feat: added init parameter

README.md

@@ -61,6 +61,10 @@ The `options` property is specific to the chosen transporter. The <strong>GCloud
     <td><code>noAck</code></td>
     <td>If <code>false</code>, manual acknowledgment mode enabled</td>
   </tr>
+  <tr>
+    <td><code>init</code></td>
+    <td>If <code>false</code>, topics and subscriptions will not be created, only validated</td>
+  </tr>
   <tr>
     <td><code>client</code></td>
     <td>Additional client options (read more <a href="https://googleapis.dev/nodejs/pubsub/latest/global.html#ClientConfig" rel="nofollow" target="_blank">here</a>)</td>

lib/gc-pubsub.client.spec.ts

@@ -13,7 +13,10 @@ describe('GCPubSubClient', () => {
 
   beforeEach(() => {
     sandbox = sinon.createSandbox();
-    client = new GCPubSubClient({});
+    client = new GCPubSubClient({
+      replyTopic: 'replyTopic',
+      replySubscription: 'replySubcription',
+    });
 
     subscriptionMock = {
       create: sandbox.stub().resolves(),
@@ -25,6 +28,7 @@ describe('GCPubSubClient', () => {
       create: sandbox.stub().resolves(),
       flush: sandbox.stub().callsFake((callback) => callback()),
       publishMessage: sandbox.stub().resolves(),
+      exists: sandbox.stub().resolves([true]),
       subscription: sandbox.stub().returns(subscriptionMock),
     };
 
@@ -53,6 +57,9 @@ describe('GCPubSubClient', () => {
       it('should call "client.topic" once', async () => {
         expect(pubsub.topic.called).to.be.true;
       });
+      it('should call "topic.exists" once', async () => {
+        expect(topicMock.exists.called).to.be.true;
+      });
       it('should call "topic.create" once', async () => {
         expect(topicMock.create.called).to.be.true;
       });

lib/gc-pubsub.client.ts

@@ -19,10 +19,9 @@ import { ERROR_EVENT, MESSAGE_EVENT } from '@nestjs/microservices/constants';
 import {
   ALREADY_EXISTS,
   GC_PUBSUB_DEFAULT_CLIENT_CONFIG,
+  GC_PUBSUB_DEFAULT_INIT,
   GC_PUBSUB_DEFAULT_NO_ACK,
   GC_PUBSUB_DEFAULT_PUBLISHER_CONFIG,
-  GC_PUBSUB_DEFAULT_REPLY_SUBSCRIPTION,
-  GC_PUBSUB_DEFAULT_REPLY_TOPIC,
   GC_PUBSUB_DEFAULT_SUBSCRIBER_CONFIG,
   GC_PUBSUB_DEFAULT_TOPIC,
 } from './gc-pubsub.constants';
@@ -34,15 +33,16 @@ export class GCPubSubClient extends ClientProxy {
 
   protected readonly topicName: string;
   protected readonly publisherConfig: PublishOptions;
-  protected readonly replyTopicName: string;
+  protected readonly replyTopicName?: string;
+  protected readonly replySubscriptionName?: string;
   protected readonly clientConfig: ClientConfig;
-  protected readonly replySubscriptionName: string;
   protected readonly subscriberConfig: SubscriberOptions;
   protected readonly noAck: boolean;
 
   protected client: PubSub | null = null;
   protected replySubscription: Subscription | null = null;
   protected topic: Topic | null = null;
+  protected init: boolean;
 
   constructor(protected readonly options: GCPubSubOptions) {
     super();
@@ -57,13 +57,12 @@ export class GCPubSubClient extends ClientProxy {
     this.publisherConfig =
       this.options.publisher || GC_PUBSUB_DEFAULT_PUBLISHER_CONFIG;
 
-    this.replyTopicName =
-      this.options.replyTopic || GC_PUBSUB_DEFAULT_REPLY_TOPIC;
+    this.replyTopicName = this.options.replyTopic;
 
