Make CHECK_UNKONWN_DOCUMENTS step log warning instead of failing

src/core/server/saved_objects/migrationsv2/migrations_state_action_machine.ts

@@ -52,6 +52,8 @@ const logStateTransition = (
       switch (level) {
         case 'error':
           return logger.error(logMessagePrefix + message);
+        case 'warning':
+          return logger.warn(logMessagePrefix + message);
         case 'info':
           return logger.info(logMessagePrefix + message);
         default:

src/core/server/saved_objects/migrationsv2/model/extract_errors.test.ts

@@ -25,7 +25,7 @@ describe('extractUnknownDocFailureReason', () => {
         '.kibana_15'
       )
     ).toMatchInlineSnapshot(`
-      "Migration failed because documents were found for unknown saved object types. To proceed with the migration, please delete these documents from the \\".kibana_15\\" index.
+      "Upgrades will fail for 8.0+ because documents were found for unknown saved object types. To ensure that upgrades will succeed in the future, either re-enable plugins or delete these documents from the \\".kibana_15\\" index after the current upgrade completes.
       The documents with unknown types are:
       - \\"unknownType:12\\" (type: \\"unknownType\\")
       - \\"anotherUnknownType:42\\" (type: \\"anotherUnknownType\\")

src/core/server/saved_objects/migrationsv2/model/extract_errors.ts

@@ -38,15 +38,16 @@ export function extractTransformFailuresReason(
 
 export function extractUnknownDocFailureReason(
   unknownDocs: CheckForUnknownDocsFoundDoc[],
-  sourceIndex: string
+  targetIndex: string
 ): string {
   return (
-    `Migration failed because documents were found for unknown saved object types. ` +
-    `To proceed with the migration, please delete these documents from the "${sourceIndex}" index.\n` +
+    `Upgrades will fail for 8.0+ because documents were found for unknown saved object types. ` +
+    `To ensure that upgrades will succeed in the future, either re-enable plugins or delete these documents from the ` +
+    `"${targetIndex}" index after the current upgrade completes.\n` +
     `The documents with unknown types are:\n` +
     unknownDocs.map((doc) => `- "${doc.id}" (type: "${doc.type}")\n`).join('') +
     `You can delete them using the following command:\n` +
-    `curl -X POST "{elasticsearch}/${sourceIndex}/_bulk?pretty" -H 'Content-Type: application/json' -d'\n` +
+    `curl -X POST "{elasticsearch}/${targetIndex}/_bulk?pretty" -H 'Content-Type: application/json' -d'\n` +
     unknownDocs.map((doc) => `{ "delete" : { "_id" : "${doc.id}" } }\n`).join('') +
     `'`
   );

src/core/server/saved_objects/migrationsv2/model/model.test.ts

@@ -760,7 +760,7 @@ describe('migrations v2 model', () => {
         `);
       });
 
-      test('CHECK_UNKNOWN_DOCUMENTS -> FATAL if action fails and unknown docs were found', () => {
+      test('CHECK_UNKNOWN_DOCUMENTS -> SET_SOURCE_WRITE_BLOCK and adds logs if action fails and unknown docs were found', () => {
         const checkUnknownDocumentsSourceState: CheckUnknownDocumentsState = {
           ...baseState,
           controlState: 'CHECK_UNKNOWN_DOCUMENTS',
@@ -776,12 +776,44 @@ describe('migrations v2 model', () => {
           ],
         });
         const newState = model(checkUnknownDocumentsSourceState, res);
-        expect(newState.controlState).toEqual('FATAL');
+        expect(newState.controlState).toEqual('SET_SOURCE_WRITE_BLOCK');
 
