[Reporting] Support 'auto' value for csv scroll duration config (elas…

…tic#175005)

## Summary

Closes elastic#174988


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### Risk Matrix

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Before closing this PR, invite QA, stakeholders, and other developers to
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and how they may potentially impact the change:

| Risk | Probability | Severity | Mitigation/Notes |

|---------------------------|-------------|----------|-------------------------|
| Multiple Spaces&mdash;unexpected behavior in non-default Kibana Space.
| Low | High | Integration tests will verify that all features are still
supported in non-default Kibana Space and when user switches between
spaces. |
| Multiple nodes&mdash;Elasticsearch polling might have race conditions
when multiple Kibana nodes are polling for the same tasks. | High | Low
| Tasks are idempotent, so executing them multiple times will not result
in logical error, but will degrade performance. To test for this case we
add plenty of unit tests around this logic and document manual testing
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| Code should gracefully handle cases when feature X or plugin Y are
disabled. | Medium | High | Unit tests will verify that any feature flag
or plugin combination still results in our service operational. |
| [See more potential risk
examples](https://github.com/elastic/kibana/blob/main/RISK_MATRIX.mdx) |


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docs/settings/reporting-settings.asciidoc

@@ -232,10 +232,10 @@ You may need to lower this setting if the default number of documents creates a
 ============
 
 `xpack.reporting.csv.scroll.duration`::
-Amount of {time-units}[time] allowed before {kib} cleans the scroll context during a CSV export. Defaults to `30s`.
+Amount of {time-units}[time] allowed before {kib} cleans the scroll context during a CSV export. Valid option is either `auto` or {time-units}[time], Defaults to `30s`.
 [NOTE]
 ============
-If search latency in {es} is sufficiently high, such as if you are using {ccs}, you may need to increase the setting.
+If search latency in {es} is sufficiently high, such as if you are using {ccs}, you may either need to increase the time setting or set this config value to `auto`. When the config value is set to `auto` the scroll context will be preserved for as long as is possible, before the report task is terminated due to the limits of `xpack.reporting.queue.timeout`.
 ============
 
 `xpack.reporting.csv.scroll.strategy`::

packages/kbn-generate-csv/src/generate_csv.test.ts

@@ -9,6 +9,7 @@
 import { identity, range } from 'lodash';
 import * as Rx from 'rxjs';
 import type { Writable } from 'stream';
+import { add, type Duration } from 'date-fns';
 
 import { errors as esErrors, estypes } from '@elastic/elasticsearch';
 import type { SearchResponse } from '@elastic/elasticsearch/lib/api/types';
@@ -21,6 +22,8 @@ import {
 } from '@kbn/core/server/mocks';
 import { ISearchClient, ISearchStartSearchSource } from '@kbn/data-plugin/common';
 import { searchSourceInstanceMock } from '@kbn/data-plugin/common/search/search_source/mocks';
+import type { IScopedSearchClient } from '@kbn/data-plugin/server';
+import type { IKibanaSearchResponse } from '@kbn/data-plugin/common';
 import { dataPluginMock } from '@kbn/data-plugin/server/mocks';
 import { FieldFormatsRegistry } from '@kbn/field-formats-plugin/common';
 import { CancellationToken } from '@kbn/reporting-common';
@@ -360,7 +363,11 @@ describe('CsvGenerator', () => {
       expect(mockDataClient.search).toHaveBeenCalledTimes(10);
       expect(mockDataClient.search).toBeCalledWith(
         { params: { body: {}, ignore_throttled: undefined, max_concurrent_shard_requests: 5 } },
-        { strategy: 'es', transport: { maxRetries: 0, requestTimeout: '30s' } }
+        {
+          abortSignal: expect.any(AbortSignal),
+          strategy: 'es',
+          transport: { maxRetries: 0, requestTimeout: '30s' },
+        }
       );
 
       expect(mockEsClient.asCurrentUser.openPointInTime).toHaveBeenCalledTimes(1);
@@ -370,7 +377,12 @@ describe('CsvGenerator', () => {
           index: 'logstash-*',
           keep_alive: '30s',
         },
-        { maxConcurrentShardRequests: 5, maxRetries: 0, requestTimeout: '30s' }
+        {
+          maxConcurrentShardRequests: 5,
+          maxRetries: 0,
+          requestTimeout: '30s',
+          signal: expect.any(AbortSignal),
+        }
       );
 
       expect(mockEsClient.asCurrentUser.closePointInTime).toHaveBeenCalledTimes(1);
@@ -548,6 +560,203 @@ describe('CsvGenerator', () => {
     });
   });
 
