Add an elasticsearch scaler based on search template

.pre-commit-config.yaml

@@ -32,7 +32,7 @@ repos:
       entry: "(?i)(black|white)[_-]?(list|List)"
       pass_filenames: true
     - id: sort-scalers
-      name: Check if scalers are sorted in scaler_handler.go
+      name: Check if scalers are sorted in scale_handler.go
       language: system
       entry: "bash tools/sort_scalers.sh"
       files: .*scale_handler\.go$

CHANGELOG.md

@@ -29,6 +29,7 @@
 - Improve Redis Scaler, upgrade library, add username and Sentinel support ([#2181](https://github.com/kedacore/keda/pull/2181))
 - Add GCP identity authentication when using Pubsub Scaler ([#2225](https://github.com/kedacore/keda/pull/2225))
 - Add ScalersCache to reuse scalers unless they need changing ([#2187](https://github.com/kedacore/keda/pull/2187))
+- Add an elasticsearch scaler based on search template ([#2304](https://github.com/kedacore/keda/pull/2304))
 
 ### Improvements
 

go.mod

@@ -17,6 +17,7 @@ require (
 	github.com/Shopify/sarama v1.30.0
 	github.com/aws/aws-sdk-go v1.42.3
 	github.com/denisenkom/go-mssqldb v0.11.0
+	github.com/elastic/go-elasticsearch/v7 v7.15.1
 	github.com/go-logr/logr v0.4.0
 	github.com/go-playground/assert/v2 v2.0.1
 	github.com/go-redis/redis/v8 v8.11.4

go.sum

@@ -254,6 +254,8 @@ github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21 h1:YEetp8
 github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21/go.mod h1:+020luEh2TKB4/GOp8oxxtq0Daoen/Cii55CzbTV6DU=
 github.com/eapache/queue v1.1.0 h1:YOEu7KNc61ntiQlcEeUIoDTJ2o8mQznoNvUhiigpIqc=
 github.com/eapache/queue v1.1.0/go.mod h1:6eCeP0CKFpHLu8blIFXhExK/dRa7WDZfr6jVFPTqq+I=
+github.com/elastic/go-elasticsearch/v7 v7.15.1 h1:Wd8RLHb5D8xPBU8vGlnLXyflkso9G+rCmsXjqH8LLQQ=
+github.com/elastic/go-elasticsearch/v7 v7.15.1/go.mod h1:OJ4wdbtDNk5g503kvlHLyErCgQwwzmDtaFC4XyOxXA4=
 github.com/elazarl/goproxy v0.0.0-20180725130230-947c36da3153/go.mod h1:/Zj4wYkgs4iZTTu3o/KG3Itv/qCCa8VVMlb3i9OVuzc=
 github.com/emicklei/go-restful v0.0.0-20170410110728-ff4f55a20633/go.mod h1:otzb+WCGbkyDHkqmQmT5YD2WR4BBwUdeQoFo8l/7tVs=
 github.com/emicklei/go-restful v2.9.5+incompatible/go.mod h1:otzb+WCGbkyDHkqmQmT5YD2WR4BBwUdeQoFo8l/7tVs=

