I have defined this SNS-triggered Lambda in Chalice:
@app.on_sns_message(topic='arn:aws:sns:us-west-1:XXXXXXXX:MyTopic')
def step1_photo_url_preload(event, retry = 3):
try:
js = json.loads(event.message)
... some logic here, event object is never modified ...
except:
if retry:
print("WARNING: failed, %d retries remaining" % retry)
return step1_photo_url_preload(event, retry-1)
else:
raise
When an exception is raised, the function should retry up to 3 times.
Instead, what I get is the exception below. Look closely at the trace: Line 56 shows the error occurs when attempting the recursive call:
[ERROR] TypeError: 'SNSEvent' object is not subscriptable
Traceback (most recent call last):
File "/var/task/chalice/app.py", line 1459, in __call__
return self.func(event_obj)
File "/var/task/app.py", line 56, in step1_photo_url_preload
return step1_photo_url_preload(event, retry-1)
File "/var/task/chalice/app.py", line 1458, in __call__
event_obj = self.event_class(event, context)
File "/var/task/chalice/app.py", line 1486, in __init__
self._extract_attributes(event_dict)
File "/var/task/chalice/app.py", line 1532, in _extract_attributes
first_record = event_dict['Records'][0]
Mysteriously, the function can't work with the event object that it received the first time.
What could cause this?
I suspect this might have something to do with the magic behind @app.on_sns_message, but I'm not sure where to look next.
The problem is the fact that the function is decorated, the failure is in the code the decorator is running. Pull the functionality you want to run recursively into a separate function and the problem should go away.