[KEDA] Selenium Grid: Add trigger param overProvisionRatio for ability to scale more than queue request (SeleniumHQ#2907)

Signed-off-by: Viet Nguyen Duc <[email protected]>

Author: VietND96

.keda/README.md

@@ -13,9 +13,9 @@ The stable implementation will be merged to the upstream KEDA repository frequen
 Replace the image registry and tag of these KEDA components with the patched image tag:
 
 ```bash
-docker pull selenium/keda:2.17.2-selenium-grid-20250717
-docker pull selenium/keda-metrics-apiserver:2.17.2-selenium-grid-20250717
-docker pull selenium/keda-admission-webhooks:2.17.2-selenium-grid-20250717
+docker pull selenium/keda:2.17.2-selenium-grid-20250721
+docker pull selenium/keda-metrics-apiserver:2.17.2-selenium-grid-20250721
+docker pull selenium/keda-admission-webhooks:2.17.2-selenium-grid-20250721
 ```
 
 Besides that, you also can use image tag `latest` or `nightly`.
@@ -27,15 +27,15 @@ If you are deploying KEDA core using their official Helm [chart](https://github.
     keda:
       registry: selenium
       repository: keda
-      tag: "2.17.2-selenium-grid-20250717"
+      tag: "2.17.2-selenium-grid-20250721"
     metricsApiServer:
       registry: selenium
       repository: keda-metrics-apiserver
-      tag: "2.17.2-selenium-grid-20250717"
+      tag: "2.17.2-selenium-grid-20250721"
     webhooks:
       registry: selenium
       repository: keda-admission-webhooks
-      tag: "2.17.2-selenium-grid-20250717"
+      tag: "2.17.2-selenium-grid-20250721"
 ```
 
 If you are deployment Selenium Grid chart with `autoscaling.enabled` is `true` (implies installing KEDA sub-chart), KEDA images registry and tag already set in the `values.yaml`. Refer to list [configuration](../charts/selenium-grid/CONFIGURATION.md).
@@ -49,6 +49,8 @@ You can involve to review and discuss the pull requests to help us early detect
 
 [kedacore/keda](https://github.com/kedacore/keda)
 
+- https://github.com/kedacore/keda/pull/6920 (planned, v2.18.0)
+
 - ~~https://github.com/kedacore/keda/pull/6772 (merged, v2.17.1)~~
 
 - ~~https://github.com/kedacore/keda/pull/6684 (merged, v2.17.0)~~

.keda/scalers/selenium-grid-scaler.md

@@ -28,6 +28,7 @@ triggers:
       nodeMaxSessions: 1 # Optional.
       enableManagedDownloads: true # Optional.
       capabilities: '' # Optional.
+      overProvisionRatio: '' # Optional.
 ```
 
 **Parameter list:**
@@ -42,13 +43,16 @@ triggers:
 - `nodeMaxSessions` - Number of maximum sessions that can run in parallel on a Node. Update this parameter align with node config `--max-sessions` (`SE_NODE_MAX_SESSIONS`) to have the correct scaling behavior. (Default: `1`, Optional).
 - `enableManagedDownloads`- Set this for Node enabled to auto manage files downloaded for a given session on the Node. When the client requests enabling this feature, it can only be assigned to the Node that also enabled it. Otherwise, the request will wait until it timed out. (Default: `true`, Optional).
 - `capabilities` - Add more custom capabilities for matching specific Nodes. It should be in JSON string, see [example](https://www.selenium.dev/documentation/grid/configuration/toml_options/#setting-custom-capabilities-for-matching-specific-nodes) (Optional)
+- `overProvisionRatio` - The number of overprovisioning ratio to scale more than the actual number of requests. For example, if there are 20 requests for the browser instead of scaling to 20 Nodes, it is able to scale 20% more than the requested, in this case is 24, in this case input value is `0.2` (Optional)
 
 **Trigger Authentication**
 - `username` - Username for basic authentication in GraphQL endpoint instead of embedding in the URL. (Optional)
 - `password` - Password for basic authentication in GraphQL endpoint instead of embedding in the URL. (Optional)
 - `authType` - Type of authentication to be used. This can be set to `Bearer` or `OAuth2` in case Selenium Grid behind an Ingress proxy with other authentication types. (Optional)
 - `accessToken` - Access token. This is required when `authType` is set a value. (Optional)
 
