[SO Migration] fix reindex race on multi-instance mode

rfcs/text/0013_saved_object_migrations.md

@@ -257,9 +257,11 @@ Note:
 6. Set a write block on the source index. This prevents any further writes from outdated nodes.
 7. Create a new temporary index `.kibana_7.10.0_reindex_temp` with `dynamic: false` on the top-level mappings so that any kind of document can be written to the index. This allows us to write untransformed documents to the index which might have fields which have been removed from the latest mappings defined by the plugin. Define minimal mappings for the `migrationVersion` and `type` fields so that we're still able to search for outdated documents that need to be transformed.
    1. Ignore errors if the target index already exists.
-8. Reindex the source index into the new temporary index.
-   1. Use `op_type=create` `conflicts=proceed` and `wait_for_completion=false` so that multiple instances can perform the reindex in parallel but only one write per document will succeed.
-   2. Wait for the reindex task to complete. If reindexing doesn’t complete within the 60s timeout, log a warning for visibility and poll again.
+8. Reindex the source index into the new temporary index using a 'client-side' reindex, by reading batches of documents from the source, migrating them, and indexing them into the temp index.
+   1. Use `op_type=index` so that multiple instances can perform the reindex in parallel (last node running will override the documents, with no effect as the input data is the same)
+   2. Ignore `version_conflict_engine_exception` exceptions as they just mean that another node was indexing the same documents
+   3. If a `target_index_had_write_block` exception is encountered for all document of a batch, assume that another node already completed the temporary index reindex, and jump to the next step
+   4. If a document transform throws an exception, add the document to a failure list and continue trying to transform all other documents (without writing them to the temp index). If any failures occured, log the complete list of documents that failed to transform, then fail the migration.
 9. Clone the temporary index into the target index `.kibana_7.10.0_001`. Since any further writes will only happen against the cloned target index this prevents a lost delete from occuring where one instance finishes the migration and deletes a document and another instance's reindex operation re-creates the deleted document.
    1. Set a write block on the temporary index
    2. Clone the temporary index into the target index while specifying that the target index should have writes enabled.

src/core/server/saved_objects/migrationsv2/actions/bulk_overwrite_transformed_documents.test.ts

@@ -6,29 +6,96 @@
  * Side Public License, v 1.
  */
 
-import { catchRetryableEsClientErrors } from './catch_retryable_es_client_errors';
+import * as Either from 'fp-ts/Either';
 import { errors as EsErrors } from '@elastic/elasticsearch';
-jest.mock('./catch_retryable_es_client_errors');
 import { elasticsearchClientMock } from '../../../elasticsearch/client/mocks';
+import { catchRetryableEsClientErrors } from './catch_retryable_es_client_errors';
 import { bulkOverwriteTransformedDocuments } from './bulk_overwrite_transformed_documents';
 
+jest.mock('./catch_retryable_es_client_errors');
+
 describe('bulkOverwriteTransformedDocuments', () => {
   beforeEach(() => {
     jest.clearAllMocks();
   });
 
-  // Create a mock client that rejects all methods with a 503 status code
-  // response.
-  const retryableError = new EsErrors.ResponseError(
-    elasticsearchClientMock.createApiResponse({
-      statusCode: 503,
-      body: { error: { type: 'es_type', reason: 'es_reason' } },
-    })
-  );
-  const client = elasticsearchClientMock.createInternalClient(
-    elasticsearchClientMock.createErrorTransportRequestPromise(retryableError)
-  );
+  it('resolves with `right:bulk_index_succeeded` if no error is encountered', async () => {
+    const client = elasticsearchClientMock.createInternalClient(
+      elasticsearchClientMock.createSuccessTransportRequestPromise({
+        items: [
+          {
+            index: {
+              _index: '.dolly',
+            },
+          },
+          {
+            index: {
+              _index: '.dolly',
+            },
+          },
+        ],
+      })
+    );
+
+    const task = bulkOverwriteTransformedDocuments({
+      client,
+      index: 'new_index',
+      transformedDocs: [],
+      refresh: 'wait_for',
+    });
+
+    const result = await task();
+
+    expect(Either.isRight(result)).toBe(true);
+    expect((result as Either.Right<any>).right).toEqual('bulk_index_succeeded');
+  });
+
+  it('resolves with `right:bulk_index_succeeded` if version conflict errors are encountered', async () => {
+    const client = elasticsearchClientMock.createInternalClient(
+      elasticsearchClientMock.createSuccessTransportRequestPromise({
+        items: [
+          {
+            index: {
+              _index: '.dolly',
+            },
+          },
+          {
+            index: {
+              error: {
+                type: 'version_conflict_engine_exception',
+                reason: 'reason',
+              },
+            },
+          },
+        ],
+      })
+    );
+
+    const task = bulkOverwriteTransformedDocuments({
+      client,
+      index: 'new_index',
+      transformedDocs: [],
+      refresh: 'wait_for',
+    });
+
+    const result = await task();
+
+    expect(Either.isRight(result)).toBe(true);
+    expect((result as Either.Right<any>).right).toEqual('bulk_index_succeeded');
+  });
+
   it('calls catchRetryableEsClientErrors when the promise rejects', async () => {
+    // Create a mock client that rejects all methods with a 503 status code response.
+    const retryableError = new EsErrors.ResponseError(
+      elasticsearchClientMock.createApiResponse({
+        statusCode: 503,
+        body: { error: { type: 'es_type', reason: 'es_reason' } },
+      })
+    );
+    const client = elasticsearchClientMock.createInternalClient(
+      elasticsearchClientMock.createErrorTransportRequestPromise(retryableError)
+    );
+
     const task = bulkOverwriteTransformedDocuments({
       client,
       index: 'new_index',
@@ -43,4 +110,93 @@ describe('bulkOverwriteTransformedDocuments', () => {
 
