[SIEM][Detection Engine] Adds an error aggregator by error reason and…

… a way to filter them

## Summary

Changes the error handling for when responses are returning with errors from the backend. We were aggregating on error status codes, but this will aggregate on the error reason per rule run and report those instead.

* Adds a utility function
* Adds unit tests for the utility function
* Adds TypeScript Types for the utility function
* Adds sample helpers for the mocks for testing 

### Checklist

- [x] [Unit or functional tests](https://github.com/elastic/kibana/blob/master/CONTRIBUTING.md#cross-browser-compatibility) were updated or added to match the most common scenarios

x-pack/legacy/plugins/siem/server/lib/detection_engine/signals/__mocks__/es_results.ts

@@ -4,7 +4,7 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-import { SignalSourceHit, SignalSearchResponse } from '../types';
+import { SignalSourceHit, SignalSearchResponse, BulkResponse, BulkItem } from '../types';
 import {
   Logger,
   SavedObject,
@@ -416,3 +416,68 @@ export const exampleFindRuleStatusResponse: (
 });
 
 export const mockLogger: Logger = loggingServiceMock.createLogger();
+
+export const sampleBulkErrorItem = (
+  {
+    status,
+    reason,
+  }: {
+    status: number;
+    reason: string;
+  } = { status: 400, reason: 'Invalid call' }
+): BulkItem => {
+  return {
+    create: {
+      _index: 'mock_index',
+      _id: '123',
+      _version: 1,
+      status,
+      _shards: {
+        total: 1,
+        successful: 0,
+        failed: 1,
+      },
+      error: {
+        type: 'Invalid',
+        reason,
+        shard: 'shard 123',
+        index: 'mock_index',
+      },
+    },
+  };
+};
+
+export const sampleBulkItem = (): BulkItem => {
+  return {
+    create: {
+      _index: 'mock_index',
+      _id: '123',
+      _version: 1,
+      status: 200,
+      result: 'some result here',
+      _shards: {
+        total: 1,
+        successful: 1,
+        failed: 0,
+      },
+    },
+  };
+};
+
+export const sampleEmptyBulkResponse = (): BulkResponse => ({
+  took: 0,
+  errors: false,
+  items: [],
+});
+
+export const sampleBulkError = (): BulkResponse => ({
+  took: 0,
+  errors: true,
+  items: [sampleBulkErrorItem()],
+});
+
+export const sampleBulkResponse = (): BulkResponse => ({
+  took: 0,
+  errors: true,
+  items: [sampleBulkItem()],
+});

x-pack/legacy/plugins/siem/server/lib/detection_engine/signals/single_bulk_create.ts

@@ -10,7 +10,7 @@ import { AlertServices } from '../../../../../../../plugins/alerting/server';
 import { SignalSearchResponse, BulkResponse } from './types';
 import { RuleAlertAction } from '../../../../common/detection_engine/types';
 import { RuleTypeParams, RefreshTypes } from '../types';
-import { generateId, makeFloatString } from './utils';
+import { generateId, makeFloatString, errorAggregator } from './utils';
 import { buildBulkBody } from './build_bulk_body';
 import { Logger } from '../../../../../../../../src/core/server';
 
@@ -134,17 +134,10 @@ export const singleBulkCreate = async ({
   logger.debug(`took property says bulk took: ${response.took} milliseconds`);
 
   if (response.errors) {
-    const itemsWithErrors = response.items.filter(item => item.create.error);
-    const errorCountsByStatus = countBy(itemsWithErrors, item => item.create.status);
-    delete errorCountsByStatus['409']; // Duplicate signals are expected
-
-    if (!isEmpty(errorCountsByStatus)) {
+    const errorCountByMessage = errorAggregator(response, [409]);
+    if (!isEmpty(errorCountByMessage)) {
       logger.error(
-        `[-] bulkResponse had errors with response statuses:counts of...\n${JSON.stringify(
-          errorCountsByStatus,
-          null,
-          2
-        )}`
+        `[-] bulkResponse had errors with responses of: ${JSON.stringify(errorCountByMessage)}`
       );
     }
   }

x-pack/legacy/plugins/siem/server/lib/detection_engine/signals/types.ts

@@ -59,35 +59,35 @@ export interface SignalSource {
   };
 }
 
+export interface BulkItem {
+  create: {
+    _index: string;
+    _type?: string;
+    _id: string;
+    _version: number;
+    result?: string;
+    _shards?: {
+      total: number;
+      successful: number;
+      failed: number;
+    };
+    _seq_no?: number;
+    _primary_term?: number;
+    status: number;
+    error?: {
+      type: string;
+      reason: string;
+      index_uuid?: string;
+      shard: string;
+      index: string;
+    };
+  };
+}
+
 export interface BulkResponse {
   took: number;
   errors: boolean;
-  items: [
-    {
-      create: {
-        _index: string;
-        _type?: string;
-        _id: string;
-        _version: number;
-        result?: string;
-        _shards?: {
-          total: number;
-          successful: number;
-          failed: number;
-        };
-        _seq_no?: number;
-        _primary_term?: number;
-        status: number;
-        error?: {
-          type: string;
-          reason: string;
-          index_uuid?: string;
-          shard: string;
-          index: string;
-        };
-      };
-    }
-  ];
+  items: BulkItem[];
 }
 
 export interface MGetResponse {
@@ -169,3 +169,5 @@ export interface RuleAlertAttributes extends AlertAttributes {
     ruleId: string;
   };
 }
+
+export type BulkResponseErrorAggregation = Record<string, { count: number; statusCode: number }>;