Add Dynatrace scaler docs

content/docs/2.15/scalers/dynatrace.md

@@ -0,0 +1,93 @@
++++
+title = "Dynatrace"
+availability = "2.15+"
+maintainer = "Community"
+description = "Scale applications based on Dynatrace metric data points"
+go_file = "dynatrace_scaler"
++++
+
+### Trigger Specification
+
+This specification describes the `dynatrace` trigger that scales based on Dynatrace metric data points.
+
+```yaml
+triggers:
+  - type: dynatrace
+    metadata:
+      host: https://dummy-instance.live.dynatrace.com/
+      metricSelector: 'MyCustomEvent:filter(eq("someProperty","someValue")):count:splitBy("dt.entity.process_group"):fold'
+      # Optional
+      from: now-2d
+      threshold: "10"
+      # Optional
+      activationThreshold: "5"
+```
+
+**Parameter list:**
+
+- `host` - The Dynatrace instance to query against
+- `token` - The API key that will be leveraged to connect to Dynatrace and make requests ([official documentation](https://docs.dynatrace.com/docs/dynatrace-api/basics/dynatrace-api-authentication)). Requires the `metrics.read` scope. Must be provided via Trigger Authentication (see [Authentication Parameters](#authentication-parameters))
+- `metricSelector` - The metric selector query and any transformations that should be applied to it ([transformations docs](https://docs.dynatrace.com/docs/dynatrace-api/environment-api/metric-v2/metric-selector)).
+
+  Some relevant aspects:
+    - The selector should focus on a **single metric and dimension**: if multiple are found, a warning is issued and only the first one is considered
+    - The metric data points should be aggregated to produce a single output value (e.g., using the [fold transformation](https://docs.dynatrace.com/docs/shortlink/api-metrics-v2-selector#fold)): if multiple values are found, only the first one is considered
+    - If you need to use the entity selector, do it through the `:filter` transformation in the metric selector
+- `from` - How far back the metric selector should consider when fetching data points. [syntax supported](https://docs.dynatrace.com/docs/dynatrace-api/environment-api/metric-v2/get-data-points#parameters). (Optional, default `now-2h`, i.e., the last 2 hours)
+- `threshold` - A threshold that is used as the `targetValue` or `targetAverageValue` (depending on the trigger metric type) in the HPA configuration. (This value can be a float)
+- `activationThreshold` - Target value for activating the scaler. Learn more about activation [here](./../concepts/scaling-deployments.md#activating-and-scaling-thresholds). (Optional, default `0`, can be a float)
+
+### Authentication Parameters
+
+You can use `TriggerAuthentication` CRD to configure authentication the `host` and `token` parameters.
+
+**Authentication:**
+
+- `host` - The Dynatrace instance to query against
+- `token` - The API key that will be leveraged to connect to Dynatrace and make requests ([official documentation](https://docs.dynatrace.com/docs/dynatrace-api/basics/dynatrace-api-authentication)). Requires the `metrics.read` scope
+
+### Example
+
+```yaml
+apiVersion: v1
+kind: Secret
+metadata:
+  name: dynatrace-secret
+  namespace: my-project
+type: Opaque
+data:
+  host: aHR0cHM6Ly9kdW1teS1pbnN0YW5jZS5saXZlLmR5bmF0cmFjZS5jb20vCg== # base64 encoding of https://dummy-instance.live.dynatrace.com/
+  token: ZHQwczAxLlNUMkVZNzJLUUlOTUg1NzRXTU5WSTdZTi5HM0RGUEJFSllNT0RJREFFWDQ1NE03WVdCVVZFRk9XS1BSVk1XRkFTUzY0TkZINTJQWDZCTkRWRkZNNTcyUlpNCg== # base64 encoding of the dynatrace example api key dt0s01.ST2EY72KQINMH574WMNVI7YN.G3DFPBEJYMODIDAEX454M7YWBUVEFOWKPRVMWFASS64NFH52PX6BNDVFFM572RZM
+---
+apiVersion: keda.sh/v1alpha1
+kind: TriggerAuthentication
+metadata:
+  name: keda-trigger-auth-dynatrace
+  namespace: my-project
+spec:
+  secretTargetRef:
+  - parameter: token
+    name: dynatrace-secret
+    key: token
+  - parameter: host
+    name: dynatrace-secret
+    key: host
+---
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: dynatrace-scaledobject
+  namespace: keda
+spec:
+  maxReplicaCount: 12
+  scaleTargetRef:
+    name: dummy
+  triggers:
+    - type: dynatrace
+      metadata:
+        metricSelector: 'MyCustomEvent:filter(eq("someProperty","someValue")):count:splitBy("dt.entity.process_group"):fold'
+        from: 'now-30m'
+        threshold: '1000'
+      authenticationRef:
+        name: keda-trigger-auth-dynatrace
+```