Add a temporary shim to ignore spurious Storage events on function deployment. (#128)

Currently, running 'firebase deploy' will result in any Storage events triggering with a spurious (empty) event. This PR introduces a temporary shim in the SDK that will filter out such events, eliding the execution of the user's code.

This shim is sub-optimal, as any filtered events still count as an execution for purposes of UX, but it'll avoid the drawbacks of executing user code with invalid input. This shim will be removed when the backend has stopped sending these spurious events.

Author: Robert-Jan Huijsman

spec/providers/storage.spec.ts

@@ -22,8 +22,8 @@
 
 import * as storage from '../../src/providers/storage';
 import { expect as expect } from 'chai';
-import {fakeConfig} from '../support/helpers';
-import {config} from '../../src/index';
+import { fakeConfig } from '../support/helpers';
+import { config } from '../../src/index';
 
 describe('storage.FunctionBuilder', () => {
   before(() => {
@@ -55,7 +55,7 @@ describe('storage.FunctionBuilder', () => {
       });
     });
 
-    it ('should allow fully qualified bucket names', () => {
+    it('should allow fully qualified bucket names', () => {
       let subjectQualified = new storage.ObjectBuilder('projects/_/buckets/bucky');
       let result = subjectQualified.onChange(() => null);
       expect(result.__trigger).to.deep.equal({
@@ -66,8 +66,43 @@ describe('storage.FunctionBuilder', () => {
       });
     });
 
-    it ('should throw with improperly formatted buckets', () => {
+    it('should throw with improperly formatted buckets', () => {
       expect(() => storage.bucket('bad/bucket/format')).to.throw(Error);
     });
+
+    it('should filter out spurious deploy-time events', () => {
+      let functionRan = false;
+      let cloudFunction = storage.object().onChange(() => {
+        functionRan = true;
+        return null;
+      });
+
+      let spuriousEvent = {
+        timestamp: '2017-03-06T20:02:05.192Z',
+        eventType: 'providers/cloud.storage/eventTypes/object.change',
+        resource: 'projects/_/buckets/rjh-20170306.appspot.com/objects/#0',
+        data: {
+          kind: 'storage#object',
+          resourceState: 'exists',
+          id: 'rjh-20170306.appspot.com//0',
+          selfLink: 'https://www.googleapis.com/storage/v1/b/rjh-20170306.appspot.com/o/',
+          bucket: 'rjh-20170306.appspot.com',
+          generation: '0',
+          metageneration: '0',
+          contentType: '',
+          timeCreated: '1970-01-01T00:00:00.000Z',
+          updated: '1970-01-01T00:00:00.000Z',
+          size: '0',
+          md5Hash: '',
+          mediaLink: 'https://www.googleapis.com/storage/v1/b/rjh-20170306.appspot.com/o/?generation=0&alt=media',
+          crc32c: 'AAAAAA==',
+        },
+        params: {},
+      };
+      return cloudFunction(spuriousEvent).then((result) => {
+        expect(result).equals(null);
+        expect(functionRan).equals(false);
+      });
+    });
   });
 });

src/providers/storage.ts

@@ -21,7 +21,7 @@
 // SOFTWARE.
 
 import { Event, CloudFunction, makeCloudFunction } from '../cloud-functions';
-import {config} from '../index';
+import { config } from '../index';
 
 /** @internal */
 export const provider = 'cloud.storage';
@@ -60,7 +60,19 @@ export class ObjectBuilder {
    * Handle any change to any object.
    */
   onChange(handler: (event: Event<ObjectMetadata>) => PromiseLike<any> | any): CloudFunction<ObjectMetadata> {
-    return makeCloudFunction({provider, handler, resource: this.resource, eventType: 'object.change'});
+    // This is a temporary shim to filter out spurious events due to Functions deployments.
+    // BUG(34123812): clean this up when backend fix for bug is deployed.
+    let filterDeployEvents = (event: Event<ObjectMetadata>) => {
+      if (event.data.timeCreated === '1970-01-01T00:00:00.000Z' && event.data.crc32c === 'AAAAAA==') {
+        console.log(
+          'Function triggered unneccessarily by Cloud Function deployment; function execution elided. ' +
+          'This is a spurious event that will go away soon, sorry for the spam!');
+        return null;
+      }
+      return handler(event);
+    };
+    return makeCloudFunction(
+      { provider, handler: filterDeployEvents, resource: this.resource, eventType: 'object.change' });
   }
 }