Adds OpenTelemetry source support for metrics pipelines (#3580)

Co-authored-by: ci.datadog-api-spec <packages@datadoghq.com>

Author: api-clients-generation-pipeline[bot]

.generator/schemas/v2/openapi.yaml

@@ -44821,7 +44821,7 @@ components:
         Protocol (OTLP) over gRPC and HTTP.
 
 
-        **Supported pipeline types:** logs'
+        **Supported pipeline types:** logs, metrics'
       properties:
         grpc_address_key:
           description: Environment variable name containing the gRPC server address
@@ -44851,6 +44851,7 @@ components:
       type: object
       x-pipeline-types:
       - logs
+      - metrics
     ObservabilityPipelineOpentelemetrySourceType:
       default: opentelemetry
       description: The source type. The value should always be `opentelemetry`.

cassettes/v2/Observability-Pipelines_4170000189/Validate-a-metrics-pipeline-with-opentelemetry-source-returns-OK-response_2206423067/frozen.json

@@ -0,0 +1 @@
+"2026-03-10T16:11:47.487Z"

cassettes/v2/Observability-Pipelines_4170000189/Validate-a-metrics-pipeline-with-opentelemetry-source-returns-OK-response_2206423067/recording.har

@@ -0,0 +1,67 @@
+{
+  "log": {
+    "_recordingName": "Observability Pipelines/Validate a metrics pipeline with opentelemetry source returns \"OK\" response",
+    "creator": {
+      "comment": "persister:fs",
+      "name": "Polly.JS",
+      "version": "6.0.5"
+    },
+    "entries": [
+      {
+        "_id": "fd62c635471ab911f21d26a9cd87afdc",
+        "_order": 0,
+        "cache": {},
+        "request": {
+          "bodySize": 499,
+          "cookies": [],
+          "headers": [
+            {
+              "_fromType": "array",
+              "name": "accept",
+              "value": "application/json"
+            },
+            {
+              "_fromType": "array",
+              "name": "content-type",
+              "value": "application/json"
+            }
+          ],
+          "headersSize": 582,
+          "httpVersion": "HTTP/1.1",
+          "method": "POST",
+          "postData": {
+            "mimeType": "application/json",
+            "params": [],
+            "text": "{\"data\":{\"attributes\":{\"config\":{\"destinations\":[{\"id\":\"datadog-metrics-destination\",\"inputs\":[\"my-processor-group\"],\"type\":\"datadog_metrics\"}],\"pipeline_type\":\"metrics\",\"processor_groups\":[{\"enabled\":true,\"id\":\"my-processor-group\",\"include\":\"*\",\"inputs\":[\"opentelemetry-source\"],\"processors\":[{\"enabled\":true,\"id\":\"filter-processor\",\"include\":\"env:production\",\"type\":\"filter\"}]}],\"sources\":[{\"id\":\"opentelemetry-source\",\"type\":\"opentelemetry\"}]},\"name\":\"Metrics OTel Pipeline\"},\"type\":\"pipelines\"}}"
+          },
+          "queryString": [],
+          "url": "https://api.datadoghq.com/api/v2/obs-pipelines/pipelines/validate"
+        },
+        "response": {
+          "bodySize": 14,
+          "content": {
+            "mimeType": "application/vnd.api+json",
+            "size": 14,
+            "text": "{\"errors\":[]}\n"
+          },
+          "cookies": [],
+          "headers": [
+            {
+              "name": "content-type",
+              "value": "application/vnd.api+json"
+            }
+          ],
+          "headersSize": 370,
+          "httpVersion": "HTTP/1.1",
+          "redirectURL": "",
+          "status": 200,
+          "statusText": "OK"
+        },
+        "startedDateTime": "2026-03-10T16:11:48.649Z",
+        "time": 211
+      }
+    ],
+    "pages": [],
+    "version": "1.2"
+  }
+}

features/v2/observability_pipelines.feature

@@ -149,6 +149,14 @@ Feature: Observability Pipelines
     And the response "data.attributes.config.destinations" has length 1
     And the response "data.attributes.config.destinations[0].id" is equal to "updated-datadog-logs-destination-id"
 
+  @team:DataDog/observability-pipelines
+  Scenario: Validate a metrics pipeline with opentelemetry source returns "OK" response
+    Given new "ValidatePipeline" request
+    And body with value {"data": {"attributes": {"config": {"pipeline_type": "metrics", "destinations": [{"id": "datadog-metrics-destination", "inputs": ["my-processor-group"], "type": "datadog_metrics"}], "processor_groups": [{"enabled": true, "id": "my-processor-group", "include": "*", "inputs": ["opentelemetry-source"], "processors": [{"enabled": true, "id": "filter-processor", "include": "env:production", "type": "filter"}]}], "sources": [{"id": "opentelemetry-source", "type": "opentelemetry"}]}, "name": "Metrics OTel Pipeline"}, "type": "pipelines"}}
+    When the request is sent
+    Then the response status is 200 OK
+    And the response "errors" has length 0
+
   @team:DataDog/observability-pipelines
   Scenario: Validate an observability pipeline returns "Bad Request" response
     Given new "ValidatePipeline" request

services/observability_pipelines/src/v2/models/ObservabilityPipelineOpentelemetrySource.ts

@@ -6,7 +6,7 @@ import { ObservabilityPipelineTls } from "./ObservabilityPipelineTls";
 /**
  * The `opentelemetry` source receives telemetry data using the OpenTelemetry Protocol (OTLP) over gRPC and HTTP.
  *
- * **Supported pipeline types:** logs
+ * **Supported pipeline types:** logs, metrics
  */
 export class ObservabilityPipelineOpentelemetrySource {
   /**