Build an HTTP Google Chat app with Cloud Functions

This page explains how to create an HTTP Chat app. There are different ways to implement this architecture. On Google Cloud, you can use Cloud Functions, Cloud Run, and App Engine. In this quickstart, you write and deploy a Cloud Function that the Chat app uses to respond to a user's message.

With this architecture, you configure Chat to integrate with Google Cloud or an on-premises server by using HTTP, as shown in the following diagram:

Architecture of a Chat app using a web service in an on-premises server.

In the preceding diagram, a user interacting with an HTTP Chat app has the following flow of information:

  1. A user sends a message in Chat to a Chat app, either in a direct message or in a Chat space.
  2. An HTTP request is sent to a web server that is either a cloud or on-premises system that contains the Chat app logic.
  3. Optionally, the Chat app logic can integrate with Google Workspace services (like Calendar and Sheets), other Google services (like Maps, YouTube, and Vertex AI), or other web services (like a project management system or ticketing tool).
  4. The web server sends an HTTP response back to the Chat app service in Chat.
  5. The response is delivered to the user.
  6. Optionally, the Chat app can call the Chat API to asynchronously post messages or perform other operations.

This architecture provides you the flexibility to use existing libraries and components that already exist in your system because these Chat apps can be designed using different programming languages.

Objectives

  • Set up your environment.
  • Create and deploy a Cloud Function.
  • Publish the app to Chat.
  • Test the app.

Prerequisites

  • A Google Workspace account with access to Google Chat in a Google Workspace organization that permits unauthenticated Google Cloud Function invocations.

Set up the environment

Before using Google APIs, you need to turn them on in a Google Cloud project. You can turn on one or more APIs in a single Google Cloud project.
  • In the Google Cloud console, enable the Google Chat API, Cloud Build API, Cloud Functions API, Cloud Pub/Sub API, Cloud Logging API, Artifact Registry API, and Cloud Run API.

    Enable the APIs

Create and deploy a Cloud Function

Create and deploy a Cloud Function that generates a Chat card with the sender's display name and avatar image. When the Chat app receives a message, it runs the function and responds with the card.

To create and deploy the function for your Chat app, complete the following steps:

Node.js

  1. In the Google Cloud console, go to the Cloud Functions page:

    Go to Cloud Functions

    Make sure that the project for your Chat app is selected.

  2. Click Create Function.

  3. On the Create function page, set up your function:

    1. In Environment, select 2nd gen.
    2. In Function name, enter QuickStartChatApp.
    3. In Region, select a region.
    4. Under Authentication, select Allow unauthenticated invocations.
    5. Click Next.
  4. In Runtime, select Node.js 20.

  5. In Source code, select Inline Editor.

  6. In Entry point, delete the default text and enter helloChat.

  7. Replace the contents of index.js with the following code:

    node/avatar-app/index.js
    /**
     * Google Cloud Function that responds to messages sent from a
     * Google Chat room.
     *
     * @param {Object} req Request sent from Google Chat room
     * @param {Object} res Response to send back
     */
    exports.helloChat = function helloChat(req, res) {
      if (req.method === 'GET' || !req.body.message) {
        res.send('Hello! This function is meant to be used in a Google Chat ' +
          'Room.');
      }
    
      const sender = req.body.message.sender.displayName;
      const image = req.body.message.sender.avatarUrl;
    
      const data = createMessage(sender, image);
    
      res.send(data);
    };
    
    /**
     * Creates a card with two widgets.
     * @param {string} displayName the sender's display name
     * @param {string} imageUrl the URL for the sender's avatar
     * @return {Object} a card with the user's avatar.
     */
    function createMessage(displayName, imageUrl) {
      const cardHeader = {
        title: `Hello ${displayName}!`,
      };
    
      const avatarWidget = {
        textParagraph: {text: 'Your avatar picture: '},
      };
    
      const avatarImageWidget = {
        image: {imageUrl},
      };
    
      const avatarSection = {
        widgets: [
          avatarWidget,
          avatarImageWidget,
        ],
      };
    
      return {
        text: 'Here\'s your avatar',
        cardsV2: [{
          cardId: 'avatarCard',
          card: {
            name: 'Avatar Card',
            header: cardHeader,
            sections: [avatarSection],
          }
        }],
      };
    }

  8. Click Deploy.

Python

  1. In the Google Cloud console, go to the Cloud Functions page:

    Go to Cloud Functions

    Make sure that the project for your Chat app is selected.

  2. Click Create Function.

  3. On the Create function page, set up your function:

    1. In Function name, enter QuickStartChatApp.
    2. In Trigger type, select HTTP.
    3. Under Authentication, select Allow unauthenticated invocations.
    4. Click Save.
    5. Click Next.
  4. In Runtime, select Python 3.10.

