Filling in the chapter 4 alerts consumer

sylvilagus/python/sylvilagus/ch04/alert_consumer.py

@@ -0,0 +1,100 @@
+from __future__ import print_function
+
+import json
+import smtplib
+import sys
+
+import pika
+
+
+AMQP_SERVER = 'localhost'
+AMQP_USER = 'alert_user'
+AMQP_PASS = 'alertme'
+AMQP_VHOST = '/'
+AMQP_EXCHANGE = 'alerts'
+OPS_EMAILS = ['daniel.buch+sylvilagus-alerts-ops@gmail.com']
+ADMIN_EMAILS = ['daniel.buch+sylvilagus-alerts-admin@gmail.com']
+
+
+def main():
+    creds_broker = pika.PlainCredentials(AMQP_USER, AMQP_PASS)
+    conn_params = pika.ConnectionParameters(AMQP_SERVER,
+                                            virtual_host=AMQP_VHOST,
+                                            credentials=creds_broker)
+    conn_broker = pika.BlockingConnection(conn_params)
+
+    channel = conn_broker.channel()
+
+    channel.exchange_declare(exchange=AMQP_EXCHANGE,
+                             exchange_type='topic',
+                             auto_delete=False)
+    channel.queue_declare(queue='critical', auto_delete=False)
+    channel.queue_bind(queue='critical',
+                       exchange='alerts',
+                       routing_key='critical.*')
+    channel.queue_declare(queue='rate_limit', auto_delete=False)
+    channel.queue_bind(queue='rate_limit',
+                       exchange='alerts',
+                       routing_key='*.rate_limit')
+
+    channel.basic_consume(critical_notify,
+                          queue='critical',
+                          no_ack=False,
+                          consumer_tag='critical')
+    channel.basic_consume(rate_limit_notify,
+                          queue='rate_limit',
+                          no_ack=False,
+                          consumer_tag='rate_limit')
+
+    try:
+        print('Ready for alerts!')
+        channel.start_consuming()
+    except KeyboardInterrupt:
+        conn_broker.close()
+        return 0
+
+
+def send_mail(recipients, subject, message):
+    """Email generator for received alerts."""
+    headers = '\r\n'.join([
+        'From: alerts@sylvilagus.local',
+        'To: ',
+        'Date: ',
+        'Subject: {}'.format(subject)
+    ]) + '\r\n'
+    smtp_server = smtplib.SMTP()
+    smtp_server.connect('localhost', 25)
+    smtp_server.sendmail('alerts@sylvilagus.local',
+                         recipients,
+                         headers + str(message))
+    smtp_server.close()
+
+
+def critical_notify(channel, method, header, body):
+    """Sends CRITICAL alerts to administrators via email."""
+    message = json.loads(body)
+
+    send_mail(OPS_EMAILS, 'CRITICAL ALERT', message)
+    print('Sent alert via email! Alert Text: {} \nRecipients: {}'.format(
+            message, OPS_EMAILS
+        )
+    )
+
+    channel.basic_ack(delivery_tag=method.delivery_tag)
+
+
+def rate_limit_notify(channel, method, header, body):
+    """Sends the message to the administrators via email."""
+    message = json.loads(body)
+
+    send_mail(ADMIN_EMAILS, 'RATE LIMIT ALERT!', message)
+    print('Sent alert via email! Alert Text: {} \nRecipients: {}'.format(
+            message, ADMIN_EMAILS
+        )
+    )
+
+    channel.basic_ack(delivery_tag=method.delivery_tag)
+
+
+if __name__ == '__main__':
+    sys.exit(main())