Kubernetes: What's the idiomatic way in K8s to setup a custom proxy between ingress and its services?

So after a lot of reading and googling I found that the solution was to use API Gateways that are available as libraries (preferrably based on .Net):

Ocelot placed behind the nginx ingress fits the bill perfectly

Ocelot is a .NET API Gateway. This project is aimed at people using .NET running a micro services / service oriented architecture that need a unified point of entry into their system. However it will work with anything that speaks HTTP and run on any platform that ASP.NET Core supports.

Ocelot is currently used by Microsoft and Tencent.

The custom middleware and header/query/claims transformation solves my problem. Here are some worthy links

Microsoft Docs: Implement API Gateways with Ocelot

Ocelot on Github

Ocelot Documentation

Features

A quick list of Ocelot's capabilities for more information see the documentation.

• Routing

• Request Aggregation

• Service Discovery with Consul & Eureka

• Service Fabric

• Kubernetes

• WebSockets

• Authentication

• Authorisation

• Rate Limiting

• Caching

• Retry policies / QoS

• Load Balancing

• Logging / Tracing / Correlation

• Headers / Query String / Claims Transformation

• Custom Middleware / Delegating Handlers

• Configuration / Administration REST API

• Platform / Cloud Agnostic