Build a Google Chat app behind a firewall with Pub/Sub

Java

• A Business or Enterprise Google Workspace account with access to Google Chat.
• A Google Cloud project with billing enabled. To check that an existing project has billing enabled, see Verify the billing status of your projects. To create a project and set up billing, see Create a Google Cloud project.
• Java 11 or greater
• The Maven package management tool

Python

• A Business or Enterprise Google Workspace account with access to Google Chat.
• A Google Cloud project with billing enabled. To check that an existing project has billing enabled, see Verify the billing status of your projects. To create a project and set up billing, see Create a Google Cloud project.
• Python 3.6 or greater
• The pip package management tool

Node.js

• A Business or Enterprise Google Workspace account with access to Google Chat.
• A Google Cloud project with billing enabled. To check that an existing project has billing enabled, see Verify the billing status of your projects. To create a project and set up billing, see Create a Google Cloud project.
• Node.js 14 or greater
• The npm package management tool
• An initialized Node.js project. To initialize a new project, create and switch into a new folder, then run the following command in your command-line interface:

  npm init

Java

1. In a CLI, provide service account credentials:

   export GOOGLE_APPLICATION_CREDENTIALS=SERVICE_ACCOUNT_FILE_PATH
   

2. In a CLI, provide the Google Cloud project ID:

   export PROJECT_ID=PROJECT_ID
   

3. In a CLI, provide the subscription ID for the Pub/Sub subscription that you previously created:

   export SUBSCRIPTION_ID=SUBSCRIPTION_ID
   

4. In your working directory, create a file named pom.xml.

5. In the pom.xml file, paste the following code:

   java/pub-sub-app/pom.xml

   View on GitHub
   <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
   
     <groupId>com.google.chat</groupId>
     <artifactId>pub-sub-app</artifactId>
     <version>0.1.0</version>
   
     <name>pub-sub-app-java</name>
   
     <properties>
       <maven.compiler.release>21</maven.compiler.release>
       <maven.compiler.source>1.8</maven.compiler.source>
       <maven.compiler.target>1.8</maven.compiler.target>
     </properties>
   
     <dependencies>
       <!-- Google Chat GAPIC library -->
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-google-cloud-chat-v1</artifactId>
         <version>0.8.0</version>
       </dependency>
       <dependency>
         <groupId>com.google.api</groupId>
         <artifactId>gax</artifactId>
         <version>2.48.1</version>
       </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-chat</artifactId>
         <version>0.1.0</version>
       </dependency>
       <!-- Google Cloud Pub/Sub library -->
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-pubsub</artifactId>
       <version>1.125.8</version>
       </dependency>
       <!-- JSON utilities -->
       <dependency>
         <groupId>com.fasterxml.jackson.core</groupId>
         <artifactId>jackson-databind</artifactId>
         <version>2.14.2</version>
       </dependency>
     </dependencies>
   
   </project>

6. In your working directory, create the directory structure src/main/java.

7. In the src/main/java directory, create a file named Main.java.

8. In Main.java, paste the following code:

   java/pub-sub-app/src/main/java/Main.java

   View on GitHub
   import com.fasterxml.jackson.databind.JsonNode;
   import com.fasterxml.jackson.databind.ObjectMapper;
   import com.google.api.gax.core.FixedCredentialsProvider;
   import com.google.auth.oauth2.GoogleCredentials;
   import com.google.chat.v1.ChatServiceClient;
   import com.google.chat.v1.ChatServiceSettings;
   import com.google.chat.v1.CreateMessageRequest;
   import com.google.chat.v1.CreateMessageRequest.MessageReplyOption;
   import com.google.chat.v1.Message;
   import com.google.chat.v1.Thread;
   import com.google.cloud.pubsub.v1.AckReplyConsumer;
   import com.google.cloud.pubsub.v1.MessageReceiver;
   import com.google.cloud.pubsub.v1.Subscriber;
   import com.google.pubsub.v1.ProjectSubscriptionName;
   import com.google.pubsub.v1.PubsubMessage;
   import java.io.FileInputStream;
   import java.util.Collections;
   
   public class Main {
   
     public static final String PROJECT_ID_ENV_PROPERTY = "PROJECT_ID";
     public static final String SUBSCRIPTION_ID_ENV_PROPERTY = "SUBSCRIPTION_ID";
     public static final String CREDENTIALS_PATH_ENV_PROPERTY = "GOOGLE_APPLICATION_CREDENTIALS";
   
     public static void main(String[] args) throws Exception {
       ProjectSubscriptionName subscriptionName = ProjectSubscriptionName.of(
         System.getenv(Main.PROJECT_ID_ENV_PROPERTY),
         System.getenv(Main.SUBSCRIPTION_ID_ENV_PROPERTY));
   