  5. In Source code, select Inline Editor.

  6. In Entry point, delete the default text and enter hello_chat.

  7. Replace the contents of main.py with the following code:

    python/avatar-app/main.py
    from typing import Any, Mapping
    
    import flask
    import functions_framework
    
    
    # Google Cloud Function that responds to messages sent in
    # Google Chat.
    #
    # @param {Object} req Request sent from Google Chat.
    # @param {Object} res Response to send back.
    @functions_framework.http
    def hello_chat(req: flask.Request) -> Mapping[str, Any]:
      if req.method == "GET":
        return "Hello! This function must be called from Google Chat."
    
      request_json = req.get_json(silent=True)
    
      display_name = request_json["message"]["sender"]["displayName"]
      avatar = request_json["message"]["sender"]["avatarUrl"]
    
      response = create_message(name=display_name, image_url=avatar)
    
      return response
    
    
    # Creates a card with two widgets.
    # @param {string} name the sender's display name.
    # @param {string} image_url the URL for the sender's avatar.
    # @return {Object} a card with the user's avatar.
    def create_message(name: str, image_url: str) -> Mapping[str, Any]:
      avatar_image_widget = {"image": {"imageUrl": image_url}}
      avatar_text_widget = {"textParagraph": {"text": "Your avatar picture:"}}
      avatar_section = {"widgets": [avatar_text_widget, avatar_image_widget]}
    
      header = {"title": f"Hello {name}!"}
    
      cards = {
          "text": "Here's your avatar",
          "cardsV2": [
              {
                  "cardId": "avatarCard",
                  "card": {
                      "name": "Avatar Card",
                      "header": header,
                      "sections": [avatar_section],
                  },
              }
          ]
      }
    
      return cards

  8. Click Deploy.

Java

  1. In the Google Cloud console, go to the Cloud Functions page:

    Go to Cloud Functions

    Make sure that the project for your Chat app is selected.

  2. Click Create Function.

  3. On the Create function page, set up your function:

    1. In Function name, enter QuickStartChatApp.
    2. In Trigger type, select HTTP.
    3. Under Authentication, select Allow unauthenticated invocations.
    4. Click Save.
    5. Click Next.
  4. In Runtime, select Java 11.

  5. In Source code, select Inline Editor.

  6. In Entry point, delete the default text and enter HelloChat.

  7. Rename src/main/java/com/example/Example.java to src/main/java/HelloChat.java.

  8. Replace the contents of HelloChat.java with the following code:

    java/avatar-app/src/main/java/HelloChat.java
    import com.google.api.services.chat.v1.model.CardWithId;
    import com.google.api.services.chat.v1.model.GoogleAppsCardV1Card;
    import com.google.api.services.chat.v1.model.GoogleAppsCardV1CardHeader;
    import com.google.api.services.chat.v1.model.GoogleAppsCardV1Image;
    import com.google.api.services.chat.v1.model.GoogleAppsCardV1Section;
    import com.google.api.services.chat.v1.model.GoogleAppsCardV1TextParagraph;
    import com.google.api.services.chat.v1.model.GoogleAppsCardV1Widget;
    import com.google.api.services.chat.v1.model.Message;
    import com.google.cloud.functions.HttpFunction;
    import com.google.cloud.functions.HttpRequest;
    import com.google.cloud.functions.HttpResponse;
    import com.google.gson.Gson;
    import com.google.gson.JsonObject;
    import java.util.List;
    
    public class HelloChat implements HttpFunction {
      private static final Gson gson = new Gson();
    
      @Override
      public void service(HttpRequest request, HttpResponse response) throws Exception {
        JsonObject body = gson.fromJson(request.getReader(), JsonObject.class);
    
        if (request.getMethod().equals("GET") || !body.has("message")) {
          response.getWriter().write("Hello! This function must be called from Google Chat.");
          return;
        }
    
        JsonObject sender = body.getAsJsonObject("message").getAsJsonObject("sender");
        String displayName = sender.has("displayName") ? sender.get("displayName").getAsString() : "";
        String avatarUrl = sender.has("avatarUrl") ? sender.get("avatarUrl").getAsString() : "";
        Message message = createMessage(displayName, avatarUrl);
    
        response.getWriter().write(gson.toJson(message));
      }
    
      Message createMessage(String displayName, String avatarUrl) {
        GoogleAppsCardV1CardHeader cardHeader = new GoogleAppsCardV1CardHeader();
        cardHeader.setTitle(String.format("Hello %s!", displayName));
    