+Noted that trigger authentication parameters are able to set in either trigger metadata or trigger authentication. However, if both are set, the trigger authentication will take precedence.
+
 ### Example
 
 ---

.keda/scalers/selenium_grid_scaler.go

@@ -28,22 +28,22 @@ type seleniumGridScaler struct {
 type seleniumGridScalerMetadata struct {
 	triggerIndex int
 
-	URL                    string `keda:"name=url,                      order=authParams;triggerMetadata"`
-	AuthType               string `keda:"name=authType,                 order=authParams;resolvedEnv, optional"`
-	Username               string `keda:"name=username,                 order=authParams;resolvedEnv, optional"`
-	Password               string `keda:"name=password,                 order=authParams;resolvedEnv, optional"`
-	AccessToken            string `keda:"name=accessToken,              order=authParams;resolvedEnv, optional"`
-	BrowserName            string `keda:"name=browserName,              order=triggerMetadata, optional"`
-	SessionBrowserName     string `keda:"name=sessionBrowserName,       order=triggerMetadata, optional"`
-	BrowserVersion         string `keda:"name=browserVersion,           order=triggerMetadata, optional"`
-	PlatformName           string `keda:"name=platformName,             order=triggerMetadata, optional"`
-	ActivationThreshold    int64  `keda:"name=activationThreshold,      order=triggerMetadata, optional"`
-	UnsafeSsl              bool   `keda:"name=unsafeSsl,                order=triggerMetadata, default=false"`
-	NodeMaxSessions        int64  `keda:"name=nodeMaxSessions,          order=triggerMetadata, default=1"`
-	EnableManagedDownloads bool   `keda:"name=enableManagedDownloads,   order=triggerMetadata, default=true"`
-	Capabilities           string `keda:"name=capabilities,             order=triggerMetadata, optional"`
-
-	TargetValue int64
+	URL                    string  `keda:"name=url,                      order=authParams;triggerMetadata;resolvedEnv"`
+	AuthType               string  `keda:"name=authType,                 order=authParams;triggerMetadata;resolvedEnv, optional"`
+	Username               string  `keda:"name=username,                 order=authParams;triggerMetadata;resolvedEnv, optional"`
+	Password               string  `keda:"name=password,                 order=authParams;triggerMetadata;resolvedEnv, optional"`
+	AccessToken            string  `keda:"name=accessToken,              order=authParams;triggerMetadata;resolvedEnv, optional"`
+	BrowserName            string  `keda:"name=browserName,              order=triggerMetadata, optional"`
+	SessionBrowserName     string  `keda:"name=sessionBrowserName,       order=triggerMetadata, optional"`
+	BrowserVersion         string  `keda:"name=browserVersion,           order=triggerMetadata, optional"`
+	PlatformName           string  `keda:"name=platformName,             order=triggerMetadata, optional"`
+	NodeMaxSessions        int64   `keda:"name=nodeMaxSessions,          order=triggerMetadata, default=1"`
+	EnableManagedDownloads bool    `keda:"name=enableManagedDownloads,   order=triggerMetadata, default=true"`
+	Capabilities           string  `keda:"name=capabilities,             order=triggerMetadata, optional"`
+	OverProvisionRatio     float64 `keda:"name=overProvisionRatio,       order=triggerMetadata, optional"`
+	UnsafeSsl              bool    `keda:"name=unsafeSsl,                order=triggerMetadata, optional"`
+	TargetValue            int64   `keda:"name=targetValue,              order=triggerMetadata, default=1"`
+	ActivationThreshold    float64 `keda:"name=activationThreshold,      order=triggerMetadata, optional"`
 }
 
 type Platform struct {
@@ -173,12 +173,10 @@ func parseCapabilitiesToMap(_capabilities string) (map[string]interface{}, error
 }
 
 func parseSeleniumGridScalerMetadata(config *scalersconfig.ScalerConfig) (*seleniumGridScalerMetadata, error) {
-	meta := &seleniumGridScalerMetadata{
-		TargetValue: 1,
-	}
+	meta := &seleniumGridScalerMetadata{}
 
 	if err := config.TypedConfig(meta); err != nil {
-		return nil, fmt.Errorf("error parsing prometheus metadata: %w", err)
+		return nil, fmt.Errorf("error parsing Selenium Grid GraphQL response: %w", err)
 	}
 
 	meta.triggerIndex = config.TriggerIndex
@@ -204,9 +202,19 @@ func (s *seleniumGridScaler) GetMetricsAndActivity(ctx context.Context, metricNa
 		return []external_metrics.ExternalMetricValue{}, false, fmt.Errorf("error requesting selenium grid endpoint: %w", err)
 	}
 