       // Instantiate app, which implements an asynchronous message receiver.
       EchoApp echoApp = new EchoApp();
   
       // Create a subscriber for <var>SUBSCRIPTION_ID</var> bound to the message receiver
       final Subscriber subscriber = Subscriber.newBuilder(subscriptionName, echoApp).build();
       System.out.println("Subscriber is listening to events...");
       subscriber.startAsync();
   
       // Wait for termination
       subscriber.awaitTerminated();
     }
   }
   
   /**
    * A demo app which implements {@link MessageReceiver} to receive messages. It simply echoes the
    * incoming messages.
    */
   class EchoApp implements MessageReceiver {
   
     // Path to the private key JSON file of the service account to be used for posting response
     // messages to Google Chat.
     // In this demo, we are using the same service account for authorizing with Cloud Pub/Sub to
     // receive messages and authorizing with Google Chat to post messages. If you are using
     // different service accounts, please set the path to the private key JSON file of the service
     // account used to post messages to Google Chat here.
     private static final String SERVICE_ACCOUNT_KEY_PATH =
       System.getenv(Main.CREDENTIALS_PATH_ENV_PROPERTY);
   
     // Developer code for Google Chat API scope.
     private static final String GOOGLE_CHAT_API_SCOPE = "https://www.googleapis.com/auth/chat.bot";
   
     private static final String ADDED_RESPONSE = "Thank you for adding me!";
   
     ChatServiceClient chatServiceClient;
   
     EchoApp() throws Exception {
       GoogleCredentials credential = GoogleCredentials
         .fromStream(new FileInputStream(SERVICE_ACCOUNT_KEY_PATH))
         .createScoped(Collections.singleton(GOOGLE_CHAT_API_SCOPE));
   
       // Create the ChatServiceSettings with the app credentials
       ChatServiceSettings chatServiceSettings = ChatServiceSettings.newBuilder()
         .setCredentialsProvider(FixedCredentialsProvider.create(credential)).build();
   
       // Set the Chat service client
       chatServiceClient = ChatServiceClient.create(chatServiceSettings);
     }
   
     // Called when a message is received by the subscriber.
     @Override
     public void receiveMessage(PubsubMessage pubsubMessage, AckReplyConsumer consumer) {
       System.out.println("Id : " + pubsubMessage.getMessageId());
       // Handle incoming message, then ack/nack the received message
       try {
         ObjectMapper mapper = new ObjectMapper();
         JsonNode dataJson = mapper.readTree(pubsubMessage.getData().toStringUtf8());
         System.out.println("Data : " + dataJson.toString());
         handle(dataJson);
         consumer.ack();
       } catch (Exception e) {
         System.out.println(e);
         consumer.nack();
       }
     }
   
     // Send message to Google Chat based on the type of event.
     public void handle(JsonNode eventJson) throws Exception {
       CreateMessageRequest createMessageRequest;
       switch (eventJson.get("type").asText()) {
         case "ADDED_TO_SPACE":
           // An app can also be added to a space by @mentioning it in a message. In that case, we fall
           // through to the MESSAGE case and let the app respond. If the app was added using the
           // invite flow, we just post a thank you message in the space.
           if (!eventJson.has("message")) {
             createMessageRequest = CreateMessageRequest.newBuilder()
               .setParent(eventJson.get("space").get("name").asText())
               .setMessage(Message.newBuilder().setText(ADDED_RESPONSE).build()).build();
             break;
           }
         case "MESSAGE":
           // In case of message, post the response in the same thread.
           createMessageRequest = CreateMessageRequest.newBuilder()
             .setParent(eventJson.get("space").get("name").asText())
             .setMessageReplyOption(MessageReplyOption.REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD)
             .setMessage(Message.newBuilder()
               .setText("You said: `" + eventJson.get("message").get("text").asText() + "`")
               .setThread(Thread.newBuilder()
                 .setName(eventJson.get("message").get("thread").get("name").asText())
                 .build()).build()).build();
           break;
         case "REMOVED_FROM_SPACE":
         default:
           // Do nothing
           return;
       }
   
