Serilog Sink Not Logging From Lambda

Question

For my WebAPI, .UseSerilog() seems to work as expected on the LocalEntryPoint om my.Net Core 3.1 api running on my local box. However, when i deploy to AWS Lambda using LambdaEntryPoint's IWebHostBuilder it does not seem to log anything. My LambdaEntryPoint's IWebhostBuilder is:

 protected override void Init(IWebHostBuilder builder)
    {
        try
        {
            builder
               .ConfigureLogging(logger =>
                {
                  logger.ClearProviders();
                  logger.AddSerilog(dispose: true);
                );
                
              
            Log.Information("The IWebHostBuilder has been built");

        }
        catch (System.Exception ex)
        {
            Log.Fatal(ex, ex.Message);
        }
        finally
        {
            Log.CloseAndFlush();
        }

       
    }

Has anyone found a way to log using serilog in applications deployed in AWS Lambda?

Answer 1

You're going to want to use the.UseSerilog() extension menthod of the IWebHostBuilder directly like so:

protected override void Init(IWebHostBuilder builder)
{
     builder
         .UseSerilog()
         .UseStartup<Startup>();
}

My understanding is that this overrides the default ILogger implementation of Microsoft.Extensions.Logging namespace.

Then in your Startup class's ConfigureServices(IServiceCollection services) method you would implement a singleton of the Serilog.Core.Logger like so:

var loggerConfig = new LoggerConfiguration()
                .ReadFrom.Configuration(Configuration)
                .Enrich.WithThreadId()
                .Enrich.FromLogContext()
                .Enrich.WithProperty("Application", "MyApplicationName")
                .Enrich.WithProperty("Machine", Environment.MachineName)
                .WriteTo.Console(new RenderedCompactJsonFormatter());

var logger = loggerConfig.CreateLogger();
            services.AddSingleton<Logger>(logger);

At this point you've dependency injected the logger into your aspnetcore app and can use it in a controller like so:

private readonly Logger _log;

public DefaultController(Logger logger)
{
     _log = logger;
}

[HttpGet]
public IActionResult Get()
{
     _log.Information("This is an example of an information log");
     return Ok(new string[] { "value1", "value2" });
}