api.request.input and param filtering

Rails' filter_parameters system is used by e.g. Rails logging and error notification APIs like Airbrake to avoid sensitive information leaking out. It works by running over a hash and overwriting it for certain keys. However, Grape puts the entire request body in env['api.request.input'] as a string, which means the param filtering doesn't operate on it. This can lead to e.g. plaintext passwords getting logged in error catchers.

This can be solved by adding 'api.request.input' to filter_parameters in Rails application configuration. Should I adapt the documentation to warn people about this, or should we look for other ways to avoid this behaviour?

Start by reviewing Rails' filter_parameters handling and how Grape populates env['api.request.input']; no repository file or test is named. Resolve whether the intended outcome is a documentation warning or a code-level filtering change, then validate the chosen behavior against error logging and sensitive request data.