       // Post the response to Google Chat.
       chatServiceClient.createMessage(createMessageRequest);
     }
   }

Python

1. In a CLI, provide service account credentials:

   export GOOGLE_APPLICATION_CREDENTIALS=SERVICE_ACCOUNT_FILE_PATH
   

2. In a CLI, provide the Google Cloud project ID:

   export PROJECT_ID=PROJECT_ID
   

3. In a CLI, provide the subscription ID for the Pub/Sub subscription that you previously created:

   export SUBSCRIPTION_ID=SUBSCRIPTION_ID
   

4. In your working directory, create a file named requirements.txt.

5. In the requirements.txt file, paste the following code:

   python/pub-sub-app/requirements.txt

   View on GitHub
   google-cloud-pubsub>=2.23.0
   google-apps-chat==0.1.9

6. In your working directory, create a file named app.py.

7. In app.py, paste the following code:

   python/pub-sub-app/app.py

   View on GitHub
   import json
   import logging
   import os
   import sys
   import time
   from google.apps import chat_v1 as google_chat
   from google.cloud import pubsub_v1
   from google.oauth2.service_account import Credentials
   
   
   def receive_messages():
     """Receives messages from a pull subscription."""
   
     scopes = ['https://www.googleapis.com/auth/chat.bot']
     service_account_key_path = os.environ.get(
       'GOOGLE_APPLICATION_CREDENTIALS')
     creds = Credentials.from_service_account_file(
       service_account_key_path)
     chat = google_chat.ChatServiceClient(
       credentials = creds,
       client_options = {
         "scopes": scopes
       })
   
     project_id = os.environ.get('PROJECT_ID')
     subscription_id = os.environ.get('SUBSCRIPTION_ID')
     subscriber = pubsub_v1.SubscriberClient()
     subscription_path = subscriber.subscription_path(
         project_id, subscription_id)
   
     # Handle incoming message, then ack/nack the received message
     def callback(message):
       event = json.loads(message.data)
       logging.info('Data : %s', event)
       space_name = event['space']['name']
   
       # Post the response to Google Chat.
       request = format_request(event)
       if request is not None:
         chat.create_message(request)
   
       # Ack the message.
       message.ack()
   
     subscriber.subscribe(subscription_path, callback = callback)
     logging.info('Listening for messages on %s', subscription_path)
   
     # Keep main thread from exiting while waiting for messages
     while True:
       time.sleep(60)
   
   
   def format_request(event):
     """Send message to Google Chat based on the type of event.
     Args:
       event: A dictionary with the event data.
     """
     space_name = event['space']['name']
     event_type = event['type']
   
     # If the app was removed, we don't respond.
     if event['type'] == 'REMOVED_FROM_SPACE':
       logging.info('App removed rom space %s', space_name)
       return
     elif event_type == 'ADDED_TO_SPACE' and 'message' not in event:
       # An app can also be added to a space by @mentioning it in a
       # message. In that case, we fall through to the message case
       # and let the app respond. If the app was added using the
       # invite flow, we just post a thank you message in the space.
       return google_chat.CreateMessageRequest(
           parent = space_name,
           message = {
             'text': 'Thank you for adding me!'
           }
       )
     elif event_type in ['ADDED_TO_SPACE', 'MESSAGE']:
       # In case of message, post the response in the same thread.
       return google_chat.CreateMessageRequest(
           parent = space_name,
           message_reply_option = google_chat.CreateMessageRequest.MessageReplyOption.REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD,
           message = {
             'text': 'You said: `' + event['message']['text'] + '`',
             'thread': {
               'name': event['message']['thread']['name']
             }
           }
       )
   
   
   if __name__ == '__main__':
     if 'PROJECT_ID' not in os.environ:
       logging.error('Missing PROJECT_ID env var.')
       sys.exit(1)
   
     if 'SUBSCRIPTION_ID' not in os.environ:
       logging.error('Missing SUBSCRIPTION_ID env var.')
       sys.exit(1)
   
     if 'GOOGLE_APPLICATION_CREDENTIALS' not in os.environ:
       logging.error('Missing GOOGLE_APPLICATION_CREDENTIALS env var.')
       sys.exit(1)
   
     logging.basicConfig(
         level=logging.INFO,
         style='{',
         format='{levelname:.1}{asctime} {filename}:{lineno}] {message}')
     receive_messages()

