Add handler support for SNS, dynamodb and kinesis events

[parroyo]

Related to #225

I added a fix to process SNS, kinesis and DynamoDB AWS events. Sadly, I couldn't find a generic way to handle all the events like the s3 events.

The function to call in the handler is not send in other events but s3 ones. So I've added a AWS_EVENT_MAPPING property to zappa_settings.py in order to resolve the function to invoke based on the event source arn.

[coveralls]

Coverage increased (+1.1%) to 81.564% when pulling 27b7526 on parroyo:master into dbffbee on Miserlou:master.

[Miserlou]

@parroyo - sorry for not commenting on this earlier!

Mapping events to functions is what I was afraid of, but you've solved it with with AWS_EVENT_MAPPING, which looks to be an inspired solution. Thank you for including the tests as well!

[Miserlou]

Ah. I think there could be a problem with this, however.

This seems like it only coverts event sources, and not event types. For example, if I want to have a different function execute in response to SQS pushes and SQS pops on the same queue, this setting won't work. AWS_EVENT_MAPPING must need to be a dict of dicts?

[parroyo]

@Miserlou As far as I know, the only lambda subscription that supports different event types is the S3 one. And for S3 events, we are getting the function name to invoke based on the configurationId property, so you can have different functions to handle different events from the same S3 source

        if 's3' in record:
             return record['s3']['configurationId']

About the SQS events, they cannot invoke lambda functions. You can only subscribe to a SNS topic instead.

[Miserlou]

Ah, I see. Okay, gotcha. I'm going to think about this some more, but I think that we're all set then.

I really appreciate you taking the initiative on this issue, truly excellent work!