Kratos has a series of built-in middleware to deal with common purpose such as logging or metrics. You could also implement Middleware interface to develop your custom middleware to process common business such as the user authentication etc.

Built-in Middleware

Their codes are located in middleware directory.

logging

In middleware/logging, this middleware is for logging the request.

metrics

In middleware/metrics, this middleware is for enabling metric.

recovery

In middleware/recovery，, this middleware is for panic recovery.

status

In middleware/status, this middleware is for transformation of gRPC error.

tracing

In middleware/tracing, this middleware is for enabling trace.

validate

In middleware/validate, this middleware is for parameter validation.

Usage

Register it with ServerOption in NewGRPCServer or NewHTTPServer.

For example:

// http
// define opts
var opts = []http.ServerOption{
    http.Middleware(
        recovery.Recovery(),
        tracing.Server(),
        logging.Server(),
    ),
}
// create server
http.NewServer(opts...)
//grpc
var opts = []grpc.ServerOption{
        grpc.Middleware(
            recovery.Recovery(),
            status.Server(),
            tracing.Server(),
            logging.Server(),
        ),
    }
// create server
grpc.NewServer(opts...)

Custom Middleware

Implement Middleware interface.

(TBD)