-    this.replySubscriptionName =
-      this.options.replySubscription || GC_PUBSUB_DEFAULT_REPLY_SUBSCRIPTION;
+    this.replySubscriptionName = this.options.replySubscription;
 
     this.noAck = this.options.noAck ?? GC_PUBSUB_DEFAULT_NO_ACK;
+    this.init = this.options.init ?? GC_PUBSUB_DEFAULT_INIT;
 
     this.initializeSerializer(options);
     this.initializeDeserializer(options);
@@ -87,27 +86,55 @@ export class GCPubSubClient extends ClientProxy {
 
     this.topic = this.client.topic(this.topicName, this.publisherConfig);
 
-    const replyTopic = this.client.topic(this.replyTopicName);
+    const [topicExists] = await this.topic.exists();
 
-    await this.createIfNotExists(replyTopic.create.bind(replyTopic));
+    if (!topicExists) {
+      const message = `PubSub client is not connected: topic ${this.topicName} does not exist`;
+      this.logger.error(message);
+      throw new Error(message);
+    }
+
+    if (this.replyTopicName && this.replySubscriptionName) {
+      const replyTopic = this.client.topic(this.replyTopicName);
 
-    this.replySubscription = replyTopic.subscription(
-      this.replySubscriptionName,
-      this.subscriberConfig,
-    );
+      if (this.init) {
+        await this.createIfNotExists(replyTopic.create.bind(replyTopic));
+      } else {
+        const [exists] = await replyTopic.exists();
+        if (!exists) {
+          const message = `PubSub client is not connected: topic ${this.replyTopicName} does not exist`;
+          this.logger.error(message);
+          throw new Error(message);
+        }
+      }
 
-    await this.createIfNotExists(
-      this.replySubscription.create.bind(this.replySubscription),
-    );
+      this.replySubscription = replyTopic.subscription(
+        this.replySubscriptionName,
+        this.subscriberConfig,
+      );
 
-    this.replySubscription
-      .on(MESSAGE_EVENT, async (message: Message) => {
-        await this.handleResponse(message.data);
-        if (this.noAck) {
-          message.ack();
+      if (this.init) {
+        await this.createIfNotExists(
+          this.replySubscription.create.bind(this.replySubscription),
+        );
+      } else {
+        const [exists] = await this.replySubscription.exists();
+        if (!exists) {
+          const message = `PubSub client is not connected: subscription ${this.replySubscription} does not exist`;
+          this.logger.error(message);
+          throw new Error(message);
         }
-      })
-      .on(ERROR_EVENT, (err: any) => this.logger.error(err));
+      }
+
+      this.replySubscription
+        .on(MESSAGE_EVENT, async (message: Message) => {
+          await this.handleResponse(message.data);
+          if (this.noAck) {
+            message.ack();
+          }
+        })
+        .on(ERROR_EVENT, (err: any) => this.logger.error(err));
+    }
 
     return this.client;
   }

lib/gc-pubsub.constants.ts

@@ -1,10 +1,8 @@
 export const GC_PUBSUB_DEFAULT_TOPIC = 'default_topic';
-export const GC_PUBSUB_DEFAULT_REPLY_TOPIC = 'default_reply_topic';
 export const GC_PUBSUB_DEFAULT_SUBSCRIPTION = 'default_subscription';
-export const GC_PUBSUB_DEFAULT_REPLY_SUBSCRIPTION =
-  'default_reply_subscription';
 export const GC_PUBSUB_DEFAULT_PUBLISHER_CONFIG = {};
 export const GC_PUBSUB_DEFAULT_SUBSCRIBER_CONFIG = {};
 export const GC_PUBSUB_DEFAULT_CLIENT_CONFIG = {};
 export const GC_PUBSUB_DEFAULT_NO_ACK = true;
+export const GC_PUBSUB_DEFAULT_INIT = true;
 export const ALREADY_EXISTS = 6;

lib/gc-pubsub.interface.ts

@@ -10,6 +10,7 @@ export interface GCPubSubOptions {
   subscription?: string;
   replySubscription?: string;
   noAck?: boolean;
+  init?: boolean
   publisher?: PublishOptions;
   subscriber?: SubscriberOptions;
   serializer?: Serializer;

