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Elastic Docs ›Elasticsearch Guide [7.6] ›Alerting on cluster and index events ›Inputs

Search input

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Search input

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Use the search input to load the results of an Elasticsearch search request into the execution context when the watch is triggered. See Search Input Attributes for all of the supported attributes.

In the search input’s request object, you specify:

  • The indices you want to search
  • The search type
  • The search request body

The search request body supports the full Elasticsearch Query DSL—​it’s the same as the body of an Elasticsearch _search request.

For example, the following input retrieves all event documents from the logs index:

"input" : {
  "search" : {
    "request" : {
      "indices" : [ "logs" ],
      "body" : {
        "query" : { "match_all" : {}}
      }
    }
  }
}

You can use date math and wildcards when specifying indices. For example, the following input loads the latest VIXZ quote from today’s daily quotes index:

{
  "input" : {
    "search" : {
      "request" : {
        "indices" : [ "<stock-quotes-{now/d}>" ],
        "body" : {
          "size" : 1,
          "sort" : {
            "timestamp" : { "order" : "desc"}
          },
          "query" : {
            "term" : { "symbol" : "vix"}
          }
        }
      }
    }
  }
}

Extracting specific fields

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You can specify which fields in the search response you want to load into the watch payload with the extract attribute. This is useful when a search generates a large response and you are only interested in particular fields.

For example, the following input loads only the total number of hits into the watch payload:

"input": {
    "search": {
      "request": {
        "indices": [ ".watcher-history*" ]
      },
      "extract": [ "hits.total.value" ]
    }
  },

Using Templates

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The search input supports search templates. For example, the following snippet references the indexed template called my_template and passes a value of 23 to fill in the template’s value parameter:

{
  "input" : {
    "search" : {
      "request" : {
        "indices" : [ "logs" ],
        "template" : {
          "id" : "my_template",
          "params" : {
            "value" : 23
          }
        }
      }
    }
  }
  ...
}

Applying conditions

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The search input is often used in conjunction with the script condition. For example, the following snippet adds a condition to check if the search returned more than five hits:

{
  "input" : {
    "search" : {
      "request" : {
        "indices" : [ "logs" ],
        "body" : {
          "query" : { "match_all" : {} }
        }
      }
    }
  },
  "condition" : {
    "compare" : { "ctx.payload.hits.total.value" : { "gt" : 5 }}
  }
  ...
}

Accessing the search results

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Conditions, transforms, and actions can access the search results through the watch execution context. For example:

  • To load all of the search hits into an email body, use ctx.payload.hits.
  • To reference the total number of hits, use ctx.payload.hits.total.value.
  • To access a particular hit, use its zero-based array index. For example, to get the third hit, use ctx.payload.hits.hits.2.
  • To get a field value from a particular hit, use ctx.payload.hits.hits.<index>.fields.<fieldname>. For example, to get the message field from the first hit, use ctx.payload.hits.hits.0.fields.message.

The total number of hits in the search response is returned as an object in the response. It contains a value, the number of hits, and a relation that indicates if the value is accurate ("eq") or a lower bound of the total hits that match the query ("gte"). You can set track_total_hits to true in the search request to tell Elasticsearch to always track the number of hits accurately.

Search Input Attributes

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Name Required Default Description

request.search_type

no

query_then_fetch

The type of search request to perform. Valid values are: dfs_query_and_fetch, dfs_query_then_fetch, query_and_fetch, and query_then_fetch. The Elasticsearch default is query_then_fetch.

request.indices

no

-

The indices to search. If omitted, all indices are searched, which is the default behaviour in Elasticsearch.

request.body

no

-

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.template

no

-

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

request.indices_options.expand_wildcards

no

open

How to expand wildcards. Valid values are: all, open, closed, and none See expand_wildcards for more information.

request.indices_options.ignore_unavailable

no

true

Whether the search should ignore unavailable indices. See ignore_unavailable for more information.

request.indices_options.allow_no_indices

no

true

Whether to allow a search where a wildcard indices expression results in no concrete indices. See allow_no_indices for more information.

extract

no

-

A array of JSON keys to extract from the search response and load as the payload. When a search generates a large response, you can use extract to select the relevant fields instead of loading the entire response.

timeout

no

30s

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

You can reference the following variables in the execution context when specifying the request body:

Name Description

ctx.watch_id

The id of the watch that is currently executing.

ctx.execution_time

The time execution of this watch started.

ctx.trigger.triggered_time

The time this watch was triggered.

ctx.trigger.scheduled_time

The time this watch was supposed to be triggered.

ctx.metadata.*

Any metadata associated with the watch.
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