Configurable HTTP payload size limit

[SimonSapin]

This is discussion for the experimental feature added in #3130

Configuration:

limits:
  http_max_request_bytes: 2000000 # Default value: 2 MB

When the Router receives a GraphQL request over HTTP, it will read no more than the configured size for the HTTP body. Very large requests take time to parse and process, and occupy space in RAM during that time. At the extreme, large requests can cause the process to run out of memory and are potential denial-of-service vectors.

We believe the limit should definitely exist. There is debate on whether it should be configurable.

If you do configure it, please tell us here about your use case and experience.

[SimonSapin]

This feature is now moving form experimental to general availability: #4442