Build an HTTP Google Chat app

This page explains how to build a Google Workspace add-on that works in Google Chat using an HTTP service. In Google Chat, add-ons appear to users as Google Chat apps. To learn more, see the Extend Google Chat overview.

This quickstart shows you how to build an HTTP service using Google Cloud services. To build the Chat app, you write and deploy a Cloud Function that the Chat app uses to respond to a user's message.

With an HTTP 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:

A user sends a message in Chat to a Chat app, either in a direct message or in a Chat space.
An HTTP request is sent to a web server that is either a cloud or on-premises system that contains the Chat app logic.
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).
The web server sends an HTTP response back to the Chat app service in Chat.
The response is delivered to the user.
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.
Configure a Google Workspace add-on for the Chat app.
Test the app.

Prerequisites

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.

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.

You must also enable the Google Workspace add-ons API but you can't use this API to create and manage deployments of the Chat app. For details, see Limitations and known issues.

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

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.
Click Create Function.
On the Create function page, set up your function:
1. In Environment, select Cloud Run Function.
2. In Function name, enter AddOnChatApp.
3. In Region, select a region.
4. Under Authentication, select Require authentication.
5. Click Next.
In Runtime, select the most recent version of Node.js.
In Source code, select Inline Editor.
In Entry point, delete the default text and enter avatarApp.

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

/**
 * Google Cloud Function that responds to messages sent from a
 * Google Chat space.
 *
 * @param {Object} req Request sent from Google Chat space
 * @param {Object} res Response to send back
 */
exports.avatarApp = function avatarApp(req, res) {
    if (req.method === 'GET' || !req.body.chat) {
        return res.send('Hello! This function is meant to be used ' +
            'in a Google Chat Space.');
    }

    // Stores the Google Chat event as a variable.
    const chatMessage = req.body.chat.messagePayload.message;

    // Replies with the sender's avatar in a card.
    const displayName = chatMessage.sender.displayName;
    const avatarUrl = chatMessage.sender.avatarUrl;
    res.send({ hostAppDataAction: { chatDataAction: { createMessageAction: { message: {
        text: 'Here\'s your avatar',
        cardsV2: [{
            cardId: 'avatarCard',
            card: {
                name: 'Avatar Card',
                header: {
                    title: `Hello ${displayName}!`,
                },
                sections: [{
                    widgets: [{
                        textParagraph: { text: 'Your avatar picture: ' }
                    }, {
                        image: { imageUrl: avatarUrl }
                    }]
                }]
            }
        }]
    }}}}});
};

Click Deploy.

Python

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.
Click Create Function.
On the Create function page, set up your function:
1. In Environment, select Cloud Run Function.
2. In Function name, enter AddOnChatApp.
3. In Region, select a region.
4. Under Authentication, select Require authentication.
5. Click Next.
In Runtime, select the most recent version of Python.
In Source code, select Inline Editor.
In Entry point, delete the default text and enter avatar_app.

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

from typing import Any, Mapping

import flask
import functions_framework

@functions_framework.http
def avatar_app(req: flask.Request) -> Mapping[str, Any]:
    """Google Cloud Function that handles requests from Google Chat

    Args:
        flask.Request: the request

    Returns:
        Mapping[str, Any]: the response
    """
    if req.method == "GET":
        return "Hello! This function must be called from Google Chat."

    request_json = req.get_json(silent=True)

    # Stores the Google Chat event as a variable.
    chat_message = request_json["chat"]["messagePayload"]["message"]

    # Replies with the sender's avatar in a card.
    display_name = chat_message["sender"]["displayName"]
    avatar_url = chat_message["sender"]["avatarUrl"]
    return { "hostAppDataAction": { "chatDataAction": { "createMessageAction": { "message": {
        "text": "Here's your avatar",
        "cardsV2": [{
            "cardId": "avatarCard",
            "card": {
                "name": "Avatar Card",
                "header": { "title": f"Hello {display_name}!" },
                "sections": [{
                    "widgets": [{
                        "textParagraph": { "text": "Your avatar picture:" }
                    }, {
                        "image": { "imageUrl": avatar_url }
                    }]
                }]
            }
        }]
    }}}}}

Click Deploy.

