Experimental: Selenium Grid scaler in K8s implementation preview (#2400)

.github/workflows/deploy.yml

@@ -152,7 +152,9 @@ jobs:
           continue_on_error: true
           command: VERSION="${GRID_VERSION}" BUILD_DATE=${BUILD_DATE} make release_latest
       - name: Update package versions
-        run: make generate_latest_sbom
+        run: |
+          make generate_latest_sbom
+          make fetch_grid_scaler_resources
       - name: Tag browser images
         if: github.event.inputs.skip-build-push-image != 'true'
         uses: nick-invision/retry@master

.keda/README.md

@@ -0,0 +1,62 @@
+# Introduction
+
+Selenium Grid Scaler is a built-in scaler is maintained in upstream KEDA [repository](https://github.com/kedacore/keda). The scaler implementation could be found [here](https://github.com/kedacore/keda/blob/main/pkg/scalers/selenium_grid_scaler.go). The official docs of the scaler could be seen [here](https://keda.sh/docs/latest/scalers/selenium-grid-scaler/).
+
+Now, [SeleniumHQ/docker-selenium](https://github.com/SeleniumHQ/docker-selenium) involves as the maintainer for the scaler.
+
+In order to deliver and get feedback continuously on any new bug fixes, improvement, or features for the Selenium Grid scaler. We select the latest stable version of KEDA core, patch the scaler implementation then build and deploy KEDA container images following our image tag convention.
+
+The stable implementation will be merged to the upstream KEDA repository frequently and will be available in the next KEDA core release.
+
+# How to use the patched scaler
+
+Replace the image registry and tag of these KEDA components with the patched image tag:
+
+```bash
+docker pull selenium/keda:2.15.1-selenium-grid-20240907
+docker pull selenium/keda-metrics-apiserver:2.15.1-selenium-grid-20240907
+docker pull selenium/keda-admission-webhooks:2.15.1-selenium-grid-20240907
+```
+
+Besides that, you also can use image tag `latest` or `nightly`.
+
+If you are deploying KEDA core using their official Helm chart, you can overwrite the image registry and tag by providing the following values in the `values.yaml` file. For example:
+
+```yaml
+  image:
+    keda:
+      registry: selenium
+      repository: keda
+      tag: "2.15.1-selenium-grid-20240907"
+    metricsApiServer:
+      registry: selenium
+      repository: keda-metrics-apiserver
+      tag: "2.15.1-selenium-grid-20240907"
+    webhooks:
+      registry: selenium
+      repository: keda-admission-webhooks
+      tag: "2.15.1-selenium-grid-20240907"
+```
+
+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).
+
+# Pull requests under testing
+
+Here is list of pull requests that are under testing and will be merged to the upstream KEDA repository.
+You can involve to review and discuss the pull requests to help us early detect and fix any issues.
+
+[kedacore/keda](https://github.com/kedacore/keda)
+
+- https://github.com/kedacore/keda/pull/6169
+
+[kedacore/keda-docs](https://github.com/kedacore/keda-docs)
+
+- https://github.com/kedacore/keda-docs/pull/1468
+
+# Resources
+
+You can inspect the implementation of current Selenium Grid scaler:
+
+- [selenium_grid_scaler.go](./scalers/selenium_grid_scaler.go)
+- [selenium_grid_scaler_test.go](./scalers/selenium_grid_scaler_test.go)
+- [selenium-grid-scaler.md](./scalers/selenium-grid-scaler.md)

