docs: Provide New Relic scaler (kedacore#591)

Signed-off-by: Joshua Jackson <[email protected]>

content/docs/2.6/scalers/new-relic.md

@@ -0,0 +1,92 @@
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+title = "New Relic"
+availability = "2.6+"
+maintainer = "Community"
+description = "Scale applications based on New Relic NRQL"
+layout = "scaler"
+go_file = "newrelic_scaler"
++++
+
+### Trigger Specification
+
+This specification describes the `new-relic` trigger that scales based on a New Relic metric.
+
+```yaml
+triggers:
+  - type: new-relic
+    metadata:
+      # Required: Account - Subaccount to run the query on
+      account: 1234567
+      # Required: QueryKey - Api key to connect to New Relic
+      queryKey: "NRAK-xxxxxxxxxxxxxxxxxxxxxxxxxxx"
+      # Optional: nrRegion - Region to query data for. Default value is US.
+      region: "US"
+      # Optional: noDataError - If the query returns no data should this be treated as an error. Default value is false.
+      noDataError: "true"
+      # Required: nrql
+      nrql: "SELECT average(duration) from Transaction where appName='SITE' TIMESERIES"
+      # Required: threshold
+      threshold: 100
+```
+
+**Parameter list:**
+
+- `account` - The account within New Relic that the request should be targeted against.
+- `queryKey` - The API key that will be leveraged to connect to New Relic and make requests. [official documentation](https://docs.newrelic.com/docs/apis/intro-apis/new-relic-api-keys/)
+- `region` - The region to connect to for the New Relic apis. (Values: `LOCAL`, `EU`, `STAGING`, `US`, Default: `US`, Optional)
+- `noDataError` - Should queries that return nodata be treated as an error (Values: `true`, `false`, Default: `false`, Optional)
+- `nrql` - The New Relic query that will be run to get the data requested. [official documentation](https://docs.newrelic.com/docs/query-your-data/nrql-new-relic-query-language/get-started/introduction-nrql-new-relics-query-language/)
+- `threshold` - A threshold that is used as the `targetAverageValue` in the HPA configuration.
+
+### Authentication Parameters
+
+You can use `TriggerAuthentication` CRD to configure the authentication with a `queryKey`.
+
+**Authentication:**
+
+- `queryKey` - The API key that will be leveraged to connect to New Relic and make requests. [official documentation](https://docs.newrelic.com/docs/apis/intro-apis/new-relic-api-keys/)
+
+### Example
+
+```yaml
+apiVersion: v1
+kind: Secret
+metadata:
+  name: new-relic-secret
+  namespace: my-project
+type: Opaque
+data:
+  apiKey: TlJBSy0xMjM0NTY3ODkwMTIzNDU2Nwo= # base64 encoding of the new relic api key NRAK-12345678901234567
+---
+apiVersion: keda.sh/v1alpha1
+kind: TriggerAuthentication
+metadata:
+  name: keda-trigger-auth-new-relic
+  namespace: my-project
+spec:
+  secretTargetRef:
+  - parameter: queryKey
+    name: new-relic-secret
+    key: apiKey
+
+---
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: newrelic-scaledobject
+  namespace: keda
+spec:
+  maxReplicaCount: 12
+  scaleTargetRef:
+    name: dummy
+  triggers:
+    - type: new-relic
+      metadata:
+        account: 1234567
+        region: "US"
+        nrql: "SELECT average(duration) from Transaction where appName='SITE' TIMESERIES"
+        noDataError: "true"
+        threshold: 1000
+        authenticationRef:
+          name: keda-trigger-auth-new-relic
+```