     expect(catchRetryableEsClientErrors).toHaveBeenCalledWith(retryableError);
   });
+
+  it('resolves with `left:target_index_had_write_block` if all errors are write block exceptions', async () => {
+    const client = elasticsearchClientMock.createInternalClient(
+      elasticsearchClientMock.createSuccessTransportRequestPromise({
+        items: [
+          {
+            index: {
+              error: {
+                type: 'cluster_block_exception',
+                reason:
+                  'index [.kibana_9000] blocked by: [FORBIDDEN/8/moving to block index write (api)]',
+              },
+            },
+          },
+          {
+            index: {
+              error: {
+                type: 'cluster_block_exception',
+                reason:
+                  'index [.kibana_9000] blocked by: [FORBIDDEN/8/moving to block index write (api)]',
+              },
+            },
+          },
+        ],
+      })
+    );
+
+    const task = bulkOverwriteTransformedDocuments({
+      client,
+      index: 'new_index',
+      transformedDocs: [],
+      refresh: 'wait_for',
+    });
+
+    const result = await task();
+
+    expect(Either.isLeft(result)).toBe(true);
+    expect((result as Either.Left<any>).left).toEqual({
+      type: 'target_index_had_write_block',
+    });
+  });
+
+  it('throws an error if any error is not a write block exceptions', async () => {
+    (catchRetryableEsClientErrors as jest.Mock).mockImplementation((e) => {
+      throw e;
+    });
+
+    const client = elasticsearchClientMock.createInternalClient(
+      elasticsearchClientMock.createSuccessTransportRequestPromise({
+        items: [
+          {
+            index: {
+              error: {
+                type: 'cluster_block_exception',
+                reason:
+                  'index [.kibana_9000] blocked by: [FORBIDDEN/8/moving to block index write (api)]',
+              },
+            },
+          },
+          {
+            index: {
+              error: {
+                type: 'dolly_exception',
+                reason: 'because',
+              },
+            },
+          },
+          {
+            index: {
+              error: {
+                type: 'cluster_block_exception',
+                reason:
+                  'index [.kibana_9000] blocked by: [FORBIDDEN/8/moving to block index write (api)]',
+              },
+            },
+          },
+        ],
+      })
+    );
+
+    const task = bulkOverwriteTransformedDocuments({
+      client,
+      index: 'new_index',
+      transformedDocs: [],
+      refresh: 'wait_for',
+    });
+
+    await expect(task()).rejects.toThrow();
+  });
 });

src/core/server/saved_objects/migrationsv2/actions/bulk_overwrite_transformed_documents.ts

@@ -15,7 +15,9 @@ import {
   catchRetryableEsClientErrors,
   RetryableEsClientError,
 } from './catch_retryable_es_client_errors';
+import { isWriteBlockException } from './es_errors';
 import { WAIT_FOR_ALL_SHARDS_TO_BE_ACTIVE } from './constants';
+import type { TargetIndexHadWriteBlock } from './index';
 