        GoogleAppsCardV1TextParagraph textParagraph = new GoogleAppsCardV1TextParagraph();
        textParagraph.setText("Your avatar picture: ");
    
        GoogleAppsCardV1Widget avatarWidget = new GoogleAppsCardV1Widget();
        avatarWidget.setTextParagraph(textParagraph);
    
        GoogleAppsCardV1Image image = new GoogleAppsCardV1Image();
        image.setImageUrl(avatarUrl);
    
        GoogleAppsCardV1Widget avatarImageWidget = new GoogleAppsCardV1Widget();
        avatarImageWidget.setImage(image);
    
        GoogleAppsCardV1Section section = new GoogleAppsCardV1Section();
        section.setWidgets(List.of(avatarWidget, avatarImageWidget));
    
        GoogleAppsCardV1Card card = new GoogleAppsCardV1Card();
        card.setName("Avatar Card");
        card.setHeader(cardHeader);
        card.setSections(List.of(section));
    
        CardWithId cardWithId = new CardWithId();
        cardWithId.setCardId("previewLink");
        cardWithId.setCard(card);
    
        Message message = new Message();
        message.setText("Here's your avatar");
        message.setCardsV2(List.of(cardWithId));
    
        return message;
      }
    }

  9. Replace the contents of pom.xml with the following code:

    java/avatar-app/pom.xml
    <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>cloudfunctions</groupId>
      <artifactId>http-function</artifactId>
      <version>1.0-SNAPSHOT</version>
    
      <properties>
        <maven.compiler.target>11</maven.compiler.target>
        <maven.compiler.source>11</maven.compiler.source>
      </properties>
    
      <dependencies>
        <dependency>
          <groupId>com.google.cloud.functions</groupId>
          <artifactId>functions-framework-api</artifactId>
          <version>1.0.1</version>
        </dependency>
    
        <!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.9.1</version>
        </dependency>
    
        <!-- https://mvnrepository.com/artifact/com.google.apis/google-api-services-chat -->
        <dependency>
          <groupId>com.google.apis</groupId>
          <artifactId>google-api-services-chat</artifactId>
          <version>v1-rev20230115-2.0.0</version>
        </dependency>
      </dependencies>
    
      <!-- Required for Java 11 functions in the inline editor -->
      <build>
        <plugins>
          <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
            <configuration>
              <excludes>
                <exclude>.google/</exclude>
              </excludes>
            </configuration>
          </plugin>
        </plugins>
      </build>
    </project>

  10. Click Deploy.

The Cloud Functions detail page opens, and your function appears with two progress indicators: one for the build and one for the service. When both progress indicators disappear and are replaced with a check mark, your function is deployed and ready.

Publish the app to Google Chat

After the Cloud Function is deployed, follow these steps to turn it into a Google Chat app:

  1. In the Google Cloud console, click Menu > Cloud Functions.

    Go to Cloud Functions

    Make sure that the project for which you enabled Cloud Functions is selected.

  2. In the list of functions, click QuickStartChatApp.

  3. On the Function details page, click Trigger.

  4. Under Trigger URL, copy the URL.

  5. Search for "Google Chat API" and click Google Chat API, then click Manage.

    Go to Chat API

  6. Click Configuration and set up the Google Chat app:

    1. In App name, enter Quickstart App.
    2. In Avatar URL, enter https://developers.google.com/chat/images/quickstart-app-avatar.png.
    3. In Description, enter Quickstart app.
    4. Under Functionality, select Receive 1:1 messages and Join spaces and group conversations.
    5. Under Connection settings, select App URL and paste the URL for the Cloud Function trigger into the box.
    6. Under Visibility, select Make this Google Chat app available to specific people and groups in your domain and enter your email address.
    7. Under Logs, select Log errors to Logging.
  7. Click Save.

The Chat app is ready to receive and respond to messages on Chat.

Test your Chat app

To test your Chat app, send the app a direct message:

  1. Open Google Chat.
  2. To send a direct message to the app, click Start a chat , and in the window that appears, click Find apps.
  3. In the Find apps dialog, search for Quickstart App.
  4. To open a direct message with the app, find the Quickstart App and click Add > Chat.
  5. In the direct message, type Hello and press enter.

The Chat app's response contains a card message that displays the sender's name and avatar image, as demonstrated in the following image:

Chat app responding with a card featuring the sender's display name and avatar
image

To add trusted testers and learn more about testing interactive features, see Test interactive features for Google Chat apps.

Troubleshoot errors

To troubleshoot and debug your Chat app, see Troubleshoot and fix Google Chat app errors.