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Last active May 2, 2019
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import os
import logging #for proper function logging
import boto3
import time
logger = logging.getLogger()
personal_email = os.environ['email_address']
topic_name = 'aws-iot-button-sns-topic-python'
client_sns = boto3.client('sns')
client_dynamo = boto3.client('dynamodb')
resource_dynamo = boto3.resource('dynamodb')
client_ec2 = boto3.client('ec2')
list_instances = []
def create_sns_topic():
# This function is idempotent no need to manually check if topic already exits
response = client_sns.create_topic(Name=topic_name)
return response
# This funtion is called to create_sns_subscription check
# if the subscription is on Pending confirmaion or accepted
def find_existing_subscription(topic_arn_iot):
response = client_sns.list_subscriptions_by_topic(
TopicArn= topic_arn_iot
return response
# Create SNS topic to email specified on the envrron
def create_sns_subscription(topic_arn_iot):
state_subscription = find_existing_subscription(topic_arn_iot) # Function to check if subscriptopn exists
# If handles if subscription already exits or not
if not state_subscription['Subscriptions']:
response = client_sns.subscribe(
TopicArn= topic_arn_iot,
Protocol= 'email',
Endpoint = personal_email
return response
result_subscription = state_subscription['Subscriptions'][0]['SubscriptionArn']
if result_subscription == 'PendingConfirmation':
response= client_sns.subscribe(
return response
return response
except Exception as err:
logger.error('Program could not set proper subscription {}'.format(err))
#Send email with informatio about the IoT button
def email_subscription(topic_arn_iot, event, item_table_count, delete_instances):
item_table_count = 2000 - item_table_count
Message="""{} -- processed by Python 3.6 Lambda
Battery voltage: {}
There are {} clicks left.
The following instances were deleted {}""".format(event['serialNumber'], event['batteryVoltage'], item_table_count, delete_instances),
Subject="Hello from your IoT Button {}: {}".format(event['serialNumber'], event['clickType'])
)'Message sent')
except Exception as err:
logger.error('Could not send email please topic {}'.format(err))
#Creates dynamo table
def create_dynamo_table(event):
iot_button_count = event['serialNumber']
#Checks if table exist if not creates table
response_query = client_dynamo.list_tables()
if iot_button_count not in response_query['TableNames']:
response = client_dynamo.create_table(
'AttributeName': 'count',
'AttributeType': 'S'
'AttributeName': 'count',
'KeyType': 'HASH'
'ReadCapacityUnits': 5,
'WriteCapacityUnits': 5
)"table created {}".format(response))
else:"table is already created {}".format(iot_button_count))
def create_item_dynamo(event):
iot_button_count = event['serialNumber']
unix_time = str(time.time())
TableName= iot_button_count,
Item= {
'count': {
'S': unix_time
response = resource_dynamo.Table(iot_button_count)
return response.scan()['ScannedCount']
def delete_ec2_intances():
response_ec2 = client_ec2.describe_instances()
if not response_ec2:
for reservation in response_ec2["Reservations"]:
for instance in reservation['Instances']:
list_instances.append(instance['InstanceId'])'intances to be deleted {}'.format(list_instances))
response = client_ec2.terminate_instances(
return list_instances
# Min point of entry to the function
def lambda_handler(event, context):'Starting Function')'The following payload was received')
# print infomation about the payload being passed
print('serial number {}'.format(event['serialNumber']))
print('batteryVoltage {}'.format(event['batteryVoltage']))
print('clickType {}'.format(event['clickType']))
print('email to be used {}'.format(personal_email))
#Calls function to create topic
topic_arn_iot = create_sns_topic()'Topic ARN is {}'.format(topic_arn_iot['TopicArn']))
#Calls function to create subscription
subscription = create_sns_subscription(topic_arn_iot['TopicArn'])
#Calls function to create dynamo_table
#Add events to dynamo table to keep track of click
item_table_count = create_item_dynamo(event)
#Delete any EC2 instances
delete_instances = delete_ec2_intances()
#Calls function to email data
email_subscription(topic_arn_iot['TopicArn'], event, item_table_count, delete_instances)
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