Lambda function that sends a daily E-mail with the title of the daily free eBook of Packt

packt_daily_book_notifier.py

import os
from datetime import datetime
from urllib.request import urlopen
import boto3
import re

CLAIM_PAGE = os.environ['claim_page']
SNS_TOPIC = os.environ['topic_arn']
EMAIL = os.environ['email']


def check_daily_book():
    '''Open the claim page for the daily free eBook and extract
    the title of the book. Then it by SNS to my email.
    '''
    with urlopen(CLAIM_PAGE) as stream:
        html = stream.read().decode("utf-8")
        print('Length of html: %d' % len(html))
        r = re.search(r'<div class="dotd-title">\s*?<h2>\s*(.+?)\s*</h2>\s*?</div>', html)
        if r:
            title = r.group(1).strip()
            print(title)
            
            sns = boto3.client('sns')
            subject = "Packt Daily: " + (title[:57] + '...' if len(title) > 60 else title)
            msg = ""
            msg += "Packt daily free eBook is '%s'" % title
            msg += "\r\n\r\n"
            msg += "Check it out at " + CLAIM_PAGE
            
            sns.publish(
                TopicArn=SNS_TOPIC,
                Message=msg,
                Subject=subject
                )
            return title
    return None

def lambda_handler(event, context):
    print('Checking {} at {}...'.format(CLAIM_PAGE, event['time']))
    try:
        check_daily_book()
    except:
        print('Check failed!')
        raise
    else:
        print('Check passed!')
        return event['time']
    finally:
        print('Check complete at {}'.format(str(datetime.now())))