lambda_function.py

import os
import sys
from linebot import (
	LineBotApi, WebhookHandler
)
from linebot.models import (
	MessageEvent, TextMessage, TextSendMessage
)
from linebot.exceptions import (
	LineBotApiError, InvalidSignatureError
)
import logging

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

channel_secret = os.getenv('LINE_CHANNEL_SECRET', None)
channel_access_token = os.getenv('LINE_CHANNEL_ACCESS_TOKEN', None)
if channel_secret is None:
	logger.error('Specify LINE_CHANNEL_SECRET as environment variable.')
	sys.exit(1)
if channel_access_token is None:
	logger.error('Specify LINE_CHANNEL_ACCESS_TOKEN as environment variable.')
	sys.exit(1)

line_bot_api = LineBotApi(channel_access_token)
handler = WebhookHandler(channel_secret)

def lambda_handler(event, context):
	signature = event["headers"]["X-Line-Signature"]
	body = event["body"]
	ok_json = {"isBase64Encoded": False,
				"statusCode": 200,
				"headers": {},
				"body": ""}
	error_json = {"isBase64Encoded": False,
					"statusCode": 403,
					"headers": {},
					"body": "Error"}

	@handler.add(MessageEvent, message=TextMessage)
	def message(line_event):
		text = line_event.message.text
		line_bot_api.reply_message(line_event.reply_token, TextSendMessage(text=text))
	
	try:
		handler.handle(body, signature)
	except LineBotApiError as e:
		logger.error("Got exception from LINE Messaging API: %s\n" % e.message)
		for m in e.error.details:
			logger.error(" %s: %s " % (m.property, m.message))
		return error_json
	except InvalidSignatureError:
		return error_jason
	
	return ok_json