Java

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.
Click Create Function.
On the Create function page, set up your function:
1. In Environment, select Cloud Run Function.
2. In Function name, enter AddOnChatApp.
3. In Region, select a region.
4. Under Authentication, select Require authentication.
5. Click Next.
In Runtime, select the most recent version of Java.
In Source code, select Inline Editor.
In Entry point, delete the default text and enter AvatarApp.
Rename the default Java file to src/main/java/AvatarApp.java.

Replace the contents of AvatarApp.java with the following code:

import java.util.List;

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;

public class AvatarApp 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("chat")) {
            response.getWriter().write("Hello! This function is meant to be used " +
                "in a Google Chat Space..");
            return;
        }

        // Stores the Google Chat event as a variable.
        JsonObject chatMessage = body.getAsJsonObject("chat")
            .getAsJsonObject("messagePayload").getAsJsonObject("message");

        // Replies with the sender's avatar in a card.
        String displayName = chatMessage.getAsJsonObject("sender").get("displayName").getAsString();
        String avatarUrl = chatMessage.getAsJsonObject("sender").get("avatarUrl").getAsString();
        Message message = createMessage(displayName, avatarUrl);

        JsonObject createMessageAction = new JsonObject();
        createMessageAction.add("message", gson.fromJson(gson.toJson(message), JsonObject.class));

        JsonObject chatDataAction = new JsonObject();
        chatDataAction.add("createMessageAction", createMessageAction);

        JsonObject hostAppDataAction = new JsonObject();
        hostAppDataAction.add("chatDataAction", chatDataAction);

        JsonObject dataActions = new JsonObject();
        dataActions.add("hostAppDataAction", hostAppDataAction);
        response.getWriter().write(gson.toJson(dataActions));
    }

    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("avatarCard");
        cardWithId.setCard(card);

        Message message = new Message();
        message.setText("Here's your avatar");
        message.setCardsV2(List.of(cardWithId));

        return message;
    }
}

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

<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>avatar-app</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.target>17</maven.compiler.target>
        <maven.compiler.source>17</maven.compiler.source>
    </properties>

    <dependencies>
        <dependency>
        <groupId>com.google.cloud.functions</groupId>
        <artifactId>functions-framework-api</artifactId>
        <version>1.0.4</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 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>

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.

Authorize Google Chat to invoke your function

To Authorize Google Workspace add-on to invoke your function, add the Google Workspace add-on service account with the Cloud Run Invoker role.

In the Google Cloud console, go to the Cloud Run page:

Go to Cloud Run
In the Cloud Run services list, select the checkbox next to the receiving function. (Don't click the function itself.)
Click Permissions. The Permissions panel opens.
Click Add principal.
In New principals, enter the email address of the Google Workspace add-on service account associated to your project.
In Select a role, select Cloud Run > Cloud Run Invoker.
Click Save.

Configure the add-on

After the Cloud Function is deployed, follow these steps to create a add-on and deploy the Google Chat app:

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.
In the list of functions, click AddOnChatApp.
Click the Triggers tab.
Under HTTPS, copy the URL.
Search for "Google Chat API" and click Google Chat API, then click Manage.

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

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

Test your Chat app

To test your Chat app, open a direct message space with the Chat app and send a message:

Open Google Chat using the Google Workspace account that you provided when you added yourself as a trusted tester.

Go to Google Chat
Click New chat.
In the Add 1 or more people field, type the name of your Chat app.
Select your Chat app from the results. A direct message opens.

Note: If you don't see your Chat app in the list of results, ensure that you've included your Google Workspace account in the Visibility settings of the Chat API Configuration page in the Google Cloud console.
In the new direct message with the app, type Hello and press enter.

The Chat app's message contains a card 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

When a Google Chat app or card returns an error, the Chat interface surfaces a message saying "Something went wrong." or "Unable to process your request." Sometimes the Chat UI doesn't display any error message, but the Chat app or card produces an unexpected result; for example, a card message might not appear.

Although an error message might not display in the Chat UI, descriptive error messages and log data are available to help you fix errors when error logging for Chat apps is turned on. For help viewing, debugging, and fixing errors, see Troubleshoot and fix Google Chat errors.

Clean up

To avoid incurring charges to your Google Cloud account for the resources used in this tutorial, we recommend that you delete the Cloud project.

In the Google Cloud console, go to the Manage resources page. Click Menu > IAM & Admin > Manage Resources.
Go to Resource Manager
In the project list, select the project you want to delete and then click Delete .
In the dialog, type the project ID and then click Shut down to delete the project.