Added documentation for new selenium grid scaler (kedacore#491)

Signed-off-by: prashanth <[email protected]> Co-authored-by: prashanth <[email protected]> Co-authored-by: Zbynek Roubalik <[email protected]>
hmoravec · Jul 31, 2021 · b29f45e · b29f45e
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+title = "Selenium Grid Scaler"
+availability = "v2.4+"
+maintainer = "Volvo Cars"
+description = "Scales Selenium browser nodes based on number of requests waiting in session queue"
+layout = "scaler"
+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.
+
+The scaler creates one browser node per pending request in session queue. 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
+      browserName: 'chrome'  # Required
+      browserVersion: '91.0' # Optional. Only required when supporting multiple versions of browser in your Selenium Grid.
+```
+
+**Parameter list:**
+
+- `url` is 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.
+- `browserName` is the 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.
+- `browserVersion` is the version of browser that usually gets passed in the browser capability. This is an optional param and you can ignore it if you are running only one single version of every 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.
+
+### 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.
+
+Similary 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'
+```
+
+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'
+```