Add metrics traces use case to Data Prepper (#6251)

* Add metrics traces use case to Data Prepper

---------

Signed-off-by: Melissa Vagi <vagimeli@amazon.com>

_data-prepper/common-use-cases/metrics-traces.md

@@ -0,0 +1,51 @@
+---
+layout: default
+title: Deriving metrics from traces
+parent: Common use cases
+nav_order: 60
+---
+
+# Deriving metrics from traces
+
+You can use Data Prepper to derive metrics from OpenTelemetry traces. The following example pipeline receives incoming traces and extracts a metric called `durationInNanos`, aggregated over a tumbling window of 30 seconds. It then derives a histogram from the incoming traces.
+
+The pipeline contains the following pipelines:
+
+- `entry-pipeline` – Receives trace data from the OpenTelemetry collector and forwards it to the `trace_to_metrics_pipeline` pipeline.
+
+- `trace-to-metrics-pipeline` - Receives the trace data from the `entry-pipeline` pipeline, aggregates it, and derives a histogram of `durationInNanos` from the traces based on the value of the `serviceName` field. It then sends the derived metrics to the OpenSearch index called `metrics_for_traces`.
+
+```json
+entry-pipeline:
+  source:
+    otel_trace_source:
+      # Provide the path for ingestion. ${pipelineName} will be replaced with pipeline name.
+      # In this case it would be "/entry-pipeline/v1/traces". This will be endpoint URI path in OpenTelemetry Exporter configuration.
+      path: "/${pipelineName}/v1/traces"
+  sink:
+    - pipeline:
+        name: "trace-to-metrics-pipeline"
+
+trace-to-metrics-pipeline:
+  source:
+    pipeline:
+      name: "entry-pipeline"
+  processor:
+    - aggregate:
+        # Pick the required identification keys
+        identification_keys: ["serviceName"]
+        action:
+          histogram:
+            # Pick the appropriate values for each of the following fields
+            key: "durationInNanos"
+            record_minmax: true
+            units: "seconds"
+            buckets: [0, 10000000, 50000000, 100000000]
+        # Specify an aggregation period
+        group_duration: "30s"
+  sink:
+    - opensearch:
+        ...
+        index: "metrics_for_traces"
+```
+{% include copy-curl.html %}