Pancake is a smart gRPC reverse proxy or API gateway, allowing many microservices to be exposed as a single server.
Pancake automatically discovers gRPC services on different upstream servers using the standard reflection service. When a gRPC request arrives at Pancake, it automatically forwards that request to an upstream server that implements the requested service. If multiple servers implement the same service, load balancing is performed as well.
This functionality makes configuration extremely easy and allows Pancake to basically work "out of the box". A minimal configuration could look something like this:
servers:
# Simply list all servers in your cluster
# Pancake will figure out how to route requests by itself
- address: localhost:5000
- address: localhost:5001Obviously, load balancing the Reflection and Health services would cause issues, but Pancake will also take care of that.
Pancake provides it's own reflection service, which will include all the services on the upstream servers. For example, if you have two servers, one implementing ServiceA, the other ServiceB, calling ListServices on Pancake will report ["ServiceA", "ServiceB", ...]
To clients it would look like they're talking to a single server, implementing both services.
Pancake translates and forwards incoming gRPC-Web requests (Content-Type: grpc-web*) to the upstream servers. This feature is enabled by default and is usable using the default configuration, although CORS will need to configured to accept requests from browsers.