PUT _ingest/pipeline/my-final-pipeline
{
  "description": "create event.source",
  "processors": [
    {
      "set": {
        "field": "user.name",
        "value": "my-user-name",
        "ignore_failure": false
      }
    }
  ]
}

# Create an index which the final_pipeline is my-final-pipeline
# PUT /<my-index-{now/d}>
PUT /%3Cmy-index-%7Bnow%2Fd%7D%3E
{
  "settings": {
    "index.final_pipeline": "my-final-pipeline"
  }
}

# Index a document using the date math expression in the URL:
POST %3Cmy-index-%7Bnow%2Fd%7D%3E/_doc/1
{
  "foo": "bar"
}

# observe that user.name field is not set by the final pipeline