The Ultimate Guide to gRPC in ASP.NET Core/

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Applying Advanced Logging in a gRPC Application

Applying Advanced Logging in a gRPC Application

Learn how to apply advanced logging to gRPC.

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To see the logs produced by the framework, we need to configure the logging provider and logging level. There's also a way to apply custom logging to capture what the framework is doing. To do so, we can configure logging interceptors for both the client and server.

There are many types of scenarios where using logging interceptors would be needed. For example, certain systems accept logs in a specific proprietary format, which cannot be applied by using standard libraries. Also, we might want to apply additional custom metadata to our logs, which interceptors will allow us to achieve easily.

We briefly covered gRPC interceptors when we looked at the advanced gRPC configuration. In this lesson, we'll cover them in more detail and see how they can be used for logging. We will start with the following project setup.

{
  "profiles": {
    "BasicGrpcService": {
      "commandName": "Project",
      "dotnetRunMessages": true,
      "launchBrowser": false,
      "applicationUrl": "http://127.0.0.1:5100;https://127.0.0.1:7100",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    }
  }
}
Initial project setup

We'll first add an interceptor to the gRPC server application. Then, we'll do the same to the client application.

Adding a logging interceptor to the gRPC server

We'll open the BasicGrpcService project folder and add the LoggingInterceptor.cs file to it with the following content.

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using Grpc.Core;
using Grpc.Core.Interceptors;
using Microsoft.Extensions.Logging;
namespace BasicGrpcService;
public class LoggingInterceptor : Interceptor
{
    private readonly ILogger<LoggingInterceptor> _logger;
    public LoggingInterceptor(ILogger<LoggingInterceptor>  logger)
    {
        _logger = logger;
    }
    public override async Task<TResponse> UnaryServerHandler<TRequest, TResponse>(TRequest request, ServerCallContext context, UnaryServerMethod<TRequest, TResponse> continuation)
    {
        LogCall(context);
        try
        {
            return await continuation(request, context);
        }
        catch (Exception ex)
        {
            LogException(ex);
            throw;
        }
    }
    public override async Task<TResponse> ClientStreamingServerHandler<TRequest, TResponse>(IAsyncStreamReader<TRequest> requestStream, ServerCallContext context, ClientStreamingServerMethod<TRequest, TResponse> continuation)
    {
        LogCall(context);
        try
        {
            return await continuation(requestStream, context);
        }
        catch (Exception ex)
        {
            LogException(ex);
            throw;
        }
    }
    public override async Task ServerStreamingServerHandler<TRequest, TResponse>(TRequest request, IServerStreamWriter<TResponse> responseStream, ServerCallContext context, ServerStreamingServerMethod<TRequest, TResponse> continuation)
    {
        LogCall(context);
        try
        {
            await continuation(request, responseStream, context);
        }
        catch (Exception ex)
        {
            LogException(ex);
            throw;
        }
    }
    public override async Task DuplexStreamingServerHandler<TRequest, TResponse>(IAsyncStreamReader<TRequest> requestStream, IServerStreamWriter<TResponse> responseStream, ServerCallContext context, DuplexStreamingServerMethod<TRequest, TResponse> continuation)
    {
        LogCall(context);
        try
        {
            await continuation(requestStream, responseStream, context);
        }
        catch (Exception ex)
        {
            LogException(ex);
            throw;
        }
    }
    private void LogCall(ServerCallContext context)
    {
        _logger.LogDebug($"gRPC request: {context.GetHttpContext().Request.Path}");
    }
    private void LogException(Exception ex)
    {
        _logger.LogError(ex, "gRPC error occurred");
    }
}

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