Update RabbitMQ Scaler documentation to include the option of use reg…

…ex (#489)

* Update RabbitMQ Scaler documentation to include the option of use regex in case of http queue

Signed-off-by: jorturfer <[email protected]>

* Update the documentation with the suggestions

Signed-off-by: jorturfer <[email protected]>

Co-authored-by: Tom Kerkhove <[email protected]>
Signed-off-by: Jorge Turrado <[email protected]>

* Improve documentation

Co-authored-by: Zbynek Roubalik <[email protected]>
Signed-off-by: jorturfer <[email protected]>

* Remove whitespaces

Signed-off-by: jorturfer <[email protected]>

* Clarify possible values to useRegex

Signed-off-by: jorturfer <[email protected]>

* Update documentation to allow regex + messageRate

Signed-off-by: Jorge Turrado <[email protected]>

Co-authored-by: Tom Kerkhove <[email protected]>
Co-authored-by: Zbynek Roubalik <[email protected]>

content/docs/2.4/scalers/rabbitmq-queue.md

@@ -37,6 +37,8 @@ triggers:
 - `protocol`: Protocol to be used for communication. Either `auto`, `http`, or `amqp`. It should correspond with the `host` value. Optional, will autodetect based on the `host` URL if possible.
 - `vhostName`: Vhost to use for the connection, overrides any vhost set in the connection string from `host`/`hostFromEnv`.
 - `queueLength`: DEPRECATED! Use `mode: QueueLength` and `value: ##` instead. Target value for queue length passed to the scaler. Example: if one pod can handle 10 messages, set the queue length target to 10. If the actual number of messages in the queue is 30, the scaler scales to 3 pods. Default is 20 unless `publishRate` is specified, in which case `queueLength` is disabled for this trigger.
+- `useRegex`: In case of `http` protocol, this parameter allows to use regex (in `queueName` parameter) to select queue instead of full name, the valid values are: `"true"` and `"false"`.  Optional.
+- `operation`: Operation that will be applied to compute the number of messages in case of `useRegex` enabled. Either `sum` (default),`max`, or `avg`. Optional.
 
 Some parameters could be provided using environmental variables, instead of setting them directly in metadata. Here is a list of parameters you can use to retrieve values from environment variables:
 
@@ -46,6 +48,8 @@ Some parameters could be provided using environmental variables, instead of sett
 
 > 💡 **Note:** `mode: MessageRate` requires protocol `http`.
 
+> 💡 **Note:** `useRegex: "true"` requires protocol `http` and ignores unacknowledged messages.
+
 > ⚠ **Important:** if you have unacknowledged messages and want to have these counted for the scaling to happen, make sure to utilize the `http` REST API interface which allows for these to be counted.
 
 > ⚠ **Important:** If scaling against both is desired then the `ScaledObject` should have two triggers, one for `mode: QueueLength` and the other for `mode: MessageRate`. HPA will scale based on the largest result considering each of the two triggers independently.
@@ -188,3 +192,45 @@ spec:
     authenticationRef:
       name: keda-trigger-auth-rabbitmq-conn
 ```
+
+#### HTTP protocol (`QueueLength`) and using regex (`useRegex`):
+
+```yaml
+apiVersion: v1
+kind: Secret
+metadata:
+  name: keda-rabbitmq-secret
+data:
+  host: <HTTP API endpoint> # base64 encoded value of format http://guest:password@localhost:15672/vhost
+---
+apiVersion: keda.sh/v1alpha1
+kind: TriggerAuthentication
+metadata:
+  name: keda-trigger-auth-rabbitmq-conn
+  namespace: default
+spec:
+  secretTargetRef:
+    - parameter: host
+      name: keda-rabbitmq-secret
+      key: host
+---
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: rabbitmq-scaledobject
+  namespace: default
+spec:
+  scaleTargetRef:
+    name: rabbitmq-deployment
+  triggers:
+  - type: rabbitmq
+    metadata:
+      protocol: http
+      queueName: ^.*incoming$
+      mode: QueueLength
+      value: "20"
+      useRegex: "true"
+      operation: max
+    authenticationRef:
+      name: keda-trigger-auth-rabbitmq-conn
+```