fix(gcf-utils): cache Cloud Run service URL (#4487)

Because it doesn't change within a single deployment lifecycle.

fixes #4469

packages/gcf-utils/src/gcf-utils.ts

@@ -312,6 +312,7 @@ export class GCFBootstrapper {
   taskTargetName: string;
   taskCaller: string;
   flowControlDelayInSeconds: number;
+  cloudRunURL: string | undefined;
 
   constructor(options?: BootstrapperOptions) {
     options = {
@@ -356,6 +357,7 @@ export class GCFBootstrapper {
     this.taskTargetName = options.taskTargetName || this.functionName;
     this.taskCaller = options.taskCaller || DEFAULT_TASK_CALLER;
     this.flowControlDelayInSeconds = DEFAULT_FLOW_CONTROL_DELAY_IN_SECOND;
+    this.cloudRunURL = undefined;
   }
 
   async loadProbot(
@@ -1070,8 +1072,12 @@ export class GCFBootstrapper {
       // https://us-central1-repo-automation-bots.cloudfunctions.net/merge_on_green
       return `https://${location}-${projectId}.cloudfunctions.net/${botName}`;
     } else if (this.taskTargetEnvironment === 'run') {
+      if (this.cloudRunURL) {
+        return this.cloudRunURL;
+      }
       const url = await this.getCloudRunUrl(projectId, location, botName);
       if (url) {
+        this.cloudRunURL = url;
         return url;
       }
       throw new Error(`Unable to find url for Cloud Run service: ${botName}`);

packages/gcf-utils/test/gcf-bootstrapper.ts

@@ -1791,7 +1791,7 @@ describe('GCFBootstrapper', () => {
       });
     });
 
-    it('queues a Cloud Run URL', async () => {
+    it('queues a Cloud Run URL with caching', async () => {
       const bootstrapper = new GCFBootstrapper({
         projectId: 'my-project',
         functionName: 'my-function-name',
@@ -1831,6 +1831,16 @@ describe('GCFBootstrapper', () => {
       sinon.assert.calledOnceWithExactly(getServiceStub as any, {
         name: 'projects/my-project/locations/my-location/services/my-function-name',
       });
+      // Make sure the Cloud Run service URL is cached.
+      await bootstrapper.enqueueTask({
+        body: JSON.stringify({installation: {id: 1}}),
+        id: 'some-request-id',
+        name: 'event.name',
+      });
+      const getServiceCalls = getServiceStub.getCalls();
+      assert.equal(getServiceCalls.length, 1);
+      const createTaskCalls = createTask.getCalls();
+      assert.equal(createTaskCalls.length, 2);
     });
 
     it('queues a Cloud Run URL with underscored bot name', async () => {