+  describe('export behavior when scroll duration config is auto', () => {
+    const getTaskInstanceFields = (intervalFromNow: Duration) => {
+      const now = new Date(Date.now());
+      return { startedAt: now, retryAt: add(now, intervalFromNow) };
+    };
+
+    let mockConfigWithAutoScrollDuration: ReportingConfigType['csv'];
+    let mockDataClientSearchFn: jest.MockedFunction<IScopedSearchClient['search']>;
+
+    beforeEach(() => {
+      mockConfigWithAutoScrollDuration = {
+        ...mockConfig,
+        scroll: {
+          ...mockConfig.scroll,
+          duration: 'auto',
+        },
+      };
+
+      mockDataClientSearchFn = jest.fn();
+
+      jest.useFakeTimers();
+    });
+
+    afterEach(() => {
+      jest.clearAllTimers();
+      jest.useRealTimers();
+
+      mockDataClientSearchFn.mockRestore();
+    });
+
+    it('csv gets generated if search resolves without errors before the computed timeout value passed to the search data client elapses', async () => {
+      const timeFromNowInMs = 4 * 60 * 1000;
+
+      const taskInstanceFields = getTaskInstanceFields({
+        seconds: timeFromNowInMs / 1000,
+      });
+
+      mockDataClientSearchFn.mockImplementation((_, options) => {
+        const getSearchResult = () => {
+          const queuedAt = Date.now();
+
+          return new Promise<IKibanaSearchResponse<ReturnType<typeof getMockRawResponse>>>(
+            (resolve, reject) => {
+              setTimeout(() => {
+                if (
+                  new Date(Date.now()).getTime() - new Date(queuedAt).getTime() >
+                  Number((options?.transport?.requestTimeout! as string).replace(/ms/, ''))
+                ) {
+                  reject(
+                    new esErrors.ResponseError({ statusCode: 408, meta: {} as any, warnings: [] })
+                  );
+                } else {
+                  resolve({
+                    rawResponse: getMockRawResponse(
+                      [
+                        {
+                          fields: { a: ['a1'], b: ['b1'] },
+                        } as unknown as estypes.SearchHit,
+                      ],
+                      3
+                    ),
+                  });
+                }
+              }, timeFromNowInMs / 4);
+            }
+          );
+        };
+
+        return Rx.defer(getSearchResult);
+      });
+
+      const generateCsvPromise = new CsvGenerator(
+        createMockJob({ searchSource: {}, columns: ['a', 'b'] }),
+        mockConfigWithAutoScrollDuration,
+        taskInstanceFields,
+        {
+          es: mockEsClient,
+          data: {
+            ...mockDataClient,
+            search: mockDataClientSearchFn,
+          },
+          uiSettings: uiSettingsClient,
+        },
+        {
+          searchSourceStart: mockSearchSourceService,
+          fieldFormatsRegistry: mockFieldFormatsRegistry,
+        },
+        new CancellationToken(),
+        mockLogger,
+        stream
+      ).generateData();
+
+      await jest.advanceTimersByTimeAsync(timeFromNowInMs);
+
+      expect(await generateCsvPromise).toEqual(
+        expect.objectContaining({
+          warnings: [],
+        })
+      );
+
+      expect(mockDataClientSearchFn).toBeCalledWith(
+        { params: { body: {}, ignore_throttled: undefined, max_concurrent_shard_requests: 5 } },
+        {
+          abortSignal: expect.any(AbortSignal),
+          strategy: 'es',
+          transport: { maxRetries: 0, requestTimeout: `${timeFromNowInMs}ms` },
+        }
+      );
+
+      expect(content).toMatchSnapshot();
+    });
+
+    it('csv generation errors if search request does not resolve before the computed timeout value passed to the search data client elapses', async () => {
+      const timeFromNowInMs = 4 * 60 * 1000;
+
+      const taskInstanceFields = getTaskInstanceFields({
+        seconds: timeFromNowInMs / 1000,
+      });
+
+      const requestDuration = timeFromNowInMs + 1000;
+
+      mockDataClientSearchFn.mockImplementation((_, options) => {
+        const getSearchResult = () => {
+          const queuedAt = Date.now();
+
+          return new Promise<IKibanaSearchResponse<ReturnType<typeof getMockRawResponse>>>(
+            (resolve, reject) => {
+              setTimeout(() => {
+                if (
+                  new Date(Date.now()).getTime() - new Date(queuedAt).getTime() >
+                  Number((options?.transport?.requestTimeout! as string).replace(/ms/, ''))
+                ) {
+                  reject(
+                    new esErrors.ResponseError({ statusCode: 408, meta: {} as any, warnings: [] })
+                  );
+                } else {
+                  resolve({
+                    rawResponse: getMockRawResponse(
+                      [
+                        {
+                          fields: { a: ['a1'], b: ['b1'] },
+                        } as unknown as estypes.SearchHit,
+                      ],
+                      3
+                    ),
+                  });
+                }
+              }, requestDuration);
+            }
+          );
+        };
+
+        return Rx.defer(getSearchResult);
+      });
+
+      const generateCsvPromise = new CsvGenerator(
+        createMockJob({ searchSource: {}, columns: ['a', 'b'] }),
+        mockConfigWithAutoScrollDuration,
+        taskInstanceFields,
+        {
+          es: mockEsClient,
+          data: {
+            ...mockDataClient,
+            search: mockDataClientSearchFn,
+          },
+          uiSettings: uiSettingsClient,
+        },
+        {
+          searchSourceStart: mockSearchSourceService,
+          fieldFormatsRegistry: mockFieldFormatsRegistry,
+        },
+        new CancellationToken(),
+        mockLogger,
+        stream
+      ).generateData();
+
+      await jest.advanceTimersByTimeAsync(requestDuration);
+
+      expect(await generateCsvPromise).toEqual(
+        expect.objectContaining({
+          warnings: expect.arrayContaining([
+            expect.stringContaining('Received a 408 response from Elasticsearch'),
+          ]),
+        })
+      );
+
+      expect(mockDataClientSearchFn).toBeCalledWith(
+        { params: { body: {}, ignore_throttled: undefined, max_concurrent_shard_requests: 5 } },
+        {
+          abortSignal: expect.any(AbortSignal),
+          strategy: 'es',
+          transport: { maxRetries: 0, requestTimeout: `${timeFromNowInMs}ms` },
+        }
+      );
+    });
+  });
+
   describe('Scroll strategy', () => {
     const mockJobUsingScrollPaging = createMockJob({
       columns: ['date', 'ip', 'message'],
@@ -654,7 +863,11 @@ describe('CsvGenerator', () => {
             max_concurrent_shard_requests: 5,
           }),
         },
-        { strategy: 'es', transport: { maxRetries: 0, requestTimeout: '30s' } }
+        {
+          abortSignal: expect.any(AbortSignal),
+          strategy: 'es',
+          transport: { maxRetries: 0, requestTimeout: '30s' },
+        }
       );
 
