Prometheus Metrics exposed from operator (#989)

* Prometheus Metrics exposed from operator

Signed-off-by: Zbynek Roubalik <zroubalik@gmail.com>

* sort

Signed-off-by: Zbynek Roubalik <zroubalik@gmail.com>

* sort 2

Signed-off-by: Zbynek Roubalik <zroubalik@gmail.com>

Signed-off-by: Zbynek Roubalik <zroubalik@gmail.com>

content/docs/2.9/operate/prometheus.md

@@ -6,15 +6,21 @@ weight = 200
 
 ## Prometheus Exporter Metrics
 
-### Operator 
+### KEDA Operator 
 
 The KEDA Operator exposes Prometheus metrics which can be scraped on port `8080` at `/metrics`. The following metrics are being gathered:
 
-- `keda_operator_resource_totals` - Total number of KEDA custom resources per namespace for each custom resource type (CRD).
-- `keda_operator_trigger_totals` - Total number of triggers per trigger type.
+- `keda_scaler_metrics_value`- The current value for each scaler's metric that would be used by the HPA in computing the target average.
+- `keda_scaler_errors` - The number of errors that have occurred for each scaler.
+- `keda_scaler_error_totals` - The total number of errors encountered for all scalers.
+- `keda_scaled_object_error_totals`- The number of errors that have occurred for each ScaledObejct.
+- `keda_resource_totals` - Total number of KEDA custom resources per namespace for each custom resource type (CRD).
+- `keda_trigger_totals` - Total number of triggers per trigger type.
 - Metrics exposed by the `Operator SDK` framework as explained [here](https://sdk.operatorframework.io/docs/building-operators/golang/advanced-topics/#metrics).
 
-### Metrics Adapter
+### Metrics Server
+
+> 💡 **DEPRECATED:** Prometheus Metrics exposed from Metrics Server are deprecated, please consume metrics from KEDA Operator.
 
 The KEDA Metrics Adapter exposes Prometheus metrics which can be scraped on port `9022` (this can be changed by setting the `metrics-port` argument for the Metrics Adapter) at `/metrics`.  The metrics collected in the Metrics Adapter are only active when the HPA is active (> 0 replicas).