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Simulate index template API

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Simulate index template API

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This functionality is in technical preview and may be changed or removed in a future release. Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of official GA features.

Returns the index configuration that would be applied by a particular index template.

POST /_index_template/_simulate/template_1

Request

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POST /_index_template/_simulate/<index-template>

Prerequisites

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If the Elasticsearch security features are enabled, you must have the manage_index_templates or manage cluster privilege to use this API.

Path parameters

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<index-template>: (Optional, string) Name of the index template to simulate. To test a template configuration before you add it to the cluster, omit this parameter and specify the template configuration in the request body.

Query parameters

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create: (Optional, Boolean) If true, the template passed in the body is only used if no existing templates match the same index patterns. If false, the simulation uses the template with the highest priority. Note that the template is not permanently added or updated in either case; it is only used for the simulation. Defaults to false.
master_timeout: (Optional, time units) Period to wait for a connection to the master node. If no response is received before the timeout expires, the request fails and returns an error. Defaults to 30s.

Request body

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composed_of

(Optional, array of strings) Ordered list of component template names. Component templates are merged in the order specified, meaning that the last component template specified has the highest precedence. For an example, see Composing multiple component templates.

index_patterns

(Required, array of strings) Array of wildcard (*) expressions used to match the names of indices during creation.

priority

(Optional, integer) Priority that determines what template is applied if there are multiple templates that match the name of a new index. The highest priority template takes precedence. Defaults to 0 (lowest priority).

template

(Optional, object) Template to apply.

Properties of template

aliases

(Optional, alias object) Index aliases which include the index. See Update index alias.

mappings

(Optional, mapping object) Mapping for fields in the index. If specified, this mapping can include:

See Mapping.

settings

(Optional, index setting object) Configuration options for the index. See Index Settings.

version

(Optional, integer) Version number used to manage index templates externally. This version is not automatically generated by Elasticsearch.

_meta

(Optional, object) User-specified metadata for the index template. This information is not generated or used by Elasticsearch.

Response body

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overlapping

(array) Any templates that were superseded by the specified template.

Properties of overlapping

index_patterns: (array) Index patterns that the superseded template applies to.
name: (string) Name of the superseded template.

template

(object) The settings, mappings, and aliases that would be applied to matching indices.

Properties of template

aliases

(Optional, alias object) Index aliases which include the index. See Update index alias.

mappings

(Optional, mapping object) Mapping for fields in the index. If specified, this mapping can include:

See Mapping.

settings

(Optional, index setting object) Configuration options for the index. See Index Settings.

Examples

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Simulating an existing template

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The following example creates and simulates a composed template:

PUT /_component_template/ct1                   
{
  "template": {
    "settings": {
      "index.number_of_shards": 2
    }
  }
}

PUT /_component_template/ct2                    
{
  "template": {
    "settings": {
      "index.number_of_replicas": 0
    },
    "mappings": {
      "properties": {
        "@timestamp": {
          "type": "date"
        }
      }
    }
  }
}

PUT /_index_template/final-template            
{
  "index_patterns": ["my-index-*"],
  "composed_of": ["ct1", "ct2"],
  "priority": 5
}

POST /_index_template/_simulate/final-template

	Create a component template (`ct1`) that sets the number of shards to 2
	Create a component template (`ct2`) that sets the number of replicas to 0 and defines a mapping
	Create an index template (`final-template`) that uses the component templates
	Show the configuration applied by the `final-template`

The response shows the index settings, mappings, and aliases applied by the final-template:

{
  "template" : {
    "settings" : {
      "index" : {
        "number_of_shards" : "2",  
        "number_of_replicas" : "0" 
      }
    },
    "mappings" : {                 
      "properties" : {
        "@timestamp" : {
          "type" : "date"
        }
      }
    },
    "aliases" : { }
  },
  "overlapping" : [ ]
}

	Number of shards from `ct1`
	Number of replicas from `ct2`
	Mappings from `ct1`

Simulating an arbitrary template configuration

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To see what settings will be applied by a template before you add it to the cluster, you can pass a template configuration in the request body. The specified template is used for the simulation if it has a higher priority than existing templates.

POST /_index_template/_simulate
{
  "index_patterns": ["my-index-*"],
  "composed_of": ["ct2"],
  "priority": 10,
  "template": {
    "settings": {
      "index.number_of_replicas": 1
    }
  }
}

The response shows any overlapping templates with a lower priority.

{
  "template" : {
    "settings" : {
      "index" : {
        "number_of_replicas" : "1"
      }
    },
    "mappings" : {
      "properties" : {
        "@timestamp" : {
          "type" : "date"
        }
      }
    },
    "aliases" : { }
  },
  "overlapping" : [
    {
      "name" : "final-template",
      "index_patterns" : [
        "my-index-*"
      ]
    }
  ]
}

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