 /** @internal */
 export interface BulkOverwriteTransformedDocumentsParams {
@@ -24,6 +26,7 @@ export interface BulkOverwriteTransformedDocumentsParams {
   transformedDocs: SavedObjectsRawDoc[];
   refresh?: estypes.Refresh;
 }
+
 /**
  * Write the up-to-date transformed documents to the index, overwriting any
  * documents that are still on their outdated version.
@@ -34,7 +37,7 @@ export const bulkOverwriteTransformedDocuments = ({
   transformedDocs,
   refresh = false,
 }: BulkOverwriteTransformedDocumentsParams): TaskEither.TaskEither<
-  RetryableEsClientError,
+  RetryableEsClientError | TargetIndexHadWriteBlock,
   'bulk_index_succeeded'
 > => () => {
   return client
@@ -71,12 +74,19 @@ export const bulkOverwriteTransformedDocuments = ({
     .then((res) => {
       // Filter out version_conflict_engine_exception since these just mean
       // that another instance already updated these documents
-      const errors = (res.body.items ?? []).filter(
-        (item) => item.index?.error?.type !== 'version_conflict_engine_exception'
-      );
+      const errors = (res.body.items ?? [])
+        .filter((item) => item.index?.error)
+        .map((item) => item.index!.error!)
+        .filter(({ type }) => type !== 'version_conflict_engine_exception');
+
       if (errors.length === 0) {
         return Either.right('bulk_index_succeeded' as const);
       } else {
+        if (errors.every(isWriteBlockException)) {
+          return Either.left({
+            type: 'target_index_had_write_block' as const,
+          });
+        }
         throw new Error(JSON.stringify(errors));
       }
     })

src/core/server/saved_objects/migrationsv2/actions/es_errors.test.ts

@@ -0,0 +1,56 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { isIncompatibleMappingException, isWriteBlockException } from './es_errors';
+
+describe('isWriteBlockError', () => {
+  it('returns true for a `index write` cluster_block_exception', () => {
+    expect(
+      isWriteBlockException({
+        type: 'cluster_block_exception',
+        reason: `index [.kibana_dolly] blocked by: [FORBIDDEN/8/index write (api)]`,
+      })
+    ).toEqual(true);
+  });
+  it('returns true for a `moving to block index write` cluster_block_exception', () => {
+    expect(
+      isWriteBlockException({
+        type: 'cluster_block_exception',
+        reason: `index [.kibana_dolly] blocked by: [FORBIDDEN/8/moving to block index write (api)]`,
+      })
+    ).toEqual(true);
+  });
+  it('returns false for incorrect type', () => {
+    expect(
+      isWriteBlockException({
+        type: 'not_a_cluster_block_exception_at_all',
+        reason: `index [.kibana_dolly] blocked by: [FORBIDDEN/8/index write (api)]`,
+      })
+    ).toEqual(false);
+  });
+});
+
+describe('isIncompatibleMappingExceptionError', () => {
+  it('returns true for `strict_dynamic_mapping_exception` errors', () => {
+    expect(
+      isIncompatibleMappingException({
+        type: 'strict_dynamic_mapping_exception',
+        reason: 'idk',
+      })
+    ).toEqual(true);
+  });
+
+  it('returns true for `mapper_parsing_exception` errors', () => {
+    expect(
+      isIncompatibleMappingException({
+        type: 'mapper_parsing_exception',
+        reason: 'idk',
+      })
+    ).toEqual(true);
+  });
+});

src/core/server/saved_objects/migrationsv2/actions/es_errors.ts

@@ -0,0 +1,23 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+export interface EsErrorCause {
+  type: string;
+  reason: string;
+}
+
+export const isWriteBlockException = ({ type, reason }: EsErrorCause): boolean => {
+  return (
+    type === 'cluster_block_exception' &&
+    reason.match(/index \[.+] blocked by: \[FORBIDDEN\/8\/.+ \(api\)\]/) !== null
+  );
+};
+
+export const isIncompatibleMappingException = ({ type }: EsErrorCause): boolean => {
+  return type === 'strict_dynamic_mapping_exception' || type === 'mapper_parsing_exception';
+};

src/core/server/saved_objects/migrationsv2/actions/integration_tests/actions.test.ts

@@ -188,7 +188,14 @@ describe('migration actions', () => {
           transformedDocs: sourceDocs,
           refresh: 'wait_for',
         })()
-      ).rejects.toMatchObject(expect.anything());
+      ).resolves.toMatchInlineSnapshot(`
+              Object {
+                "_tag": "Left",
+                "left": Object {
+                  "type": "target_index_had_write_block",
+                },
+              }
+            `);
     });
     it('resolves left index_not_found_exception when the index does not exist', async () => {
       expect.assertions(1);
@@ -1496,7 +1503,7 @@ describe('migration actions', () => {
                 }
               `);
     });
-    it('rejects if there are errors', async () => {
+    it('resolves left if there are write_block errors', async () => {
       const newDocs = ([
         { _source: { title: 'doc 5' } },
         { _source: { title: 'doc 6' } },
@@ -1509,7 +1516,14 @@ describe('migration actions', () => {
           transformedDocs: newDocs,
           refresh: 'wait_for',
         })()
-      ).rejects.toMatchObject(expect.anything());
+      ).resolves.toMatchInlineSnapshot(`
+              Object {
+                "_tag": "Left",
+                "left": Object {
+                  "type": "target_index_had_write_block",
+                },
+              }
+            `);
     });
   });
 });