According to the documentation and experience of many people, lambda is executed at least once: http://docs.aws.amazon.com/lambda/latest/dg/API_Invoke.html
This is quite an issue if you have endpoints mutating the data. Is there anything in the serverless framework to prevent that? Making every endpoint idempotent on the application level would be quite a big hassle.
Did anybody ever face issue related to having lambda triggered multiple times in response to a single api call?