AspNetCoreServer and Duplicate Logging

We’re currently experiencing an issue with Amazon.Lambda.AspNetCoreServer and Logging.

We’re hosting an asp.net core web site in Lambda. The web site works however I’m getting duplicates in the logs in CloudWatch and I haven’t been able to figure out the cause. I’ve removed all the logging setup identified in Amazon.Lambda.Logging.AspNetCore and the behaviour is exactly the same regardless. App settings also has no logging configuration.

Here is an example of what I’m seeing in the log:

• 2020-06-20T20:50:56.705-04:00 START RequestId: fdbd1980-8263-4b5f-8bfc-ef8ec43e0085 Version: $LATEST
• 2020-06-20T20:50:56.705-04:00 [40m[32minfo[39m[22m[49m: Microsoft.Hosting.Lifetime[0]
• 2020-06-20T20:50:56.707-04:00 Application started. Press Ctrl+C to shut down.
• 2020-06-20T20:50:56.708-04:00 [Information] Microsoft.Hosting.Lifetime: Application started. Press Ctrl+C to shut down.
• 2020-06-20T20:50:56.708-04:00 [40m[32minfo[39m[22m[49m: Microsoft.Hosting.Lifetime[0]
• 2020-06-20T20:50:56.708-04:00 Hosting environment: Production
• 2020-06-20T20:50:56.708-04:00 [40m[32minfo[39m[22m[49m: Microsoft.Hosting.Lifetime[0]
• 2020-06-20T20:50:56.708-04:00 Content root path: /var/task
• 2020-06-20T20:50:56.708-04:00 [Information] Microsoft.Hosting.Lifetime: Hosting environment: Production
• 2020-06-20T20:50:56.708-04:00 [Information] Microsoft.Hosting.Lifetime: Content root path: /var/task
• 2020-06-20T20:50:56.880-04:00 [40m[32minfo[39m[22m[49m: Microsoft.AspNetCore.Hosting.Diagnostics[1]
• 2020-06-20T20:50:57.456-04:00 [Information] Project.Classes.GetFileHandler: Started Project.Classes.GetFileHandler
• 2020-06-20T20:50:57.456-04:00 Started Project.Classes.GetFileHandler

Below is a simplified version of my code.

    public class LambdaEntryPoint : Amazon.Lambda.AspNetCoreServer.APIGatewayProxyFunction
    {
        protected override void Init(IWebHostBuilder builder)
        {
            RegisterResponseContentEncodingForContentType("application/pdf",
                    ResponseContentEncoding.Base64);
            builder
                .UseStartup<Startup>();
        }

        protected override void Init(IHostBuilder builder)
        {
        }
    }

    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        public void ConfigureServices(IServiceCollection services)
        {
            IConfigurationSection appSettings = Configuration.GetSection("AppSettings");

            services.Configure<AppSettings>(appSettings);
            services.AddAWSService<IAmazonS3>();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseRouting();
			
            app.MapWhen(
                context => context.Request.Path.ToString().EndsWith("file.ashx"),
                appBranch => {
                    // ... optionally add more middleware to this branch
                    appBranch.UseGetFileHandler();
                });
        }
    }

    public class GetFileHandler
    {
        public GetFileHandler(RequestDelegate next)
        { }

        public async Task Invoke(HttpContext context, ILogger<GetFileHandler> logger)
        {
            logger.LogInformation("Started " + this.GetType());
        }
    }

Thanks for any help.

Regards Artin

[ayongbannayan]

I resolved it by using the work around I specified. Specifically clearing the providers set by the library and resetting them myself. I don’t know if the underlying issue has been resolved.

[ayongbannayan]

I’ve been able to work around the issue by doing the following in the LambdaEntryPoint class:

        protected override void Init(IWebHostBuilder builder)
        {
            RegisterResponseContentEncodingForContentType("application/pdf",
                    ResponseContentEncoding.Base64);
            builder
                .ConfigureLogging((hostingContext, logging) =>
                {
                    logging.ClearProviders();
                    logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                    logging.AddLambdaLogger(hostingContext.Configuration, "Logging");
                })
                .UseStartup<Startup>();
        }

Haven’t been able to figure out what in the base class would be causing this issue.