       expect(mockEsClient.asCurrentUser.openPointInTime).not.toHaveBeenCalled();
@@ -1200,17 +1413,12 @@ describe('CsvGenerator', () => {
         index: 'logstash-*',
         keep_alive: '30s',
       },
-      { maxConcurrentShardRequests: 5, maxRetries: 0, requestTimeout: '30s' }
-    );
-
-    expect(mockEsClient.asCurrentUser.openPointInTime).toHaveBeenCalledWith(
       {
-        ignore_unavailable: true,
-        ignore_throttled: false,
-        index: 'logstash-*',
-        keep_alive: '30s',
-      },
-      { maxConcurrentShardRequests: 5, maxRetries: 0, requestTimeout: '30s' }
+        maxConcurrentShardRequests: 5,
+        maxRetries: 0,
+        requestTimeout: '30s',
+        signal: expect.any(AbortSignal),
+      }
     );
 
     expect(mockDataClient.search).toBeCalledWith(
@@ -1220,7 +1428,11 @@ describe('CsvGenerator', () => {
           max_concurrent_shard_requests: 5,
         },
       },
-      { strategy: 'es', transport: { maxRetries: 0, requestTimeout: '30s' } }
+      {
+        abortSignal: expect.any(AbortSignal),
+        strategy: 'es',
+        transport: { maxRetries: 0, requestTimeout: '30s' },
+      }
     );
   });