[APM] Add telemetry for top traces (#166263)

Closes #161985

x-pack/plugins/apm/server/lib/apm_telemetry/collect_data_telemetry/tasks.test.ts

@@ -590,4 +590,56 @@ describe('data telemetry collection tasks', () => {
       });
     });
   });
+
+  describe('top_traces', () => {
+    const task = tasks.find((t) => t.name === 'top_traces');
+
+    it('returns max and median number of documents in top traces', async () => {
+      const search = jest.fn().mockResolvedValueOnce({
+        aggregations: {
+          top_traces: {
+            buckets: [
+              {
+                key: '521485',
+                doc_count: 1026,
+              },
+              {
+                key: '594439',
+                doc_count: 1025,
+              },
+              {
+                key: '070251',
+                doc_count: 1023,
+              },
+              {
+                key: '108079',
+                doc_count: 1023,
+              },
+              {
+                key: '118887',
+                doc_count: 1023,
+              },
+            ],
+          },
+          max: {
+            value: 1026,
+          },
+          median: {
+            values: {
+              '50.0': 1023,
+            },
+          },
+        },
+      });
+
+      expect(
+        await task?.executor({ indices, telemetryClient: { search } } as any)
+      ).toEqual({
+        top_traces: {
+          max: 1026,
+          median: 1023,
+        },
+      });
+    });
+  });
 });

x-pack/plugins/apm/server/lib/apm_telemetry/collect_data_telemetry/tasks.ts

@@ -39,6 +39,7 @@ import {
   SERVICE_RUNTIME_NAME,
   SERVICE_RUNTIME_VERSION,
   SERVICE_VERSION,
+  TRACE_ID,
   TRANSACTION_NAME,
   TRANSACTION_RESULT,
   TRANSACTION_TYPE,
@@ -1484,4 +1485,48 @@ export const tasks: TelemetryTask[] = [
       };
     },
   },
+  {
+    name: 'top_traces',
+    executor: async ({ indices, telemetryClient }) => {
+      const response = await telemetryClient.search({
+        index: [indices.transaction, indices.span, indices.error],
+        body: {
+          size: 0,
+          track_total_hits: false,
+          timeout,
+          query: {
+            bool: {
+              filter: [range1d],
+            },
+          },
+          aggs: {
+            top_traces: {
+              terms: {
+                field: TRACE_ID,
+                size: 100,
+              },
+            },
+            max: {
+              max_bucket: {
+                buckets_path: 'top_traces>_count',
+              },
+            },
+            median: {
+              percentiles_bucket: {
+                buckets_path: 'top_traces>_count',
+                percents: [50],
+              },
+            },
+          },
+        },
+      });
+
+      return {
+        top_traces: {
+          max: response.aggregations?.max.value ?? 0,
+          median: response.aggregations?.median.values['50.0'] ?? 0,
+        },
+      };
+    },
+  },
 ];

x-pack/plugins/apm/server/lib/apm_telemetry/schema.ts

@@ -1006,6 +1006,22 @@ export const apmSchema: MakeSchemaFrom<APMUsage, true> = {
     },
   },
   per_service: { type: 'array', items: { ...apmPerServiceSchema } },
+  top_traces: {
+    max: {
+      type: 'long',
+      _meta: {
+        description:
+          'Max number of documents in top 100 traces withing the last day',
+      },
+    },
+    median: {
+      type: 'long',
+      _meta: {
+        description:
+          'Median number of documents in top 100 traces within the last day',
+      },
+    },
+  },
   tasks: {
     aggregated_transactions: {
       took: {
@@ -1169,5 +1185,16 @@ export const apmSchema: MakeSchemaFrom<APMUsage, true> = {
         },
       },
     },
+    top_traces: {
+      took: {
+        ms: {
+          type: 'long',
+          _meta: {
+            description:
+              'Execution time in milliseconds for the "top_traces" task',
+          },
+        },
+      },
+    },
   },
 };

x-pack/plugins/apm/server/lib/apm_telemetry/types.ts

@@ -211,6 +211,10 @@ export interface APMUsage {
     total: number;
   };
   per_service: APMPerService[];
+  top_traces: {
+    max: number;
+    median: number;
+  };
   tasks: Record<
     | 'aggregated_transactions'
     | 'cloud'
@@ -226,7 +230,8 @@ export interface APMUsage {
     | 'cardinality'
     | 'environments'
     | 'service_groups'
-    | 'per_service',
+    | 'per_service'
+    | 'top_traces',
     { took: { ms: number } }
   >;
 }

x-pack/plugins/telemetry_collection_xpack/schema/xpack_plugins.json

@@ -5067,6 +5067,22 @@
             }
           }
         },
+        "top_traces": {
+          "properties": {
+            "max": {
+              "type": "long",
+              "_meta": {
+                "description": "Max number of documents in top 100 traces withing the last day"
+              }
+            },
+            "median": {
+              "type": "long",
+              "_meta": {
+                "description": "Median number of documents in top 100 traces within the last day"
+              }
+            }
+          }
+        },
         "tasks": {
           "properties": {
             "aggregated_transactions": {
@@ -5278,6 +5294,20 @@
                   }
                 }
               }
+            },
+            "top_traces": {
+              "properties": {
+                "took": {
+                  "properties": {
+                    "ms": {
+                      "type": "long",
+                      "_meta": {
+                        "description": "Execution time in milliseconds for the \"top_traces\" task"
+                      }
+                    }
+                  }
+                }
+              }
             }
           }
         }