         expect(newState).toMatchObject({
-          controlState: 'FATAL',
-          reason: expect.stringContaining(
-            'Migration failed because documents were found for unknown saved object types'
+          controlState: 'SET_SOURCE_WRITE_BLOCK',
+          sourceIndex: Option.some('.kibana_3'),
+          targetIndex: '.kibana_7.11.0_001',
+        });
+
+        // This snapshot asserts that we disable the unknown saved object
+        // type. Because it's mappings are disabled, we also don't copy the
+        // `_meta.migrationMappingPropertyHashes` for the disabled type.
+        expect(newState.targetIndexMappings).toMatchInlineSnapshot(`
+          Object {
+            "_meta": Object {
+              "migrationMappingPropertyHashes": Object {
+                "new_saved_object_type": "4a11183eee21e6fbad864f7a30b39ad0",
+              },
+            },
+            "properties": Object {
+              "disabled_saved_object_type": Object {
+                "dynamic": false,
+                "properties": Object {},
+              },
+              "new_saved_object_type": Object {
+                "properties": Object {
+                  "value": Object {
+                    "type": "text",
+                  },
+                },
+              },
+            },
+          }
+        `);
+
+        expect(newState.logs[0]).toMatchObject({
+          level: 'warning',
+          message: expect.stringContaining(
+            'Upgrades will fail for 8.0+ because documents were found for unknown saved object types'
           ),
         });
       });

src/core/server/saved_objects/migrationsv2/model/model.ts

@@ -318,31 +318,42 @@ export const model = (currentState: State, resW: ResponseType<AllActionStates>):
     }
   } else if (stateP.controlState === 'CHECK_UNKNOWN_DOCUMENTS') {
     const res = resW as ExcludeRetryableEsError<ResponseType<typeof stateP.controlState>>;
+
+    const source = stateP.sourceIndex;
+    const target = stateP.versionIndex;
+    const nextState: State = {
+      ...stateP,
+      controlState: 'SET_SOURCE_WRITE_BLOCK',
+      sourceIndex: source,
+      targetIndex: target,
+      targetIndexMappings: disableUnknownTypeMappingFields(
+        stateP.targetIndexMappings,
+        stateP.sourceIndexMappings
+      ),
+      versionIndexReadyActions: Option.some<AliasAction[]>([
+        { remove: { index: source.value, alias: stateP.currentAlias, must_exist: true } },
+        { add: { index: target, alias: stateP.currentAlias } },
+        { add: { index: target, alias: stateP.versionAlias } },
+        { remove_index: { index: stateP.tempIndex } },
+      ]),
+    };
+
     if (Either.isRight(res)) {
-      const source = stateP.sourceIndex;
-      const target = stateP.versionIndex;
-      return {
-        ...stateP,
-        controlState: 'SET_SOURCE_WRITE_BLOCK',
-        sourceIndex: source,
-        targetIndex: target,
-        targetIndexMappings: disableUnknownTypeMappingFields(
-          stateP.targetIndexMappings,
-          stateP.sourceIndexMappings
-        ),
-        versionIndexReadyActions: Option.some<AliasAction[]>([
-          { remove: { index: source.value, alias: stateP.currentAlias, must_exist: true } },
-          { add: { index: target, alias: stateP.currentAlias } },
-          { add: { index: target, alias: stateP.versionAlias } },
-          { remove_index: { index: stateP.tempIndex } },
-        ]),
-      };
+      return nextState;
     } else {
       if (isLeftTypeof(res.left, 'unknown_docs_found')) {
         return {
-          ...stateP,
-          controlState: 'FATAL',
-          reason: extractUnknownDocFailureReason(res.left.unknownDocs, stateP.sourceIndex.value),
+          ...nextState,
+          logs: [
+            ...nextState.logs,
+            {
+              level: 'warning',
+              message: `CHECK_UNKNOWN_DOCUMENTS ${extractUnknownDocFailureReason(
+                res.left.unknownDocs,
+                target
+              )}`,
+            },
+          ],
         };
       } else {
         return throwBadResponse(stateP, res.left);

src/core/server/saved_objects/migrationsv2/types.ts

@@ -19,7 +19,7 @@ import {
   DocumentsTransformSuccess,
 } from '../migrations/core/migrate_raw_docs';
 
-export type MigrationLogLevel = 'error' | 'info';
+export type MigrationLogLevel = 'error' | 'info' | 'warning';
 
 export interface MigrationLog {
   level: MigrationLogLevel;