Watch Definition

A watch consists of a trigger, input, condition, and the actions you want to perform when the watch condition is met. In addition, you can define transforms to process the watch payload before executing the actions.

Trigger: Determines when the watch is checked. A watch must have a trigger.
Input: Loads data into the watch payload. If no input is specified, an empty payload is loaded.
Condition: Controls whether the watch actions are executed. If no condition is specified, the condition defaults to always.
Transform: Processes the watch payload to prepare it for the watch actions. You can define transforms at the watch level or define action-specific transforms. Optional.
Actions: Specify what happens when the watch condition is met.

For example, the following snippet shows a Put Watch request that defines a watch that looks for log error events:

PUT _watcher/watch/log_event_watch
{
  "metadata" : { 
    "color" : "red"
  },
  "trigger" : { 
    "schedule" : {
      "interval" : "5m"
    }
  },
  "input" : { 
    "search" : {
      "request" : {
        "indices" : "log-events",
        "body" : {
          "size" : 0,
          "query" : { "match" : { "status" : "error" } }
        }
      }
    }
  },
  "condition" : { 
    "script" : "return ctx.payload.hits.total > 5"
  },
  "transform" : { 
    "search" : {
        "request" : {
          "indices" : "log-events",
          "body" : {
            "query" : { "match" : { "status" : "error" } }
          }
        }
    }
  },
  "actions" : { 
    "my_webhook" : {
      "webhook" : {
        "method" : "POST",
        "host" : "mylisteninghost",
        "port" : 9200,
        "path" : "/{{watch_id}}",
        "body" : "Encountered {{ctx.payload.hits.total}} errors"
      }
    },
    "email_administrator" : {
      "email" : {
        "to" : "sys.admino@host.domain",
        "subject" : "Encountered {{ctx.payload.hits.total}} errors",
        "body" : "Too many error in the system, see attached data",
        "attach_data" : true,
        "priority" : "high"
      }
    }
  }
}

	Metadata - You can attach optional static metadata to a watch.
	Trigger - This schedule trigger executes the watch every 5 minutes
	Input - This input searches for errors in the `log-events` index and loads the response into the watch payload.
	Condition - This condition checks to see if there are more than 5 error events (hits in the search response). If there are, execution continues.
	Transform - If the watch condition is met, this transform loads all of the errors into the watch payload by searching for the errors using the default search type, `query_then_fetch`. All of the watch actions have access to this payload.
	Actions - This watch has two actions. The `my_webhook` action notifies a 3rd party system about the problem. The `email_administrator` action sends a high priority email to the system administrator. The watch payload that contains the errors is attached to the email.

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