Add Trace peer forwarder doc.

_data-prepper/pipelines/configuration/processors/trace-peer-forwarder.md

@@ -0,0 +1,54 @@
+---
+layout: default
+title: Trace peer forwarder
+parent: Processors
+grand_parent: Pipelines
+nav_order: 45
+---
+
+# Trace peer forwarder
+
+The `Trace peer forwarder` processor is used to reduce the number of events that are forwarded in a [Trace analytics]({{site.url}}{{site.baseurl}}/data-prepper/common-use-cases/trace-analytics/) pipeline by half when using [Peer forwarder]({{site.url}}{{site.baseurl}}/data-prepper/managing-data-prepper/peer-forwarder/). Pipelines peer forward events, which causes the core peer forwarder to make multiple HTTP requests for the same event. You can use `Trace peer forwarder` to forward the event one time in the entry pipeline (`otel-trace`) instead of other pipelines, such as `service-map-pipeline` and `raw-pipeline`, and prevents unnecessary HTTP requests. `Trace peer forwarder` groups events based on `trace_id` similar to the `service_map_stateful` and `otel_trace_raw ` processors. 
+
+You should use `Trace peer forwarder` when you have multiple nodes, and for trace analytics pipelines.
+
+In [Trace analytics]({{site.url}}{{site.baseurl}}/data-prepper/common-use-cases/trace-analytics/), each event is duplicated when it is sent from the `otel-trace-pipeline` to the `raw-pipeline` and to the `service-map-pipeline`. The event is forwarded once in each pipeline. When you use this processor, the event is forwarded once in the `otel-trace-pipeline` pipeline to the correct peer. 
+
+## Usage
+
+To get started with `Trace peer forwarder`, configure [Peer forwarder]({{site.url}}{{site.baseurl}}/managing-data-prepper/peer-forwarder/). Then, create the a `pipeline.yaml` file and include `Trace peer forwarder` in your `pipeline.yaml` file. You can configure `Peer forwarder` in your `data-prepper-config.yaml` file. For more detailed information, see [Configuring Data Prepper]({{site.url}}{{site.baseurl}}/data-prepper/getting-started/#2-configuring-data-prepper).
+
+See the following `pipeline.yaml` file example: 
+
+```yaml
+otel-trace-pipeline:
+  delay: "100"
+  source:
+    otel_trace_source:
+  processor:
+    - trace_peer_forwarder:
+  sink:
+    - pipeline:
+        name: "raw-pipeline"
+    - pipeline:
+        name: "service-map-pipeline"
+raw-pipeline:
+  source:
+    pipeline:
+      name: "entry-pipeline"
+  processor:
+    - otel_trace_raw:
+  sink:
+    - opensearch:
+service-map-pipeline:
+  delay: "100"
+  source:
+    pipeline:
+      name: "entry-pipeline"
+  processor:
+    - service_map_stateful:
+  sink:
+    - opensearch:
+```
+
+In the preceding `pipeline.yaml` file, events are forwarded in the `otel-trace-pipeline` to the target peer, and no forwarding is performed in `raw-pipeline` or `service-map-pipeline`. This process helps improve network performance by forwarding events (as HTTP requests) once instead of twice.