def handler(event, context) -> None:
"""
Handles incoming event.
:param event: Invocation event.
:param context: Invocation context.
:return: No return.
"""
response = CfnResponse(event, context)
try:
data, resource_id = __handle(event, context)
response.respond(CfnResponse.CfnResponseStatus.SUCCESS,
data=data,
resource_id=resource_id)
except ClientError as ex:
err_msg = f'{repr(ex)}:{ex.response}'
response.respond(CfnResponse.CfnResponseStatus.FAILED,
status_reason=err_msg)
logger.exception(ex)
except Exception as ex:
response.respond(CfnResponse.CfnResponseStatus.FAILED,
status_reason=repr(ex))
logger.exception(ex)
def handler(event: Union[CreateEvent, UpdateEvent, DeleteEvent], context):
# Log the event to CloudWatch Logs for debugging (if needed)
# Using /r instead of /n makes the log entry nicely expandable in CloudWatch logs
print(json.dumps(event, indent=2).replace("\n", "\r"))
# The outer try-except block ensures that a response is ALWAYS send to CloudFormation
try:
# Use the "RequestType" from the event (Create/Update/Delete),
# to determine the right function to call, and then call it passing the event.
#
# Each handling function should return a tuple containing:
# - physical_resource_id (str): the physical resource id of your Custom Resource.
# This is an important field that you should specify explicitly.
# If you change the value of this field during a CloudFormation Update,
# CloudFormation will issue a Delete against the previous value.
# - response_data (dict): dictionary with key-value pairs that you can !GetAtt
# in your CloudFormation template
physical_resource_id, response_data = getattr(
Handlers, event["RequestType"])(event)
# All done! Let CloudFormation know about our success
CfnResponse.send(
event,
context,
CfnResponse.SUCCESS,
response_data=response_data,
physical_resource_id=physical_resource_id,
)
except Exception as e:
# Oops, we failed! Let's tell CloudFormation about this, so it knows
# and can rollback other changes in the stack
CfnResponse.send(
event,
context,
CfnResponse.FAILED,
str(e),
physical_resource_id=cast(Union[UpdateEvent, DeleteEvent],
event).get("PhysicalResourceId"),
)
# Do raise the error again after sending the CloudFormation response:
# - this makes the error (and stack) visible in CloudWatch Logs
# - this reflects the invocation failure in CloudWatch metrics
raise