-	metric := GenerateMetricInMili(metricName, float64(newRequestNodes+onGoingSessions))
+	scaledCount := getScaledCount(newRequestNodes, onGoingSessions, s.metadata.OverProvisionRatio)
+	metric := GenerateMetricInMili(metricName, scaledCount)
+
+	return []external_metrics.ExternalMetricValue{metric}, scaledCount > s.metadata.ActivationThreshold, nil
+}
 
-	return []external_metrics.ExternalMetricValue{metric}, (newRequestNodes + onGoingSessions) > s.metadata.ActivationThreshold, nil
+func getScaledCount(newRequestNodes int64, onGoingSession int64, overProvisionRatio float64) float64 {
+	scaledCount := float64(newRequestNodes + onGoingSession)
+	if overProvisionRatio > 0 {
+		// Apply over-provision ratio to the scaled count
+		scaledCount += scaledCount * overProvisionRatio
+	}
+	return scaledCount
 }
 
 func buildSeleniumGridMetricName(meta *seleniumGridScalerMetadata) string {

.keda/scalers/selenium_grid_scaler_test.go

@@ -19,12 +19,14 @@ func Test_getCountFromSeleniumResponse(t *testing.T) {
 		nodeMaxSessions        int64
 		enableManagedDownloads bool
 		capabilities           string
+		overProvisionRatio     float64
 	}
 	tests := []struct {
 		name                string
 		args                args
 		wantNewRequestNodes int64
 		wantOnGoingSessions int64
+		wantOverProvisioned float64
 		wantErr             bool
 	}{
 		{
@@ -437,6 +439,57 @@ func Test_getCountFromSeleniumResponse(t *testing.T) {
 			wantOnGoingSessions: 0,
 			wantErr:             false,
 		},
+		{
+			name: "Scaled_number_when_set_param_over_provisioned",
+			args: args{
+				b: []byte(`{
+                    "data": {
+                        "grid": {
+                            "sessionCount": 0,
+                            "maxSession": 0,
+                            "totalSlots": 0
+                        },
+                        "nodesInfo": {
+                            "nodes": [
+                                {
+                                    "id": "node-1",
+                                    "status": "UP",
+                                    "sessionCount": 0,
+                                    "maxSession": 1,
+                                    "slotCount": 1,
+                                    "stereotypes": "[{\"slots\": 1, \"stereotype\": {\"browserName\": \"chrome\", \"browserVersion\": \"\", \"platformName\": \"linux\"}}]",
+                                    "sessions": []
+                                },
+                                {
+                                    "id": "node-2",
+                                    "status": "UP",
+                                    "sessionCount": 0,
+                                    "maxSession": 1,
+                                    "slotCount": 1,
+                                    "stereotypes": "[{\"slots\": 1, \"stereotype\": {\"browserName\": \"chrome\", \"browserVersion\": \"\", \"platformName\": \"Windows 11\"}}]",
+                                    "sessions": []
+                                }
+                            ]
+                        },
+                        "sessionsInfo": {
+                            "sessionQueueRequests": [
+                                "{\"browserName\": \"chrome\", \"platformName\": \"linux\"}",
+                                "{\"browserName\": \"chrome\", \"platformName\": \"linux\"}"
+                            ]
+                        }
+                    }
+                }`),
+				browserName:        "chrome",
+				sessionBrowserName: "chrome",
+				browserVersion:     "",
+				platformName:       "linux",
+				overProvisionRatio: 1.2,
+			},
+			wantNewRequestNodes: 1,
+			wantOnGoingSessions: 0,
+			wantOverProvisioned: 2.2,
+			wantErr:             false,
+		},
 		{
 			name: "scaler_browserVersion_is_latest,_5_sessionQueueRequests_wihtout_browserVersion_also_1_different_platformName,_1_available_nodeStereotypes_with_3_slots_Linux_and_1_node_Windows,_should_return_count_as_1",
 			args: args{
@@ -1048,7 +1101,7 @@ func Test_getCountFromSeleniumResponse(t *testing.T) {
 			wantErr:             false,
 		},
 		{
-			name: "1 queue request without platformName and scaler metadata without platfromName should return 1 new node and 1 ongoing session",
+			name: "1 queue request without platformName and scaler metadata without platformName should return 1 new node and 1 ongoing session",
 			args: args{
 				b: []byte(`{
 					"data": {
@@ -3154,13 +3207,17 @@ func Test_getCountFromSeleniumResponse(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			newRequestNodes, onGoingSessions, err := getCountFromSeleniumResponse(tt.args.b, tt.args.browserName, tt.args.browserVersion, tt.args.sessionBrowserName, tt.args.platformName, tt.args.nodeMaxSessions, tt.args.enableManagedDownloads, tt.args.capabilities, logr.Discard())
+			scaledCount := getScaledCount(newRequestNodes, onGoingSessions, tt.args.overProvisionRatio)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("getCountFromSeleniumResponse() error = %v, wantErr %v", err, tt.wantErr)
 				return
 			}
 			if !reflect.DeepEqual(newRequestNodes, tt.wantNewRequestNodes) || !reflect.DeepEqual(onGoingSessions, tt.wantOnGoingSessions) {
 				t.Errorf("getCountFromSeleniumResponse() = [%v, %v], want [%v, %v]", newRequestNodes, onGoingSessions, tt.wantNewRequestNodes, tt.wantOnGoingSessions)
 			}
+			if tt.args.overProvisionRatio > 0 && !reflect.DeepEqual(scaledCount, tt.wantOverProvisioned) {
+				t.Errorf("getCountFromSeleniumResponse() = %v, want over-provisioned %v", scaledCount, tt.wantOverProvisioned)
+			}
 		})
 	}
 }

