Slack Bolt for Python

Warnings

• breaking Python 3.6 support has been officially dropped. Applications running on Python 3.6 will need to upgrade to Python 3.7 or newer.
  Fix: Upgrade your Python environment to 3.7 or later. The `requires_python` metadata is `^3.7`.
• gotcha Deployment strategies differ significantly for local development versus production. `App.start()` or `SocketModeHandler` is for local Socket Mode development. For production, you must use an HTTP adapter (e.g., `FlaskResponder`, `AwsLambdaPythonReceiver`) and expose an endpoint for Slack to send events.
  Fix: For production, use `AsyncApp` with an appropriate HTTP adapter (e.g., `from slack_bolt.adapter.flask import FlaskResponder`) and deploy to a web server capable of handling HTTP requests from Slack. Consult the official Bolt documentation on deployment.
• gotcha All Slack apps require careful configuration within api.slack.com/apps, including setting correct OAuth Scopes, enabling Event Subscriptions, and verifying the Slack Signing Secret. Many errors (e.g., 401 Unauthorized, events not being received) stem from misconfigurations or missing environment variables.
  Fix: Double-check your Slack App's Basic Information, OAuth & Permissions, Event Subscriptions, and Interactivity & Shortcuts settings on api.slack.com/apps. Ensure `SLACK_BOT_TOKEN`, `SLACK_SIGNING_SECRET`, and `SLACK_APP_TOKEN` (for Socket Mode) are correctly set in your application's environment variables.
• gotcha New AI-enabled features like `say_stream` and `set_status` (for streaming messages and showing loading states) introduced in v1.26.0 and v1.28.0 require specific Bolt versions and may depend on the latest Slack platform features. If these methods are not available or behave unexpectedly, check your Bolt version and Slack app setup.
  Fix: Upgrade `slack-bolt` to the latest version (e.g., `pip install --upgrade slack-bolt`). Ensure your Slack App has the necessary permissions and features enabled on the Slack API dashboard, especially if using beta or experimental AI capabilities.

Install

• pip install slack-bolt Install Bolt

Imports

• App

  from slack_bolt import App

• AsyncApp

  from slack_bolt.async_app import AsyncApp

  Use AsyncApp for asynchronous operations and improved performance, especially with ASGI servers.
• SocketModeHandler

  from slack_bolt.adapter.socket_mode import SocketModeHandler

  Required for local development and connecting to Slack via WebSockets.
• FlaskResponder

  from slack_bolt.adapter.flask import FlaskResponder

  One of several HTTP adapters for deploying Bolt apps to web servers.

Quickstart

This quickstart demonstrates a minimal Slack Bolt app that responds to 'hello' messages in a channel. It uses Socket Mode for local development, requiring `SLACK_BOT_TOKEN`, `SLACK_SIGNING_SECRET`, and `SLACK_APP_TOKEN` environment variables. For production deployments, an HTTP adapter like Flask, Django, or AWS Lambda is typically used.

import os
from slack_bolt import App
from slack_bolt.adapter.socket_mode import SocketModeHandler

# Initialize your app with your bot token and signing secret
# Ensure SLACK_BOT_TOKEN, SLACK_SIGNING_SECRET, and SLACK_APP_TOKEN are set in your environment
app = App(
    token=os.environ.get("SLACK_BOT_TOKEN", ""),
    signing_secret=os.environ.get("SLACK_SIGNING_SECRET", "")
)

# Listen for messages containing "hello"
@app.message("hello")
def message_hello(message, say):
    # say() sends a message to the same channel where the event was triggered
    say(f"Hey there <@{message['user']}>!")

# Start your app
# For local development, Socket Mode is often used.
# For production, you'd typically use an HTTP adapter (e.g., Flask, AWS Lambda).
if __name__ == "__main__":
    # SLACK_APP_TOKEN is required for Socket Mode
    SocketModeHandler(app, os.environ.get("SLACK_APP_TOKEN", "")).start()