsRatio(c *corev1.Container) (float64, error) {
+	if c.Resources.Requests.Cpu() == nil || c.Resources.Requests.Cpu().MilliValue() < 1 {
+		return 0, fmt.Errorf("container[%s] cpu requests is empty", c.Name)
+	}
+	return float64(c.Resources.Requests.Cpu().MilliValue()) / 1000.0, nil
+}

pkg/autoscaler/autoscaler/calculate/util.go

@@ -0,0 +1,89 @@
+// Copyright 2020 PingCAP, Inc.
+//
+// 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,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package calculate
+
+import (
+	"fmt"
+
+	"github.com/pingcap/tidb-operator/pkg/apis/pingcap/v1alpha1"
+	appsv1 "k8s.io/api/apps/v1"
+	autoscalingv2beta2 "k8s.io/api/autoscaling/v2beta2"
+	corev1 "k8s.io/api/core/v1"
+)
+
+// currently, we only choose one metrics to be computed.
+// If there exists several metrics, we tend to choose ResourceMetricSourceType metric
+func FilterMetrics(metrics []autoscalingv2beta2.MetricSpec) autoscalingv2beta2.MetricSpec {
+	for _, m := range metrics {
+		if m.Type == autoscalingv2beta2.ResourceMetricSourceType && m.Resource != nil {
+			return m
+		}
+	}
+	return metrics[0]
+}
+
+// MetricType describe the current Supported Metric Type to calculate the recommended Replicas
+type MetricType string
+
+const (
+	MetricTypeCPU MetricType = "cpu"
+	//metricTypeQPS MetricType = "qps"
+)
+
+// genMetricType return the supported MetricType in Operator by kubernetes auto-scaling MetricType
+func GenMetricType(tac *v1alpha1.TidbClusterAutoScaler, metric autoscalingv2beta2.MetricSpec) (MetricType, error) {
+	if metric.Type == autoscalingv2beta2.ResourceMetricSourceType && metric.Resource != nil && metric.Resource.Name == corev1.ResourceCPU {
+		return MetricTypeCPU, nil
+	}
+	return "", fmt.Errorf(InvalidTacMetricConfigureMsg, tac.Namespace, tac.Name)
+}
+
+// filterContainer is to filter the specific container from the given statefulset(tidb/tikv)
+func filterContainer(tac *v1alpha1.TidbClusterAutoScaler, sts *appsv1.StatefulSet, containerName string) (*corev1.Container, error) {
+	for _, c := range sts.Spec.Template.Spec.Containers {
+		if c.Name == containerName {
+			return &c, nil
+		}
+	}
+	return nil, fmt.Errorf("tac[%s/%s]'s Target have not %s container", tac.Namespace, tac.Name, containerName)
+}
+
+const (
+	statusSuccess = "success"
+)
+
+// Response is used to marshal the data queried from Prometheus
+type Response struct {
+	Status string `json:"status"`
+	Data   Data   `json:"data"`
+}
+
+type Data struct {
+	ResultType string   `json:"resultType"`
+	Result     []Result `json:"result"`
+}
+
+type Result struct {
+	Metric Metric        `json:"metric"`
+	Value  []interface{} `json:"value"`
+}
+
+type Metric struct {
+	Cluster             string `json:"cluster,omitempty"`
+	Instance            string `json:"instance"`
+	Job                 string `json:"job,omitempty"`
+	KubernetesNamespace string `json:"kubernetes_namespace,omitempty"`
+	KubernetesNode      string `json:"kubernetes_node,omitempty"`
+	KubernetesPodIp     string `json:"kubernetes_pod_ip,omitempty"`
+}

pkg/autoscaler/autoscaler/tidb_autoscaler.go

@@ -14,12 +14,15 @@
 package autoscaler
 
 import (
+	"fmt"
 	"time"
 
 	"github.com/pingcap/tidb-operator/pkg/apis/pingcap/v1alpha1"
+	"github.com/pingcap/tidb-operator/pkg/autoscaler/autoscaler/calculate"
 	"github.com/pingcap/tidb-operator/pkg/label"
 	operatorUtils "github.com/pingcap/tidb-operator/pkg/util"
 	promClient "github.com/prometheus/client_golang/api"
+	appsv1 "k8s.io/api/apps/v1"
 )
 
 func (am *autoScalerManager) syncTiDB(tc *v1alpha1.TidbCluster, tac *v1alpha1.TidbClusterAutoScaler, client promClient.Client) error {
@@ -36,7 +39,11 @@ func (am *autoScalerManager) syncTiDB(tc *v1alpha1.TidbCluster, tac *v1alpha1.Ti
 		return nil
 	}
 	currentReplicas := tc.Spec.TiDB.Replicas
-	targetReplicas := calculateRecommendedReplicas(tac, v1alpha1.TiDBMemberType, client)
+	instances := filterTidbInstances(tc)
+	targetReplicas, err := calculateTidbMetrics(tac, sts, client, instances)
+	if err != nil {
+		return err
+	}
 	targetReplicas = limitTargetReplicas(targetReplicas, tac, v1alpha1.TiDBMemberType)
 	if targetReplicas == tc.Spec.TiDB.Replicas {
 		emptyAutoScalingCountAnn(tac, v1alpha1.TiDBMemberType)
@@ -80,3 +87,25 @@ func updateTcTiDBAnnIfScale(tac *v1alpha1.TidbClusterAutoScaler) {
 	tac.Annotations[label.AnnTiDBLastAutoScalingTimestamp] = time.Now().String()
 	emptyAutoScalingCountAnn(tac, v1alpha1.TiDBMemberType)
 }
+
+func calculateTidbMetrics(tac *v1alpha1.TidbClusterAutoScaler, sts *appsv1.StatefulSet, client promClient.Client, instances []string) (int32, error) {
+	metric := calculate.FilterMetrics(tac.Spec.TiDB.Metrics)
+	mType, err := calculate.GenMetricType(tac, metric)
+	if err != nil {
+		return 0, err
+	}
+	switch mType {
+	case calculate.MetricTypeCPU:
+		return calculate.CalculateCpuMetrics(tac, sts, client, instances, metric, calculate.TidbSumCpuMetricsPattern, *tac.Spec.TiDB.MetricsTimeDuration, v1alpha1.TiDBMemberType)
+	default:
+		return 0, fmt.Errorf(calculate.InvalidTacMetricConfigureMsg, tac.Namespace, tac.Name)
+	}
+}
+
+func filterTidbInstances(tc *v1alpha1.TidbCluster) []string {
+	var instances []string
+	for i := 0; int32(i) < tc.Spec.TiDB.Replicas; i++ {
+		instances = append(instances, operatorUtils.GetPodName(tc, v1alpha1.TiDBMemberType, int32(i)))
+	}
+	return instances
+}

pkg/autoscaler/autoscaler/tidb_autoscaler_test.go

@@ -42,6 +42,7 @@ func TestSyncTiDBAfterCalculated(t *testing.T) {
 		tc.Spec.TiDB.Replicas = test.currentReplicas
 		tac.Annotations[label.AnnTiDBConsecutiveScaleInCount] = fmt.Sprintf("%d", test.currentScaleInCount)
 		tac.Annotations[label.AnnTiDBConsecutiveScaleOutCount] = fmt.Sprintf("%d", test.currentScaleOutCount)
+		tac.Spec.TiKV = nil
 
 		err := syncTiDBAfterCalculated(tc, tac, test.currentReplicas, test.recommendedReplicas)
 		g.Expect(err).ShouldNot(HaveOccurred())