Makefile

@@ -34,8 +34,8 @@ KEDA_TAG_PREV_VERSION := $(or $(KEDA_TAG_PREV_VERSION),$(KEDA_TAG_PREV_VERSION),
 KEDA_CORE_VERSION := $(or $(KEDA_CORE_VERSION),$(KEDA_CORE_VERSION),2.17.2)
 KEDA_TAG_VERSION := $(or $(KEDA_TAG_VERSION),$(KEDA_TAG_VERSION),2.17.2-selenium-grid)
 KEDA_BASED_NAME := $(or $(KEDA_BASED_NAME),$(KEDA_BASED_NAME),ndviet)
-KEDA_BASED_TAG := $(or $(KEDA_BASED_TAG),$(KEDA_BASED_TAG),2.17.2-selenium-grid-20250705)
-TEST_PATCHED_KEDA := $(or $(TEST_PATCHED_KEDA),$(TEST_PATCHED_KEDA),false)
+KEDA_BASED_TAG := $(or $(KEDA_BASED_TAG),$(KEDA_BASED_TAG),2.17.2-selenium-grid-20250721)
+TEST_PATCHED_KEDA := $(or $(TEST_PATCHED_KEDA),$(TEST_PATCHED_KEDA),true)
 
 all: hub \
 	distributor \
@@ -284,7 +284,7 @@ fetch_grid_scaler_resources:
 	&& cd ./.keda/scalers \
 	&& curl -L https://raw.githubusercontent.com/$(KEDA_BASED_NAME)/keda/v$(KEDA_BASED_TAG)/pkg/scalers/selenium_grid_scaler.go -o selenium_grid_scaler.go \
 	&& curl -L https://raw.githubusercontent.com/$(KEDA_BASED_NAME)/keda/v$(KEDA_BASED_TAG)/pkg/scalers/selenium_grid_scaler_test.go -o selenium_grid_scaler_test.go \
-	&& curl -L https://raw.githubusercontent.com/$(KEDA_BASED_NAME)/keda-docs/main/content/docs/2.17/scalers/selenium-grid-scaler.md -o selenium-grid-scaler.md
+	&& curl -L https://raw.githubusercontent.com/$(KEDA_BASED_NAME)/keda-docs/main/content/docs/2.18/scalers/selenium-grid-scaler.md -o selenium-grid-scaler.md
 
 fetch_grid_scaler_images:
 	docker pull --platform linux/amd64 --platform linux/arm64 $(KEDA_BASED_NAME)/keda:$(KEDA_BASED_TAG)