afterhours-shift-manager/src/handler.py

"""Lambda handler — Slack Bolt app entry point."""

import logging
import os

import boto3
from slack_bolt.adapter.aws_lambda import SlackRequestHandler

from src.app import create_app

logger = logging.getLogger()
logger.setLevel(logging.INFO)

SlackRequestHandler.clear_all_log_handlers()
logging.basicConfig(format="%(asctime)s %(levelname)s %(name)s: %(message)s", level=logging.INFO)

# Lazy-initialized app singleton
_slack_handler = None


def _get_handler() -> SlackRequestHandler:
    global _slack_handler
    if _slack_handler is None:
        ssm = boto3.client("ssm")
        bot_token = ssm.get_parameter(
            Name=os.environ["SLACK_BOT_TOKEN_PARAM"], WithDecryption=True
        )["Parameter"]["Value"]
        signing_secret = ssm.get_parameter(
            Name=os.environ["SLACK_SIGNING_SECRET_PARAM"], WithDecryption=True
        )["Parameter"]["Value"]
        schedule_channel = ssm.get_parameter(
            Name=os.environ["SHIFT_CHANNEL_PARAM"], WithDecryption=True
        )["Parameter"]["Value"]

        app = create_app(bot_token, signing_secret, schedule_channel=schedule_channel)
        _slack_handler = SlackRequestHandler(app=app)
    return _slack_handler


def handler(event, context):
    return _get_handler().handle(event, context)