Two Slack App Installation Flow Example (Flask + SQLAlchemy)

app.py

import logging
from typing import Callable

logging.basicConfig(level=logging.DEBUG)
logging.getLogger("sqlalchemy.engine").setLevel(logging.INFO)

import os
from slack_bolt import App, BoltContext, Ack
from slack_bolt.adapter.flask import SlackRequestHandler
from slack_bolt.oauth.oauth_settings import OAuthSettings
from slack_sdk import WebClient
from slack_sdk.oauth.installation_store.sqlalchemy import SQLAlchemyInstallationStore
from slack_sdk.oauth.state_store.sqlalchemy import SQLAlchemyOAuthStateStore

import sqlalchemy
from sqlalchemy.engine import Engine

# TODO: change this domain
your_app_domain = "your-own-subdomain.ngrok.io"

logger = logging.getLogger(__name__)
client_id, client_secret, signing_secret = (
    os.environ["SLACK_CLIENT_ID"],
    os.environ["SLACK_CLIENT_SECRET"],
    os.environ["SLACK_SIGNING_SECRET"],
)

#
# Database
#
database_url = "sqlite:///slackapp.db"
engine: Engine = sqlalchemy.create_engine(database_url)
installation_store = SQLAlchemyInstallationStore(
    client_id=client_id,
    engine=engine,
    logger=logger,
)
oauth_state_store = SQLAlchemyOAuthStateStore(
    expiration_seconds=120,
    engine=engine,
    logger=logger,
)

# additional permissions associated with individual users
user_installation_store = SQLAlchemyInstallationStore(
    client_id=client_id,
    engine=engine,
    bots_table_name="user_slack_bots",  # just for compatibility with the built-in implementation - we won't use this
    installations_table_name="user_slack_installations",
    logger=logger,
)

# initialize database tables
try:
    engine.execute("select count(*) from slack_bots")
except Exception as e:
    installation_store.metadata.create_all(engine)
    oauth_state_store.metadata.create_all(engine)
    user_installation_store.metadata.create_all(engine)

#
# Main app
#

app = App(
    logger=logger,
    signing_secret=signing_secret,
    oauth_settings=OAuthSettings(
        client_id=client_id,
        client_secret=client_secret,
        installation_store=installation_store,
        state_store=oauth_state_store,
        scopes=["commands"],
        user_scopes=[],
    ),
)


@app.middleware
def set_user_token_if_exists(context: BoltContext, next: Callable):
    installation = user_installation_store.find_installation(
        enterprise_id=context.enterprise_id,
        team_id=context.team_id,
        user_id=context.user_id,
        is_enterprise_install=context.is_enterprise_install,
    )
    if installation is not None:
        context["user_token"] = installation.user_token
    next()


@app.command("/start-reacting")
def handle_commands(ack: Ack, body: dict, context: BoltContext, client: WebClient):
    if context.user_token is None:
        ack(
            text="Please grant this app to add reactions on behalf of you!",
            blocks=[
                {
                    "type": "section",
                    "text": {
                        "type": "mrkdwn",
                        "text": "Please grant this app to add reactions on behalf of you!",
                    },
                    "accessory": {
                        "type": "button",
                        "action_id": "link-button-click",
                        "text": {"type": "plain_text", "text": "Connect with this app"},
                        "value": "user_install",
                        "style": "primary",
                        "url": f"https://{your_app_domain}/slack/user_install",
                    },
                }
            ],
        )
        return

    ack()

    client.views_open(
        trigger_id=body["trigger_id"],
        view={
            "type": "modal",
            "title": {"type": "plain_text", "text": "My App"},
            "submit": {"type": "plain_text", "text": "Submit"},
            "close": {"type": "plain_text", "text": "Cancel"},
            "blocks": [
                {
                    "type": "section",
                    "text": {"type": "mrkdwn", "text": "Let's start!"},
                }
            ],
        },
    )


@app.action("link-button-click")
def handle_link_button_clicks(ack: Ack):
    ack()


# TODO: delete database rows when receiving tokens_revoked / app_uninstalled events

#
# Web App
#


from flask import Flask, request

flask_app = Flask(__name__)
handler = SlackRequestHandler(app)


@flask_app.route("/slack/events", methods=["POST"])
def slack_events():
    return handler.handle(request)


@flask_app.route("/slack/install", methods=["GET"])
def install():
    return handler.handle(request)


@flask_app.route("/slack/oauth_redirect", methods=["GET"])
def oauth_redirect():
    return handler.handle(request)


user_installation_app = App(
    logger=logger,
    signing_secret=signing_secret,
    oauth_settings=OAuthSettings(
        client_id=client_id,
        client_secret=client_secret,
        installation_store=user_installation_store,
        state_store=oauth_state_store,
        install_path="/slack/user_install",
        redirect_uri_path="/slack/user_oauth_redirect",
        redirect_uri=f"https://{your_app_domain}/slack/user_oauth_redirect",
        scopes=[],
        user_scopes=["reactions:write"],
    ),
)

user_handler = SlackRequestHandler(user_installation_app)


@flask_app.route("/slack/user_install", methods=["GET"])
def user_install():
    return user_handler.handle(request)


@flask_app.route("/slack/user_oauth_redirect", methods=["GET"])
def user_oauth_redirect():
    return user_handler.handle(request)


# pip install -r requirements.txt

# # -- OAuth flow -- #
# export SLACK_SIGNING_SECRET=***
# export SLACK_CLIENT_ID=111.111
# export SLACK_CLIENT_SECRET=***

# FLASK_APP=app.py FLASK_ENV=development flask run -p 3000

requirements.txt

slack-bolt>=1.4.3,<2
Flask>=1.1,<2
SQLAlchemy