Add rename ingest processor

_ingest-pipelines/processors/index-processors.md

@@ -54,6 +54,7 @@ Processor type | Description
 `pipeline` | Runs an inner pipeline.
 `remove` | Removes fields from a document.
 `remove_by_pattern` | Removes fields from a document by field pattern.
+`rename` | Renames an existing field.
 `script` | Runs an inline or stored script on incoming documents. 
 `set` | Sets the value of a field to a specified value.
 `sort` | Sorts the elements of an array in ascending or descending order.

_ingest-pipelines/processors/rename.md

@@ -0,0 +1,141 @@
+---
+layout: default
+title: Rename
+parent: Ingest processors
+nav_order: 230
+redirect_from:
+   - /api-reference/ingest-apis/processors/rename/
+---
+
+# Rename processor
+
+The `rename` processor is used to rename an existing field, which can also be used to move a field from one object to another object or the root level.
+
+## Syntax
+
+The following is the syntax for the `rename` processor: 
+
+```json
+{
+    "rename": {
+        "field": "field_name",
+        "target_field" : "target_field_name"
+    }
+}
+```
+{% include copy-curl.html %}
+
+## Configuration parameters
+
+The following table lists the required and optional parameters for the `rename` processor.
+
+| Parameter  | Required/Optional  | Description  |
+|---|---|---|
+`field`  | Required  | The field name containing the data to be removed. Supports [template snippets]({{site.url}}{{site.baseurl}}/ingest-pipelines/create-ingest/#template-snippets). |
+`target_field`  | Required  | The new name of the field. Supports [template snippets]({{site.url}}{{site.baseurl}}/ingest-pipelines/create-ingest/#template-snippets). |
+`ignore_missing`  | Optional  | Specifies whether the processor should ignore documents that do not contain the specified `field`. If set to `true`, the processor does not modify the document if the `field` does not exist. Default is `false`. |
+`description`  | Optional  | A brief description of the processor.  |
+`if` | Optional | A condition for running the processor. |
+`ignore_failure` | Optional | Specifies whether the processor continues execution even if it encounters errors. If set to `true`, failures are ignored. Default is `false`. |
+`on_failure` | Optional | A list of processors to run if the processor fails. |
+`tag` | Optional | An identifier tag for the processor. Useful for debugging in order to distinguish between processors of the same type. |
+
+## Using the processor
+
+Follow these steps to use the processor in a pipeline.
+
+**Step 1: Create a pipeline** 
+
+The following query creates a pipeline named `rename_field` that moves a field in a object to the root level: 
+
+```json
+PUT /_ingest/pipeline/rename_field
+{
+  "description": "Pipeline that moves a field to the root level.",
+  "processors": [
+    {
+      "rename": {
+        "field": "message.content",
+        "target_field": "content"
+      }
+    }
+  ]
+}
+```
+{% include copy-curl.html %}
+
+**Step 2 (Optional): Test the pipeline**
+
+It is recommended that you test your pipeline before ingesting documents.
+{: .tip}
+
+To test the pipeline, run the following query:
+
+```json
+POST _ingest/pipeline/rename_field/_simulate
+{
+  "docs": [
+    {
+      "_index": "testindex1",
+      "_id": "1",
+      "_source":{
+         "message": {
+           "type": "nginx",
+           "content": "192.168.1.10 - - [03/Nov/2023:15:20:45 +0000] \"POST /login HTTP/1.1\" 200 3456"
+         }
+      }
+    }
+  ]
+}
+```
+{% include copy-curl.html %}
+
+**Response**
+
+The following example response confirms that the pipeline is working as expected:
+
+```json
+{
+  "docs": [
+    {
+      "doc": {
+        "_index": "testindex1",
+        "_id": "1",
+        "_source": {
+          "message": {
+            "type": "nginx",
+          },
+          "content": """192.168.1.10 - - [03/Nov/2023:15:20:45 +0000] "POST /login HTTP/1.1" 200 3456"""
+        },
+        "_ingest": {
+          "timestamp": "2024-04-15T07:54:16.010447Z"
+        }
+      }
+    }
+  ]
+}
+```
+
+**Step 3: Ingest a document**
+
+The following query ingests a document into an index named `testindex1`:
+
+```json
+PUT testindex1/_doc/1?pipeline=rename_field
+{
+  "message": {
+    "type": "nginx",
+    "content": "192.168.1.10 - - [03/Nov/2023:15:20:45 +0000] \"POST /login HTTP/1.1\" 200 3456"
+  }
+}
+```
+{% include copy-curl.html %}
+
+**Step 4 (Optional): Retrieve the document**
+
+To retrieve the document, run the following query:
+
+```json
+GET testindex1/_doc/1
+```
+{% include copy-curl.html %}