How to write a validating proxy service for clients?

Question

Highload

There will be mobile and web clients that will make requests to the server infrastructure. Client requests will have the same basic structure for validation. In order to avoid validation of the client request on all services, it was proposed to write a separate service. It will validate the client, wrap the client request with its parameters and proxy further along the server infrastructure. It is interesting to hear opinions on the implementation of this task?

Answer 1

Nasxi/ModSecurity

Answer 2

what exactly is the difficulty?

----запрос---> сервис валидации <---- запрос валидный ----> бэкэнд
        ^                            |
        |                  запрос не валидный
        |                            |
        ----- 400 -----------