[[simulate-pipeline-api]]
=== Simulate Pipeline API

The simulate pipeline API executes a specific pipeline against
the set of documents provided in the body of the request.

You can either specify an existing pipeline to execute
against the provided documents, or supply a pipeline definition in
the body of the request.

Here is the structure of a simulate request with a pipeline definition provided
in the body of the request:

[source,js]
--------------------------------------------------
POST _ingest/pipeline/_simulate
{
  "pipeline" : {
    // pipeline definition here
  },
  "docs" : [
    { "_source": {/** first document **/} },
    { "_source": {/** second document **/} },
    // ...
  ]
}
--------------------------------------------------
// NOTCONSOLE

Here is the structure of a simulate request against an existing pipeline:

[source,js]
--------------------------------------------------
POST _ingest/pipeline/my-pipeline-id/_simulate
{
  "docs" : [
    { "_source": {/** first document **/} },
    { "_source": {/** second document **/} },
    // ...
  ]
}
--------------------------------------------------
// NOTCONSOLE

Here is an example of a simulate request with a pipeline defined in the request
and its response:

[source,console]
--------------------------------------------------
POST _ingest/pipeline/_simulate
{
  "pipeline" :
  {
    "description": "_description",
    "processors": [
      {
        "set" : {
          "field" : "field2",
          "value" : "_value"
        }
      }
    ]
  },
  "docs": [
    {
      "_index": "index",
      "_id": "id",
      "_source": {
        "foo": "bar"
      }
    },
    {
      "_index": "index",
      "_id": "id",
      "_source": {
        "foo": "rab"
      }
    }
  ]
}
--------------------------------------------------

Response:

[source,console-result]
--------------------------------------------------
{
   "docs": [
      {
         "doc": {
            "_id": "id",
            "_index": "index",
            "_type": "_doc",
            "_source": {
               "field2": "_value",
               "foo": "bar"
            },
            "_ingest": {
               "timestamp": "2017-05-04T22:30:03.187Z"
            }
         }
      },
      {
         "doc": {
            "_id": "id",
            "_index": "index",
            "_type": "_doc",
            "_source": {
               "field2": "_value",
               "foo": "rab"
            },
            "_ingest": {
               "timestamp": "2017-05-04T22:30:03.188Z"
            }
         }
      }
   ]
}
--------------------------------------------------
// TESTRESPONSE[s/"2017-05-04T22:30:03.187Z"/$body.docs.0.doc._ingest.timestamp/]
// TESTRESPONSE[s/"2017-05-04T22:30:03.188Z"/$body.docs.1.doc._ingest.timestamp/]

[[ingest-verbose-param]]
==== Viewing Verbose Results
You can use the simulate pipeline API to see how each processor affects the ingest document
as it passes through the pipeline. To see the intermediate results of
each processor in the simulate request, you can add the `verbose` parameter
to the request.

Here is an example of a verbose request and its response:

[source,console]
--------------------------------------------------
POST _ingest/pipeline/_simulate?verbose
{
  "pipeline" :
  {
    "description": "_description",
    "processors": [
      {
        "set" : {
          "field" : "field2",
          "value" : "_value2"
        }
      },
      {
        "set" : {
          "field" : "field3",
          "value" : "_value3"
        }
      }
    ]
  },
  "docs": [
    {
      "_index": "index",
      "_id": "id",
      "_source": {
        "foo": "bar"
      }
    },
    {
      "_index": "index",
      "_id": "id",
      "_source": {
        "foo": "rab"
      }
    }
  ]
}
--------------------------------------------------

Response:

[source,console-result]
--------------------------------------------------
{
   "docs": [
      {
         "processor_results": [
            {
               "doc": {
                  "_id": "id",
                  "_index": "index",
                  "_type": "_doc",
                  "_source": {
                     "field2": "_value2",
                     "foo": "bar"
                  },
                  "_ingest": {
                     "timestamp": "2017-05-04T22:46:09.674Z"
                  }
               }
            },
            {
               "doc": {
                  "_id": "id",
                  "_index": "index",
                  "_type": "_doc",
                  "_source": {
                     "field3": "_value3",
                     "field2": "_value2",
                     "foo": "bar"
                  },
                  "_ingest": {
                     "timestamp": "2017-05-04T22:46:09.675Z"
                  }
               }
            }
         ]
      },
      {
         "processor_results": [
            {
               "doc": {
                  "_id": "id",
                  "_index": "index",
                  "_type": "_doc",
                  "_source": {
                     "field2": "_value2",
                     "foo": "rab"
                  },
                  "_ingest": {
                     "timestamp": "2017-05-04T22:46:09.676Z"
                  }
               }
            },
            {
               "doc": {
                  "_id": "id",
                  "_index": "index",
                  "_type": "_doc",
                  "_source": {
                     "field3": "_value3",
                     "field2": "_value2",
                     "foo": "rab"
                  },
                  "_ingest": {
                     "timestamp": "2017-05-04T22:46:09.677Z"
                  }
               }
            }
         ]
      }
   ]
}
--------------------------------------------------
// TESTRESPONSE[s/"2017-05-04T22:46:09.674Z"/$body.docs.0.processor_results.0.doc._ingest.timestamp/]
// TESTRESPONSE[s/"2017-05-04T22:46:09.675Z"/$body.docs.0.processor_results.1.doc._ingest.timestamp/]
// TESTRESPONSE[s/"2017-05-04T22:46:09.676Z"/$body.docs.1.processor_results.0.doc._ingest.timestamp/]
// TESTRESPONSE[s/"2017-05-04T22:46:09.677Z"/$body.docs.1.processor_results.1.doc._ingest.timestamp/]