pkg/scalers/elasticsearch_scaler.go

@@ -0,0 +1,277 @@
+package scalers
+
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/elastic/go-elasticsearch/v7"
+	kedautil "github.com/kedacore/keda/v2/pkg/util"
+	"github.com/tidwall/gjson"
+	"k8s.io/api/autoscaling/v2beta2"
+	"k8s.io/apimachinery/pkg/api/resource"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/metrics/pkg/apis/external_metrics"
+	logf "sigs.k8s.io/controller-runtime/pkg/log"
+)
+
+type elasticsearchScaler struct {
+	metadata *elasticsearchMetadata
+	esClient *elasticsearch.Client
+}
+
+type elasticsearchMetadata struct {
+	addresses          []string
+	unsafeSsl          bool
+	username           string
+	password           string
+	indexes            []string
+	searchTemplateName string
+	parameters         []string
+	valueLocation      string
+	targetValue        int
+}
+
+var elasticsearchLog = logf.Log.WithName("elasticsearch_scaler")
+
+// NewElasticsearchScaler creates a new elasticsearch scaler
+func NewElasticsearchScaler(config *ScalerConfig) (Scaler, error) {
+	meta, err := parseElasticsearchMetadata(config)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing elasticsearch metadata: %s", err)
+	}
+
+	esClient, err := newElasticsearchClient(meta)
+	if err != nil {
+		return nil, fmt.Errorf("error getting elasticsearch client: %s", err)
+	}
+	return &elasticsearchScaler{
+		metadata: meta,
+		esClient: esClient,
+	}, nil
+}
+
+const defaultUnsafeSsl = false
+
+func parseElasticsearchMetadata(config *ScalerConfig) (*elasticsearchMetadata, error) {
+	meta := elasticsearchMetadata{}
+
+	var err error
+	addresses, err := GetFromAuthOrMeta(config, "addresses")
+	if err != nil {
+		return nil, err
+	}
+	meta.addresses = splitAndTrimBySep(addresses, ",")
+
+	if val, ok := config.TriggerMetadata["unsafeSsl"]; ok {
+		meta.unsafeSsl, err = strconv.ParseBool(val)
+		if err != nil {
+			return nil, fmt.Errorf("error parsing unsafeSsL: %s", err)
+		}
+	} else {
+		meta.unsafeSsl = defaultUnsafeSsl
+	}
+
+	if val, ok := config.AuthParams["username"]; ok {
+		meta.username = val
+	} else if val, ok := config.TriggerMetadata["username"]; ok {
+		meta.username = val
+	}
+
+	if config.AuthParams["password"] != "" {
+		meta.password = config.AuthParams["password"]
+	} else if config.TriggerMetadata["passwordFromEnv"] != "" {
+		meta.password = config.ResolvedEnv[config.TriggerMetadata["passwordFromEnv"]]
+	}
+
+	index, err := GetFromAuthOrMeta(config, "index")
+	if err != nil {
+		return nil, err
+	}
+	meta.indexes = splitAndTrimBySep(index, ";")
+
+	meta.searchTemplateName, err = GetFromAuthOrMeta(config, "searchTemplateName")
+	if err != nil {
+		return nil, err
+	}
+
+	if val, ok := config.TriggerMetadata["parameters"]; ok {
+		meta.parameters = splitAndTrimBySep(val, ";")
+	}
+
+	meta.valueLocation, err = GetFromAuthOrMeta(config, "valueLocation")
+	if err != nil {
+		return nil, err
+	}
+
+	targetValue, err := GetFromAuthOrMeta(config, "targetValue")
+	if err != nil {
+		return nil, err
+	}
+	meta.targetValue, err = strconv.Atoi(targetValue)
+	if err != nil {
+		return nil, fmt.Errorf("targetValue parsing error %s", err.Error())
+	}
+
+	return &meta, nil
+}
+
+// newElasticsearchClient creates elasticsearch db connection
+func newElasticsearchClient(meta *elasticsearchMetadata) (*elasticsearch.Client, error) {
+	config := elasticsearch.Config{Addresses: meta.addresses}
+	if meta.username != "" {
+		config.Username = meta.username
+	}
+	if meta.password != "" {
+		config.Password = meta.password
+	}
+
+	if meta.unsafeSsl {
+		tr := &http.Transport{
+			TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
+		}
+		config.Transport = tr
+	}
+
+	esClient, err := elasticsearch.NewClient(config)
+	if err != nil {
+		elasticsearchLog.Error(err, fmt.Sprintf("Found error when creating client: %s", err))
+		return nil, err
+	}
+
+	_, err = esClient.Info()
+	if err != nil {
+		elasticsearchLog.Error(err, fmt.Sprintf("Found error when pinging search engine: %s", err))
