gRPC - Logging with interceptor in gRPC service

要紀錄每次 gRPC 的呼叫，可以使用 gRPC interceptor 來做。

建立一個 Interceptor 類別繼承自 gRPC 的 Interceptor，建立個建構子允許注入 Logger，接著覆寫掉會用到的方法，像是 UnaryServerHandler，然後在內部將要記錄的資訊透過 Logger 寫入 Log 即可。

像是下面這邊筆者實作了一個 Interceptor，希望能紀錄每次 gRPC 的調用。

using System.Linq;
using System.Text.Json.Serialization;
using System.Threading.Tasks;
using Grpc.Core;
using Grpc.Core.Interceptors;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;


namespace GrpcServiceInterceptor
{
    public class LoggerInterceptor : Interceptor
    {
        private readonly ILogger<LoggerInterceptor> _logger;


        public LoggerInterceptor(ILogger<LoggerInterceptor> logger)
        {
            _logger = logger;
        }


        public override async Task<TResponse> UnaryServerHandler<TRequest, TResponse>(
            TRequest request,
            ServerCallContext context,
            UnaryServerMethod<TRequest, TResponse> continuation)
        {
            var response = await base.UnaryServerHandler(request, context, continuation);
            Log(MethodType.Unary, request, response, context);


            return response;
        }


        public override async Task<TResponse> ClientStreamingServerHandler<TRequest, TResponse>(
            IAsyncStreamReader<TRequest> requestStream,
            ServerCallContext context,
            ClientStreamingServerMethod<TRequest, TResponse> continuation)
        {
            var response = await base.ClientStreamingServerHandler(requestStream, context, continuation);
            Log(MethodType.ClientStreaming, requestStream, response, context);


            return response;
        }


        public override Task ServerStreamingServerHandler<TRequest, TResponse>(
            TRequest request,
            IServerStreamWriter<TResponse> responseStream,
            ServerCallContext context,
            ServerStreamingServerMethod<TRequest, TResponse> continuation)
        {
            Log(MethodType.ServerStreaming, request, responseStream, context);


            return base.ServerStreamingServerHandler(request, responseStream, context, continuation);
        }


        public override Task DuplexStreamingServerHandler<TRequest, TResponse>(
            IAsyncStreamReader<TRequest> requestStream,
            IServerStreamWriter<TResponse> responseStream,
            ServerCallContext context,
            DuplexStreamingServerMethod<TRequest, TResponse> continuation)
        {
            Log(MethodType.DuplexStreaming, requestStream, responseStream, context);


            return base.DuplexStreamingServerHandler(requestStream, responseStream, context, continuation);
        }


        private void Log<TRequest, TResponse>(MethodType methodType, TRequest request, TResponse response,
            ServerCallContext context)
        {
            _logger.LogInformation(
                $"gRPC call. Type: {methodType}. Request: {request.ToString()}. Response: {response.ToString()}");
        }
    }
}

Interceptor 寫好後掛載進去。

...
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddGrpc(options =>
            {
                var interceptors = options.Interceptors;
                interceptors.Add<LoggerInterceptor>();
                ...
            });
        }
        ...
    }
...