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

@@ -0,0 +1,207 @@
++++
+title = "Selenium Grid Scaler"
+availability = "v2.4+"
+maintainer = "Volvo Cars, SeleniumHQ"
+category = "Testing"
+description = "Scales Selenium browser nodes based on number of requests waiting in session queue"
+go_file = "selenium_grid_scaler"
++++
+
+### Trigger Specification
+
+This specification describes the `selenium-grid` trigger that scales browser nodes based on number of requests in session queue and the max sessions per grid.
+
+The scaler creates one browser node per pending request in session queue, divided by the max amount of sessions that can run in parallel. You will have to create one trigger per browser capability that you would like to support in your Selenium Grid.
+
+The below is an example trigger configuration for chrome node.
+
+```yaml
+triggers:
+  - type: selenium-grid
+    metadata:
+      url: 'http://selenium-hub:4444/graphql' # Required. Can be ommitted if specified via TriggerAuthentication/ClusterTriggerAuthentication.
+      browserName: 'chrome'  # Required
+      browserVersion: '91.0' # Optional. Only required when supporting multiple versions of browser in your Selenium Grid.
+      unsafeSsl : 'true' # Optional
+      activationThreshold: 5 # Optional
+      platformName: 'Linux' # Optional
+```
+
+**Parameter list:**
+
+- `url` - Graphql url of your Selenium Grid. Refer to the Selenium Grid's documentation [here](https://www.selenium.dev/documentation/en/grid/grid_4/graphql_support/) to for more info.
+- `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)
+- `browserName` - Name of browser that usually gets passed in the browser capability. Refer to the [Selenium Grid's](https://www.selenium.dev/documentation/en/getting_started_with_webdriver/browsers/) and [WebdriverIO's](https://webdriver.io/docs/options/#capabilities) documentation for more info.
+- `sessionBrowserName` -  Name of the browser when it is an active session, only set if `BrowserName` changes between the queue and the active session. See the Edge example below for further detail. (Optional)
+- `browserVersion` - Version of browser that usually gets passed in the browser capability. Refer to the [Selenium Grid's](https://www.selenium.dev/documentation/en/getting_started_with_webdriver/browsers/) and [WebdriverIO's](https://webdriver.io/docs/options/#capabilities) documentation for more info. (Optional)
+- `unsafeSsl` - Skip certificate validation when connecting over HTTPS. (Values: `true`, `false`, Default: `false`, Optional)
+- `activationThreshold` - Target value for activating the scaler. Learn more about activation [here](./../concepts/scaling-deployments.md#activating-and-scaling-thresholds). (Default: `0`, Optional)
+- `platformName` - Name of the browser platform. Refer to the [Selenium Grid's](https://www.selenium.dev/documentation/en/getting_started_with_webdriver/browsers/) and [WebdriverIO's](https://webdriver.io/docs/options/#capabilities) documentation for more info. (Default: `Linux`, Optional)
+- `nodeMaxSessions` - Number of maximum sessions that can run in parallel on a Node. (Default: `1`, Optional). Update this parameter align with node config `--max-sessions` (`SE_NODE_MAX_SESSIONS`) to have the correct scaling behavior.
+
+### Example
+
+Here is a full example of scaled object definition using Selenium Grid trigger:
+
+```yaml
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: selenium-grid-chrome-scaledobject
+  namespace: keda
+  labels:
+    deploymentName: selenium-chrome-node
+spec:
+  maxReplicaCount: 8
+  scaleTargetRef:
+    name: selenium-chrome-node
+  triggers:
+    - type: selenium-grid
+      metadata:
+        url: 'http://selenium-hub:4444/graphql'
+        browserName: 'chrome'
+```
+
+The above example will create Chrome browser nodes equal to the requests pending in session queue for Chrome browser.
+
+Similarly for Firefox
+
+```yaml
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: selenium-grid-firefox-scaledobject
+  namespace: keda
+  labels:
+    deploymentName: selenium-firefox-node
+spec:
+  maxReplicaCount: 8
+  scaleTargetRef:
+    name: selenium-firefox-node
+  triggers:
+    - type: selenium-grid
+      metadata:
+        url: 'http://selenium-hub:4444/graphql'
+        browserName: 'firefox'
+```
+
+Similarly for Edge. Note that for Edge you must set the `sessionBrowserName` to `msedge` inorder for scaling to work properly.
+
+```yaml
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: selenium-grid-edge-scaledobject
+  namespace: keda
+  labels:
+    deploymentName: selenium-edge-node
+spec:
+  maxReplicaCount: 8
+  scaleTargetRef:
+    name: selenium-edge-node
+  triggers:
+    - type: selenium-grid
+      metadata:
+        url: 'http://selenium-hub:4444/graphql'
+        browserName: 'MicrosoftEdge'
+        sessionBrowserName: 'msedge'
+```
+
+If you are supporting multiple versions of browser capability in your Selenium Grid, You should create one scaler for every browser version and pass the `browserVersion` in the metadata.
+
+```yaml
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: selenium-grid-chrome-91-scaledobject
+  namespace: keda
+  labels:
+    deploymentName: selenium-chrome-node-91
+spec:
+  maxReplicaCount: 8
+  scaleTargetRef:
+    name: selenium-chrome-node-91
+  triggers:
+    - type: selenium-grid
+      metadata:
+        url: 'http://selenium-hub:4444/graphql'
+        browserName: 'chrome'
+        browserVersion: '91.0'
+```
+
+```yaml
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: selenium-grid-chrome-90-scaledobject
+  namespace: keda
+  labels:
+    deploymentName: selenium-chrome-node-90
+spec:
+  maxReplicaCount: 8
+  scaleTargetRef:
+    name: selenium-chrome-node-90
+  triggers:
+    - type: selenium-grid
+      metadata:
+        url: 'http://selenium-hub:4444/graphql'
+        browserName: 'chrome'
+        browserVersion: '90.0'
+```
+
+### Authentication Parameters
+
+It is possible to specify the Graphql url of your Selenium Grid using authentication parameters. This useful if you have enabled Selenium Grid's Basic HTTP Authentication and would like to keep your credentials secure.
+
+- `url` - Graphql url of your Selenium Grid. Refer to the Selenium Grid's documentation [here](https://www.selenium.dev/documentation/en/grid/grid_4/graphql_support/) for more info.
+- `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)
+
+```yaml
+apiVersion: v1
+kind: Secret
+metadata:
+  name: selenium-grid-secret
+  namespace: keda
+type: Opaque
+data:
+  graphql-url: base64 encoded value of GraphQL URL
+  graphql-username: base64 encoded value of GraphQL Username
+  graphql-password: base64 encoded value of GraphQL Password
+---
+apiVersion: keda.sh/v1alpha1
+kind: TriggerAuthentication
+metadata:
+  name: keda-trigger-auth-selenium-grid-secret
+  namespace: keda
+spec:
+  secretTargetRef:
+  - parameter: url
+    name: selenium-grid-secret
+    key: graphql-url
+  - parameter: username
+    name: selenium-grid-secret
+    key: graphql-username
+  - parameter: password
+    name: selenium-grid-secret
+    key: graphql-password
+---
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: selenium-grid-chrome-scaledobject
+  namespace: keda
+  labels:
+    deploymentName: selenium-chrome-node
+spec:
+  maxReplicaCount: 8
+  scaleTargetRef:
+    name: selenium-chrome-node
+  triggers:
+    - type: selenium-grid
+      metadata:
+        browserName: 'chrome'
+      authenticationRef:
+        name: keda-trigger-auth-selenium-grid-secret
+```