Develop a Slack Bot Plugin

What You’ll Learn:

Gain a solid understanding of how to build a Slack Bot that’s powered by AI—one that can respond to user questions right inside Slack.

Project Background

The Dify plugin ecosystem focuses on making integrations simpler and more accessible. In this guide, we’ll use Slack as an example, walking you through the process of developing a Slack Bot plugin. This allows your team to chat directly with an LLM within Slack, significantly improving how efficiently they can use AI.

Slack is an open, real-time communication platform with a robust API. Among its features is a webhook-based event system, which is quite straightforward to develop on. We’ll leverage this system to create a Slack Bot plugin, illustrated in the diagram below:

To avoid confusion, the following concepts are explained:
Slack Bot A chatbot on the Slack platform, acting as a virtual user you can interact with in real-time.
Slack Bot Plugin A plugin in the Dify Marketplace that connects a Dify application with Slack. This guide focuses on how to develop that plugin.

How It Works (A Simple Overview):

Send a Message to the Slack Bot
When a user in Slack sends a message to the Bot, the Slack Bot immediately issues a webhook request to the Dify platform.
Forward the Message to the Slack Bot Plugin
The Dify platform triggers the Slack Bot plugin, which relays the details to the Dify application—similar to entering a recipient’s address in an email system. By setting up a Slack webhook address through Slack’s API and entering it in the Slack Bot plugin, you establish this connection. The plugin then processes the Slack request and sends it on to the Dify application, where the LLM analyzes the user’s input and generates a response.
Return the Response to Slack

Once the Slack Bot plugin receives the reply from the Dify application, it sends the LLM’s answer back through the same route to the Slack Bot. Users in Slack then see a more intelligent, interactive experience right where they’re chatting.

Prerequisites

Dify plugin developing tool: For more information, see Initializing the Development Tool.
Python environment (version ≥ 3.12): Refer to this Python Installation Tutorial or ask an LLM for a complete setup guide.
Create a Slack App and Get an OAuth Token

Go to the Slack API platform, create a Slack app from scratch, and pick the workspace where it will be deployed.

Enable Webhooks:

Install the App in Your Slack Workspace:

Obtain an OAuth Token for future plugin development:

1. Developing the Plugin

Now we’ll dive into the actual coding. Before starting, make sure you’ve read Quick Start: Developing an Extension Plugin or have already built a Dify plugin before.

1.1 Initialize the Project

Run the following command to set up your plugin development environment:

dify plugin init

Follow the prompts to provide basic project info. Select the extension template, and grant both Apps and Endpoints permissions.

For additional details on reverse-invoking Dify services within a plugin, see Reverse Invocation: App.

1.2 Edit the Configuration Form

This plugin needs to know which Dify app should handle the replies, as well as the Slack App token to authenticate the bot’s responses. Therefore, you’ll add these two fields to the plugin’s form.

Modify the YAML file in the group directory—for example, group/slack.yaml. The form’s filename is determined by the info you provided when creating the plugin, so adjust it accordingly.

Sample Code:

slack.yaml

settings:
  - name: bot_token
    type: secret-input
    required: true
    label:
      en_US: Bot Token
      zh_Hans: Bot Token
      pt_BR: Token do Bot
      ja_JP: Bot Token
    placeholder:
      en_US: Please input your Bot Token
      zh_Hans: 请输入你的 Bot Token
      pt_BR: Por favor, insira seu Token do Bot
      ja_JP: ボットトークンを入力してください
  - name: allow_retry
    type: boolean
    required: false
    label:
      en_US: Allow Retry
      zh_Hans: 允许重试
      pt_BR: Permitir Retentativas
      ja_JP: 再試行を許可
    default: false
  - name: app
    type: app-selector
    required: true
    label:
      en_US: App
      zh_Hans: 应用
      pt_BR: App
      ja_JP: アプリ
    placeholder:
      en_US: the app you want to use to answer Slack messages
      zh_Hans: 你想要用来回答 Slack 消息的应用
      pt_BR: o app que você deseja usar para responder mensagens do Slack
      ja_JP: あなたが Slack メッセージに回答するために使用するアプリ
endpoints:
  - endpoints/slack.yaml

Explanation of the Configuration Fields:

  - name: app
    type: app-selector
    scope: chat

type: Set to app-selector, which allows users to forward messages to a specific Dify app when using this plugin.
scope: Set to chat, meaning the plugin can only interact with app types such as agent, chatbot, or chatflow.

