feat: Introduce activationThreshold/minMetricValue for MySQL Scaler

pkg/scalers/mysql_scaler.go

@@ -23,15 +23,16 @@ type mySQLScaler struct {
 }
 
 type mySQLMetadata struct {
-	connectionString string // Database connection string
-	username         string
-	password         string
-	host             string
-	port             string
-	dbName           string
-	query            string
-	queryValue       float64
-	metricName       string
+	connectionString     string // Database connection string
+	username             string
+	password             string
+	host                 string
+	port                 string
+	dbName               string
+	query                string
+	queryValue           float64
+	activationQueryValue float64
+	metricName           string
 }
 
 var mySQLLog = logf.Log.WithName("mysql_scaler")
@@ -78,6 +79,15 @@ func parseMySQLMetadata(config *ScalerConfig) (*mySQLMetadata, error) {
 		return nil, fmt.Errorf("no queryValue given")
 	}
 
+	meta.activationQueryValue = 0
+	if val, ok := config.TriggerMetadata["activationQueryValue"]; ok {
+		activationQueryValue, err := strconv.ParseFloat(val, 64)
+		if err != nil {
+			return nil, fmt.Errorf("activationQueryValue parsing error %s", err.Error())
+		}
+		meta.activationQueryValue = activationQueryValue
+	}
+
 	switch {
 	case config.AuthParams["connectionString"] != "":
 		meta.connectionString = config.AuthParams["connectionString"]
@@ -188,7 +198,7 @@ func (s *mySQLScaler) IsActive(ctx context.Context) (bool, error) {
 		mySQLLog.Error(err, fmt.Sprintf("Error inspecting MySQL: %s", err))
 		return false, err
 	}
-	return messages > 0, nil
+	return messages > s.metadata.activationQueryValue, nil
 }
 
 // getQueryResult returns result of the scaler query

pkg/scalers/mysql_scaler_test.go

@@ -51,6 +51,13 @@ var testMySQLMetadata = []parseMySQLMetadataTestData{
 		resolvedEnv: testMySQLResolvedEnv,
 		raisesError: false,
 	},
+	// Invalid activationQueryValue
+	{
+		metadata:    map[string]string{"query": "query", "queryValue": "12", "activationQueryValue": "AA"},
+		authParams:  map[string]string{"host": "test_host", "port": "test_port", "username": "test_username", "password": "MYSQL_PASSWORD", "dbName": "test_dbname"},
+		resolvedEnv: testMySQLResolvedEnv,
+		raisesError: true,
+	},
 }
 
 var mySQLMetricIdentifiers = []mySQLMetricIdentifier{

tests/scalers_go/mysql/mysql_test.go

@@ -45,6 +45,7 @@ type templateData struct {
 	MySQLDatabase         string
 	MySQLRootPassword     string
 	MySQLConnectionString string
+	ItemsToWrite          int
 }
 
 type templateValues map[string]string
@@ -126,6 +127,7 @@ spec:
   - type: mysql
     metadata:
       queryValue: "4"
+      activationQueryValue: "100"
       query: "SELECT CEIL(COUNT(*) / 5) FROM task_instance WHERE state='running' OR state='queued'"
     authenticationRef:
       name: keda-trigger-auth-mysql-secret
@@ -140,6 +142,7 @@ metadata:
   name: mysql-insert-job
   namespace: {{.TestNamespace}}
 spec:
+  ttlSecondsAfterFinished: 0
   template:
     metadata:
       labels:
@@ -154,7 +157,7 @@ spec:
           - insert
         env:
           - name: TASK_INSTANCES_COUNT
-            value: "4000"
+            value: "{{.ItemsToWrite}}"
           - name: CONNECTION_STRING
             valueFrom:
               secretKeyRef:
@@ -235,6 +238,7 @@ func TestMySQLScaler(t *testing.T) {
 	setupMySQL(t, kc, data, templates)
 
 	// test scaling
+	testActivation(t, kc, data)
 	testScaleUp(t, kc, data)
 	testScaleDown(t, kc)
 
@@ -266,9 +270,19 @@ func setupMySQL(t *testing.T, kc *kubernetes.Clientset, data templateData, templ
 		"replica count should start out as 0")
 }
 
+func testActivation(t *testing.T, kc *kubernetes.Clientset, data templateData) {
+	t.Log("--- testing activation ---")
+	t.Log("--- applying job ---")
+	data.ItemsToWrite = 50
+	KubectlApplyWithTemplate(t, data, "insertRecordsJobTemplate", insertRecordsJobTemplate)
+
+	AssertReplicaCountNotChangeDuringTimePeriod(t, kc, deploymentName, testNamespace, 0, 60)
+}
+
 func testScaleUp(t *testing.T, kc *kubernetes.Clientset, data templateData) {
 	t.Log("--- testing scale up ---")
 	t.Log("--- applying job ---")
+	data.ItemsToWrite = 4000
 	KubectlApplyWithTemplate(t, data, "insertRecordsJobTemplate", insertRecordsJobTemplate)
 	// Check if deployment scale to 2 (the max)
 	maxReplicaCount := 2
@@ -295,6 +309,7 @@ func getTemplateData() (templateData, templateValues) {
 			MySQLDatabase:         mySQLDatabase,
 			MySQLRootPassword:     mySQLRootPassword,
 			MySQLConnectionString: base64MySQLConnectionString,
+			ItemsToWrite:          0,
 		}, templateValues{
 			"deploymentTemplate":   deploymentTemplate,
 			"secretTemplate":       secretTemplate,