Re-added Migration retries to handle concurrent server startups

Author: sadortun

spec/DefinedSchemas.spec.js

@@ -605,7 +605,7 @@ describe('DefinedSchemas', () => {
 
     expect(logger.error).toHaveBeenCalledWith(`Failed to run migrations: ${error.toString()}`);
   });
-  xit('should perform migration in parallel without failing', async () => {
+  it('should perform migration in parallel without failing', async () => {
     const server = await reconfigureServer();
     const logger = require('../lib/logger').logger;
     spyOn(logger, 'error').and.callThrough();
@@ -632,7 +632,7 @@ describe('DefinedSchemas', () => {
     ]);
 
     const testSchema = (await Parse.Schema.all()).find(
-      ({ className }) => className === migrationOptions.schema[0].className
+      ({ className }) => className === migrationOptions.definitions[0].className
     );
 
     expect(testSchema.indexes.aField).toEqual({ aField: 1 });

src/SchemaMigrations/DefinedSchemas.js

@@ -92,9 +92,18 @@ export class DefinedSchemas {
 
       logger.info('Running Migrations Completed');
     } catch (e) {
-      logger.error(`Failed to run migrations: ${e}`);
-
-      if (this.migrationsOptions.strict) process.exit(1);
+      if (timeout) clearTimeout(timeout);
+      if (this.retries < this.maxRetries) {
+        this.retries++;
+        // first retry 1sec, 2sec, 3sec total 6sec retry sequence
+        // retry will only happen in case of deploying multi parse server instance
+        // at the same time. Modern systems like k8 avoid this by doing rolling updates
+        await this.wait(1000 * this.retries);
+        await this.execute();
+      } else {
+        logger.error(`Failed to run migrations: ${e}`);
+        if (process.env.NODE_ENV === 'production') process.exit(1);
+      }
     }
   }
 
@@ -160,15 +169,13 @@ export class DefinedSchemas {
       try {
         await this.updateSchema(localSchema, cloudSchema);
       } catch (e) {
-        logger.error(`Error during update of schema for type ${cloudSchema.className}: ${e}`);
-        throw e;
+        throw `Error during update of schema for type ${cloudSchema.className}: ${e}`;
       }
     } else {
       try {
         await this.saveSchema(localSchema);
       } catch (e) {
-        logger.error(`Error while saving Schema for type ${localSchema.className}: ${e}`);
-        throw e;
+        throw `Error while saving Schema for type ${localSchema.className}: ${e}`;
       }
     }
   }