Node.js

1. In a CLI, provide service account credentials:

   export GOOGLE_APPLICATION_CREDENTIALS=SERVICE_ACCOUNT_FILE_PATH
   

2. In a CLI, provide the Google Cloud project ID:

   export PROJECT_ID=PROJECT_ID
   

3. In a CLI, provide the subscription ID for the Pub/Sub subscription that you previously created:

   export SUBSCRIPTION_ID=SUBSCRIPTION_ID
   

4. In your working directory, create a file named package.json.

5. In the package.json file, paste the following code:

   node/pub-sub-app/package.json

   View on GitHub
   {
     "name": "pub-sub-app",
     "version": "1.0.0",
     "description": "Google Chat App that listens for messages via Cloud Pub/Sub",
     "main": "index.js",
     "scripts": {
       "start": "node index.js",
       "test": "echo \"Error: no test specified\" && exit 1"
     },
     "dependencies": {
       "@google-apps/chat": "^0.4.0",
       "@google-cloud/pubsub": "^4.5.0"
     },
     "license": "Apache-2.0"
   }

6. In your working directory, create a file named index.js.

7. In index.js, paste the following code:

   node/pub-sub-app/index.js

   View on GitHub
   const {ChatServiceClient} = require('@google-apps/chat');
   const {MessageReplyOption} = require('@google-apps/chat').protos.google.chat.v1.CreateMessageRequest;
   const {PubSub} = require('@google-cloud/pubsub');
   const {SubscriberClient} = require('@google-cloud/pubsub/build/src/v1');
   
   // Receives messages from a pull subscription.
   function receiveMessages() {
     const chat = new ChatServiceClient({
       keyFile: process.env.GOOGLE_APPLICATION_CREDENTIALS,
       scopes: ['https://www.googleapis.com/auth/chat.bot'],
     });
   
     const subscriptionPath = new SubscriberClient()
       .subscriptionPath(process.env.PROJECT_ID, process.env.SUBSCRIPTION_ID)
     const subscription = new PubSub()
       .subscription(subscriptionPath);
   
     // Handle incoming message, then ack/nack the received message
     const messageHandler = message => {
       console.log(`Id : ${message.id}`);
       const event = JSON.parse(message.data);
       console.log(`Data : ${JSON.stringify(event)}`);
   
       // Post the response to Google Chat.
       const request = formatRequest(event);
       if (request != null) {
         chat.createMessage(request);
       }
   
       // Ack the message.
       message.ack();
     }
   
     subscription.on('message', messageHandler);
     console.log(`Listening for messages on ${subscriptionPath}`);
   
     // Keep main thread from exiting while waiting for messages
     setTimeout(() => {
       subscription.removeListener('message', messageHandler);
       console.log(`Stopped listening for messages.`);
     }, 60 * 1000);
   }
   
   // Send message to Google Chat based on the type of event
   function formatRequest(event) {
     const spaceName = event.space.name;
     const eventType = event.type;
   
     // If the app was removed, we don't respond.
     if (event.type == 'REMOVED_FROM_SPACE') {
       console.log(`App removed rom space ${spaceName}`);
       return null;
     } else if (eventType == 'ADDED_TO_SPACE' && !eventType.message) {
       // An app can also be added to a space by @mentioning it in a
       // message. In that case, we fall through to the message case
       // and let the app respond. If the app was added using the
       // invite flow, we just post a thank you message in the space.
       return {
         parent: spaceName,
         message: { text: 'Thank you for adding me!' }
       };
     } else if (eventType == 'ADDED_TO_SPACE' || eventType == 'MESSAGE') {
       // In case of message, post the response in the same thread.
       return {
         parent: spaceName,
         messageReplyOption: MessageReplyOption.REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD,
         message: {
           text: 'You said: `' + event.message.text + '`',
           thread: { name: event.message.thread.name }
         }
       };
     }
   }
   
   if (!process.env.PROJECT_ID) {
     console.log('Missing PROJECT_ID env var.');
     process.exit(1);
   }
   if (!process.env.SUBSCRIPTION_ID) {
     console.log('Missing SUBSCRIPTION_ID env var.');
     process.exit(1);
   }
   if (!process.env.GOOGLE_APPLICATION_CREDENTIALS) {
     console.log('Missing GOOGLE_APPLICATION_CREDENTIALS env var.');
     process.exit(1);
   }
   
   receiveMessages();

Java

mvn compile exec:java -Dexec.mainClass=Main

Python

python -m venv env
source env/bin/activate
pip install -r requirements.txt -U
python app.py

Node.js

npm install
npm start