Support Query at the Elasticsearch scaler

Signed-off-by: rickbrouwer <rickbrouwer@gmail.com>

content/docs/2.16/scalers/elasticsearch.md

@@ -9,9 +9,9 @@ go_file = "elasticsearch_scaler"
 
 ### Trigger Specification
 
-This specification describes the `elasticsearch` trigger that scales based on result of an [elasticsearch search template](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-template.html) query.
+This specification describes the `elasticsearch` trigger that scales based on result of an [elasticsearch search template](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-template.html) query or [elasticsearch query](https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl.html).
 
-The trigger always requires the following information:
+The trigger always requires the following information, but requires either only searchTemplateName **or** only query:
 
 ```yaml
 triggers:
@@ -22,6 +22,7 @@ triggers:
       passwordFromEnv: "ELASTIC_PASSWORD"
       index: "my-index"
       searchTemplateName: "my-search-template-name"
+      query: "my-query"
       parameters: "param1:value1;param2:value2"
       valueLocation: "hits.total.value"
       targetValue: "1.1"
@@ -35,6 +36,7 @@ triggers:
 - `passwordFromEnv` - Environment variable to read the authentication password from to authenticate with the Elasticsearch cluster.
 - `index` - Comma separated list of indexes to run the search template query on.
 - `searchTemplateName` - The search template name to run.
+- `query` - The query to run.
 - `targetValue` - Target value to scale on. When the metric provided by the API is equal or higher to this value, KEDA will start scaling out. When the metric is 0 or less, KEDA will scale down to 0. (This value can be a float)
 - `activationTargetValue` - Target value for activating the scaler. Learn more about activation [here](./../concepts/scaling-deployments.md#activating-and-scaling-thresholds).(Default: `0`, Optional, This value can be a float)
 - `parameters` - Parameters that will be used by the search template. It supports multiples params separated by a semicolon character ( `;` ).
@@ -57,9 +59,9 @@ You can authenticate by using a username/password or apiKey/cloudID if you're us
 - `cloudID` - CloudID to connect with ElasticSearch on Elastic Cloud.
 - `apiKey` - API key to authenticate with ElasticSearch on Elastic Cloud.
 
-### Example
+### Examples
 
-Here is an example of how to deploy a scaled object with the `elasticsearch` scale trigger which uses `TriggerAuthentication`.
+Here is an example of how to deploy a scaled object with the `elasticsearch` scale trigger which uses the search template and `TriggerAuthentication`.
 
 ```yaml
 apiVersion: v1
@@ -100,3 +102,74 @@ spec:
       authenticationRef:
         name: keda-trigger-auth-elasticsearch-secret
 ```
+Here is an example of how to deploy a scaled object with the `elasticsearch` scale trigger which uses `query`. In this example the transactions will be count that the application has to process based on APM.
+
+```yaml
+apiVersion: v1
+kind: Secret
+metadata:
+  name: elasticsearch-secrets
+type: Opaque
+data:
+  password: cGFzc3cwcmQh
+---
+apiVersion: keda.sh/v1alpha1
+kind: TriggerAuthentication
+metadata:
+  name: keda-trigger-auth-elasticsearch-secret
+spec:
+  secretTargetRef:
+  - parameter: password
+    name: elasticsearch-secrets
+    key: password
+---
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: elasticsearch-scaledobject
+spec:
+  scaleTargetRef:
+    name: "deployment-name"
+  triggers:
+    - type: elasticsearch
+      metadata:
+        addresses: "http://localhost:9200"
+        username: "elastic"
+        index: "my-index"
+        query: |
+          {
+            "size": 0,
+            "query": {
+              "bool": {
+                "must": [
+                  {
+                    "term": {
+                      "service.name": "my-application" }
+                  },
+                  {
+                    "term": {
+                      "service.environment": "production" }
+                  },
+                  {
+                    "range": {
+                      "@timestamp": {
+                        "gte": "now-2m",
+                        "lte": "now-1m"
+                      }
+                    }
+                  }
+                ]
+              }
+            },
+            "aggs": {
+              "transaction_count": {
+                "cardinality": {
+                  "field": "transaction.id" }
+              }
+            }
+          }
+        valueLocation: "aggregations.transaction_count.value"
+        targetValue: "1000"
+      authenticationRef:
+        name: keda-trigger-auth-elasticsearch-secret
+```