This pipeline can be used to simulate the execution of a 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. To simulate the ingest pipeline, add the _simulate endpoint to the pipeline API.

The following is an example of simulating an existing pipeline: 

curl -X POST  http://localhost:9200/_ingest/pipeline/firstpipeline/_simulate -H 'content-type: application/json' -d '{
  "docs" : [
    { "_source": {"message":"first document"} },
    { "_source": {"message":"second document"} }
    
  ]
}'

The following is an example of a simulated request, with the pipeline definition in the body of the request itself:

curl -X POST http://localhost:9200/_ingest/pipeline/_simulate -H 'content-type: application/json' -d '{
  "pipeline" : {
    "processors":[
      {
         "join": {
          "field": "message",
          "separator": "-"
        }
      }]
  },
  "docs" : [
    { "_source": {"message":["first","document"]} }
    
  ]
}'