End of support notice: On May 20, 2026, AWS will end support for AWS IoT Events. After May 20, 2026, you will no longer be able to access the AWS IoT Events console or AWS IoT Events resources. For more information, see [AWS IoT Events end of support](https://docs.aws.amazon.com/iotevents/latest/developerguide/iotevents-end-of-support.html).

# Creating a custom Lambda function for AWS IoT Events
<a name="alarms-create-custom-lambda"></a>

You can create a Lambda function or modify the one provided by AWS IoT Events.

The following requirements apply when you create a custom Lambda function.
+ Add permissions that allow your Lambda function to perform specified actions and access AWS resources.
+ If you use the Lambda function provided by AWS IoT Events, make sure that you choose the Python 3.7 runtime.

Example Lambda function:

```
import boto3
import json
import logging
import datetime
logger = logging.getLogger()
logger.setLevel(logging.INFO)
ses = boto3.client('ses')
sns = boto3.client('sns')
def check_value(target):
  if target:
    return True
  return False

# Check whether email is verified. Only verified emails are allowed to send emails to or from.
def check_email(email):
  if not check_value(email):
    return False
  result = ses.get_identity_verification_attributes(Identities=[email])
  attr = result['VerificationAttributes']
  if (email not in attr or attr[email]['VerificationStatus'] != 'Success'):
      logging.info('Verification email for {} sent. You must have all the emails verified before sending email.'.format(email))
      ses.verify_email_identity(EmailAddress=email)
      return False
  return True

# Check whether the phone holder has opted out of receiving SMS messages from your account
def check_phone_number(phone_number):
  try:
    result = sns.check_if_phone_number_is_opted_out(phoneNumber=phone_number)
    if (result['isOptedOut']):
        logger.info('phoneNumber {} is not opt in of receiving SMS messages. Phone number must be opt in first.'.format(phone_number))
        return False
    return True
  except Exception as e:
    logging.error('Your phone number {} must be in E.164 format in SSO. Exception thrown: {}'.format(phone_number, e))
    return False

def check_emails(emails):
  result = True
  for email in emails:
      if not check_email(email):
          result = False
  return result

def lambda_handler(event, context):
  logging.info('Received event: ' + json.dumps(event))
  nep = json.loads(event.get('notificationEventPayload'))
  alarm_state = nep['alarmState']
  default_msg = 'Alarm ' + alarm_state['stateName'] + '\n'
  timestamp = datetime.datetime.utcfromtimestamp(float(nep['stateUpdateTime'])/1000).strftime('%Y-%m-%d %H:%M:%S')
  alarm_msg = "{} {} {} at {} UTC ".format(nep['alarmModelName'], nep.get('keyValue', 'Singleton'), alarm_state['stateName'], timestamp)
  default_msg += 'Sev: ' + str(nep['severity']) + '\n'
  if (alarm_state['ruleEvaluation']):
    property = alarm_state['ruleEvaluation']['simpleRule']['inputProperty']
    default_msg += 'Current Value: ' + str(property) + '\n'
    operator = alarm_state['ruleEvaluation']['simpleRule']['operator']
    threshold = alarm_state['ruleEvaluation']['simpleRule']['threshold']
    alarm_msg += '({} {} {})'.format(str(property), operator, str(threshold))
  default_msg += alarm_msg + '\n'

  emails = event.get('emailConfigurations', [])
  logger.info('Start Sending Emails')
  for email in emails:
    from_adr = email.get('from')
    to_adrs = email.get('to', [])
    cc_adrs = email.get('cc', [])
    bcc_adrs = email.get('bcc', [])
    msg = default_msg + '\n' + email.get('additionalMessage', '')
    subject = email.get('subject', alarm_msg)
    fa_ver = check_email(from_adr)
    tas_ver = check_emails(to_adrs)
    ccas_ver = check_emails(cc_adrs)
    bccas_ver = check_emails(bcc_adrs)
    if (fa_ver and tas_ver and ccas_ver and bccas_ver):
      ses.send_email(Source=from_adr,
                     Destination={'ToAddresses': to_adrs, 'CcAddresses': cc_adrs, 'BccAddresses': bcc_adrs},
                     Message={'Subject': {'Data': subject}, 'Body': {'Text': {'Data': msg}}})
      logger.info('Emails have been sent')

  logger.info('Start Sending SNS message to SMS')
  sns_configs = event.get('smsConfigurations', [])
  for sns_config in sns_configs:
    sns_msg = default_msg + '\n' + sns_config.get('additionalMessage', '')
    phone_numbers = sns_config.get('phoneNumbers', [])
    sender_id = sns_config.get('senderId')
    for phone_number in phone_numbers:
        if check_phone_number(phone_number):
          if check_value(sender_id):
            sns.publish(PhoneNumber=phone_number, Message=sns_msg, MessageAttributes={'AWS.SNS.SMS.SenderID':{'DataType': 'String','StringValue': sender_id}})
          else:
            sns.publish(PhoneNumber=phone_number, Message=sns_msg)
          logger.info('SNS messages have been sent')
```