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Search transform

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Search transform

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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 66. 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

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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"
            }
          }
        }
      }
    }
  }
}

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