Search Transform

A Transform that executes a search on the cluster and replaces the current payload in the watch execution context with the returned search response. The following snippet shows how a simple search transform can be defined on the watch level:

{
  "transform" : {
    "search" : {
      "request" : {
        "body" : { "query" : { "match_all" : {} }}
      }
    }
  }
}

Like every other search based construct, one can make use of the full search API supported by Elasticsearch. For example, the following search transform execute a search over all events indices, matching events with error priority:

{
  "transform" : {
    "search" : {
      "request" : {
        "indices" : [ "events-*" ],
        "body" : {
          "size" : 0,
          "query" : {
            "match" : { "priority" : "error"}
          }
        }
      }
    }
  }
}

The following table lists all available settings for the search transform:

Table 42. Search Transform Settings

Name Required Default Description

request.search_type

no

query_then_fetch

The search type.

request.indices

no

all indices

One or more indices to search on.

request.types

no

all types

One or more document types to search on (may be a comma-delimited string or an array of document types names)

request.body

no

match_all query

The body of the request. The request body follows the same structure you normally send in the body of a REST _search request. The body can be static text or include mustache templates.

request.indices_options.expand_wildcards

no

open

Determines how to expand indices wildcards. Can be one of open, closed, none or all (see multi-index support)

request.indices_options.ignore_unavailable

no

true

A boolean value that determines whether the search should leniently ignore unavailable indices (see multi-index support)

request.indices_options.allow_no_indices

no

true

A boolean value that determines whether the search should leniently return no results when no indices are resolved (see multi-index support)

request.template

no

-

The body of the search template. See configure templates for more information.

timeout

no

30s

The timeout for waiting for the search api call to return. If no response is returned within this time, the search transform times out and fails. This setting overrides the default timeouts.


Template Support

The search transform support mustache templates. This can either be as part of the body definition, or alternatively, point to an existing template (either defined in a file or registered as a script in Elasticsearch).

For example, the following snippet shows a search that refers to the scheduled time of the watch:

{
  "transform" : {
    "search" : {
      "request" : {
        "indices" : [ "logstash-*" ],
        "types" : [ "event" ],
        "body" : {
          "size" : 0,
          "query" : {
            "bool" : {
              "must" : {
                "match" : { "priority" : "error"}
              },
              "filter" : [
                {
                  "range" : {
                    "@timestamp" : {
                      "from" : "{{ctx.trigger.scheduled_time}}||-30s",
                      "to" : "{{ctx.trigger.triggered_time}}"
                    }
                  }
                }
              ]
            }
          }
        }
      }
    }
  }
}

The model of the template is a union between the provided template.params settings and the standard watch execution context model.

The following is an example of using templates that refer to provided parameters:

{
  "transform" : {
    "search" : {
      "request" : {
        "indices" : [ "logstash-*" ],
        "types" : [ "event" ],
        "template" : {
          "source" : {
            "size" : 0,
            "query" : {
              "bool" : {
                "must" : {
                  "match" : { "priority" : "{{priority}}"}
                },
                "filter" : [
                  {
                    "range" : {
                      "@timestamp" : {
                        "from" : "{{ctx.trigger.scheduled_time}}||-30s",
                        "to" : "{{ctx.trigger.triggered_time}}"
                      }
                    }
                  }
                ]
              }
            },
            "params" : {
              "priority" : "error"
            }
          }
        }
      }
    }
  }
}