lib/gc-pubsub.server.ts

@@ -3,7 +3,6 @@ import {
   Message,
   PubSub,
   Subscription,
-  Topic,
 } from '@google-cloud/pubsub';
 import { PublishOptions } from '@google-cloud/pubsub/build/src/publisher';
 import { SubscriberOptions } from '@google-cloud/pubsub/build/src/subscriber';
@@ -26,6 +25,7 @@ import { GCPubSubOptions } from './gc-pubsub.interface';
 import {
   ALREADY_EXISTS,
   GC_PUBSUB_DEFAULT_CLIENT_CONFIG,
+  GC_PUBSUB_DEFAULT_INIT,
   GC_PUBSUB_DEFAULT_NO_ACK,
   GC_PUBSUB_DEFAULT_PUBLISHER_CONFIG,
   GC_PUBSUB_DEFAULT_SUBSCRIBER_CONFIG,
@@ -45,9 +45,9 @@ export class GCPubSubServer extends Server implements CustomTransportStrategy {
   protected readonly subscriberConfig: SubscriberOptions;
   protected readonly noAck: boolean;
   protected readonly replyTopics: Set<string>;
+  protected readonly init: boolean;
 
   protected client: PubSub | null = null;
-  protected readonly topics: Map<string, Topic> = new Map();
   protected subscription: Subscription | null = null;
 
   constructor(protected readonly options: GCPubSubOptions) {
@@ -67,6 +67,7 @@ export class GCPubSubServer extends Server implements CustomTransportStrategy {
       this.options.publisher || GC_PUBSUB_DEFAULT_PUBLISHER_CONFIG;
 
     this.noAck = this.options.noAck ?? GC_PUBSUB_DEFAULT_NO_ACK;
+    this.init = this.options.init ?? GC_PUBSUB_DEFAULT_INIT;
 
     this.replyTopics = new Set();
 
@@ -78,16 +79,34 @@ export class GCPubSubServer extends Server implements CustomTransportStrategy {
     this.client = this.createClient();
     const topic = this.client.topic(this.topicName);
 
-    await this.createIfNotExists(topic.create.bind(topic));
+    if (this.init) {
+      await this.createIfNotExists(topic.create.bind(topic));
+    } else {
+      const [exists] = await topic.exists();
+      if (!exists) {
+        const message = `PubSub server is not started: topic ${this.topicName} does not exist`;
+        this.logger.error(message);
+        throw new Error(message);
+      }
+    }
 
     this.subscription = topic.subscription(
       this.subscriptionName,
       this.subscriberConfig,
     );
 
-    await this.createIfNotExists(
-      this.subscription.create.bind(this.subscription),
-    );
+    if (this.init) {
+      await this.createIfNotExists(
+        this.subscription.create.bind(this.subscription),
+      );
+    } else {
+      const [exists] = await this.subscription.exists();
+      if (!exists) {
+        const message = `PubSub server is not started: subscription ${this.subscriptionName} does not exist`;
+        this.logger.error(message);
+        throw new Error(message);
+      }
+    }
 
     this.subscription
       .on(MESSAGE_EVENT, async (message: Message) => {

tests/src/gc-pubsub-broadcast.controller.ts

@@ -11,6 +11,7 @@ export class GCPubSubBroadcastController implements OnApplicationShutdown {
   constructor() {
     this.client = new GCPubSubClient({
       topic: 'broadcast',
+      replyTopic: 'default_reply_topic',
       replySubscription: 'broadcast_reply_subscription',
       client: {
         apiEndpoint: 'localhost:8681',

tests/src/gc-pubsub.controller.ts

@@ -27,6 +27,8 @@ export class GCPubSubController implements OnApplicationShutdown {
         apiEndpoint: 'localhost:8681',
         projectId: 'microservice',
       },
+      replyTopic: 'default_reply_topic',
+      replySubscription: 'default_reply_subscription',
     });
   }