Logging

GenHTTP uses the default logging mechanism of .NET Core and allows to create loggers via the IServer interface. By default, the host will add a console logger.

Logging Information

The following code shows to obtain a logger from the server instance in a custom IHandler implementation. It is recommended to create the logger once in the preparation phase and store the reference somewhere. You can use this pattern anywhere where you have access to IServer (e.g. via request.Server).

using GenHTTP.Api.Content;
using GenHTTP.Api.Infrastructure;
using GenHTTP.Api.Protocol;

using Microsoft.Extensions.Logging;

namespace GenHTTP.Playground;

public class MyHandler : IHandler
{
    private ILogger? _logger;

    public ValueTask PrepareAsync(IServer server)
    {
        _logger = server.Logging.CreateLogger<MyHandler>();
        return ValueTask.CompletedTask;
    }

    public ValueTask<IResponse?> HandleAsync(IRequest request)
    {
        _logger?.LogInformation("I am logging important information");   
        
        return new();
    }
    
}

Customize Logging

The Logging() method of the host builder allows to pass a custom logging factory that should be used by the application.

The following example uses Open Telemetry for logging:

using Microsoft.Extensions.Logging;
using OpenTelemetry.Logs;

var factory = LoggerFactory.Create(builder =>
{
    builder.AddOpenTelemetry(logging =>
    {
        logging.AddOtlpExporter();
    });
});

return await Host.Create()
                 .Logging(factory)
                 .Handler(handler)
                 .Defaults()
                 .RunAsync();

To disable logging, you can pass a null logger:

Host.Create()
    .Logging(NullLoggerFactory.Instance);

Request Logging

By default, GenHTTP will install a concern that logs every request and the response it generated.

info: GenHTTP.Requests[217529272]
      GET /api/ - HTTP 200 - 12 bytes - 18521.44 ms
info: GenHTTP.Requests[217529272]
      GET /favicon.ico - HTTP 404 - 0 bytes - 149.87 ms
info: GenHTTP.Requests[217529272]
      GET /assets/GenHTTP.Playground.xml - HTTP 200 - 0 bytes - 103.06 ms

If you would like to opt-out of request logging, you can pass a flag to the Logging() method of the host builder.

var logger = LoggerFactory.Create(b => b.AddConsole());

return await Host.Create()
                 .Logging(logger, logRequests: false)
                 .Handler(handler)
                 .Defaults()
                 .RunAsync();