+		return nil, err
+	}
+	return esClient, nil
+}
+
+func (s *elasticsearchScaler) Close(ctx context.Context) error {
+	return nil
+}
+
+// IsActive returns true if there are pending messages to be processed
+func (s *elasticsearchScaler) IsActive(ctx context.Context) (bool, error) {
+	messages, err := s.getQueryResult()
+	if err != nil {
+		elasticsearchLog.Error(err, fmt.Sprintf("Error inspecting elasticsearch: %s", err))
+		return false, err
+	}
+	return messages > 0, nil
+}
+
+// getQueryResult returns result of the scaler query
+func (s *elasticsearchScaler) getQueryResult() (int, error) {
+	// Build the request body.
+	var body bytes.Buffer
+	if err := json.NewEncoder(&body).Encode(buildQuery(s.metadata)); err != nil {
+		elasticsearchLog.Error(err, "Error encoding query: %s", err)
+	}
+
+	// Run the templated search
+	res, err := s.esClient.SearchTemplate(
+		&body,
+		s.esClient.SearchTemplate.WithIndex(s.metadata.indexes...),
+	)
+	if err != nil {
+		elasticsearchLog.Error(err, fmt.Sprintf("Could not query elasticsearch: %s", err))
+		return 0, err
+	}
+
+	defer res.Body.Close()
+	b, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		return 0, err
+	}
+	v, err := getValueFromSearch(b, s.metadata.valueLocation)
+	if err != nil {
+		return 0, err
+	}
+	return v, nil
+}
+
+func buildQuery(metadata *elasticsearchMetadata) map[string]interface{} {
+	parameters := map[string]interface{}{}
+	for _, p := range metadata.parameters {
+		if p != "" {
+			kv := splitAndTrimBySep(p, ":")
+			parameters[kv[0]] = kv[1]
+		}
+	}
+	query := map[string]interface{}{
+		"id": metadata.searchTemplateName,
+	}
+	if len(parameters) > 0 {
+		query["params"] = parameters
+	}
+	return query
+}
+
+func getValueFromSearch(body []byte, valueLocation string) (int, error) {
+	r := gjson.GetBytes(body, valueLocation)
+	errorMsg := "valueLocation must point to value of type number but got: '%s'"
+	if r.Type == gjson.String {
+		q, err := strconv.Atoi(r.String())
+		if err != nil {
+			return 0, fmt.Errorf(errorMsg, r.String())
+		}
+		return q, nil
+	}
+	if r.Type != gjson.Number {
+		return 0, fmt.Errorf(errorMsg, r.Type.String())
+	}
+	return int(r.Num), nil
+}
+
+// GetMetricSpecForScaling returns the MetricSpec for the Horizontal Pod Autoscaler
+func (s *elasticsearchScaler) GetMetricSpecForScaling(context.Context) []v2beta2.MetricSpec {
+	targetValue := resource.NewQuantity(int64(s.metadata.targetValue), resource.DecimalSI)
+	metricName := kedautil.NormalizeString(fmt.Sprintf("elasticsearch-%s", s.metadata.searchTemplateName))
+
+	externalMetric := &v2beta2.ExternalMetricSource{
+		Metric: v2beta2.MetricIdentifier{
+			Name: GenerateMetricNameWithIndex(s.metadata.targetValue, metricName),
+		},
+		Target: v2beta2.MetricTarget{
+			Type:         v2beta2.AverageValueMetricType,
+			AverageValue: targetValue,
+		},
+	}
+	metricSpec := v2beta2.MetricSpec{
+		External: externalMetric, Type: externalMetricType,
+	}
+	return []v2beta2.MetricSpec{metricSpec}
+}
+
+// GetMetrics returns value for a supported metric and an error if there is a problem getting the metric
+func (s *elasticsearchScaler) GetMetrics(ctx context.Context, metricName string, metricSelector labels.Selector) ([]external_metrics.ExternalMetricValue, error) {
+	num, err := s.getQueryResult()
+	if err != nil {
+		return []external_metrics.ExternalMetricValue{}, fmt.Errorf("error inspecting elasticsearch: %s", err)
+	}
+
+	metric := external_metrics.ExternalMetricValue{
+		MetricName: metricName,
+		Value:      *resource.NewQuantity(int64(num), resource.DecimalSI),
+		Timestamp:  metav1.Now(),
+	}
+
+	return append([]external_metrics.ExternalMetricValue{}, metric), nil
+}
+
+// Splits a string separated by a specified separator and trims space from all the elements.
+func splitAndTrimBySep(s string, sep string) []string {
+	x := strings.Split(s, sep)
+	for i := range x {
+		x[i] = strings.Trim(x[i], " ")
+	}
+	return x
+}