Finally, in the endpoints/slack.yaml file, change the request method to POST to handle incoming Slack messages properly.

Sample Code:

endpoints/slack.yaml

path: "/"
method: "POST"
extra:
  python:
    source: "endpoints/slack.py"

2. Edit the function code

Modify the endpoints/slack.py file and add the following code:

import json
import traceback
from typing import Mapping
from werkzeug import Request, Response
from dify_plugin import Endpoint
from slack_sdk import WebClient
from slack_sdk.errors import SlackApiError


class SlackEndpoint(Endpoint):
    def _invoke(self, r: Request, values: Mapping, settings: Mapping) -> Response:
        """
        Invokes the endpoint with the given request.
        """
        retry_num = r.headers.get("X-Slack-Retry-Num")
        if (not settings.get("allow_retry") and (r.headers.get("X-Slack-Retry-Reason") == "http_timeout" or ((retry_num is not None and int(retry_num) > 0)))):
            return Response(status=200, response="ok")
        data = r.get_json()

        # Handle Slack URL verification challenge
        if data.get("type") == "url_verification":
            return Response(
                response=json.dumps({"challenge": data.get("challenge")}),
                status=200,
                content_type="application/json"
            )
        
        if (data.get("type") == "event_callback"):
            event = data.get("event")
            if (event.get("type") == "app_mention"):
                message = event.get("text", "")
                if message.startswith("<@"):
                    message = message.split("> ", 1)[1] if "> " in message else message
                    channel = event.get("channel", "")
                    blocks = event.get("blocks", [])
                    blocks[0]["elements"][0]["elements"] = blocks[0].get("elements")[0].get("elements")[1:]
                    token = settings.get("bot_token")
                    client = WebClient(token=token)
                    try: 
                        response = self.session.app.chat.invoke(
                            app_id=settings["app"]["app_id"],
                            query=message,
                            inputs={},
                            response_mode="blocking",
                        )
                        try:
                            blocks[0]["elements"][0]["elements"][0]["text"] = response.get("answer")
                            result = client.chat_postMessage(
                                channel=channel,
                                text=response.get("answer"),
                                blocks=blocks
                            )
                            return Response(
                                status=200,
                                response=json.dumps(result),
                                content_type="application/json"
                            )
                        except SlackApiError as e:
                            raise e
                    except Exception as e:
                        err = traceback.format_exc()
                        return Response(
                            status=200,
                            response="Sorry, I'm having trouble processing your request. Please try again later." + str(err),
                            content_type="text/plain",
                        )
                else:
                    return Response(status=200, response="ok")
            else:
                return Response(status=200, response="ok")
        else:
            return Response(status=200, response="ok")

2. Debugging Plugins

### 2. Debug the Plugin

Go to the Dify platform and obtain the remote debugging address and key for your plugin.

<figure><img src="https://assets-docs.dify.ai/2025/01/8d24006f0cabf5bf61640a9023c45db8.png" alt=""><figcaption></figcaption></figure>

Back in your plugin project, copy the `.env.example` file and rename it to `.env`.

```bash
INSTALL_METHOD=remote
REMOTE_INSTALL_HOST=remote-url
REMOTE_INSTALL_PORT=5003
REMOTE_INSTALL_KEY=****-****-****-****-****

Run python -m main to start the plugin. You should now see your plugin installed in the Workspace on Dify’s plugin management page. Other team members will also be able to access it.

python -m main

Configure the Plugin Endpoint

From the plugin management page in Dify, locate the newly installed test plugin and create a new endpoint. Provide a name, a Bot token, and select the app you want to connect.

After saving, a POST request URL is generated:

Next, complete the Slack App setup:

3. Verify the Plugin

In your code, self.session.app.chat.invoke is used to call the Dify application, passing in parameters such as app_id and query. The response is then returned to the Slack Bot. Run python -m main again to restart your plugin for debugging, and check whether Slack correctly displays the Dify App’s reply:

4. Package the Plugin (Optional)

Once you confirm that the plugin works correctly, you can package and name it via the following command. After it runs, you’ll find a slack_bot.difypkg file in the current directory—your final plugin package.

dify plugin package ./slack_bot

Congratulations! You’ve successfully developed, tested, and packaged a plugin!

5. Publish the Plugin (Optional)

You can now upload it to the Dify Marketplace repository for public release. Before publishing, ensure your plugin meets the Plugin Publishing Guidelines. Once approved, your code is merged into the main branch, and the plugin goes live on the Dify Marketplace.