How to configure a Serilog sink for logging to CloudWatch

Question

I would appreciate some guidance in setting up a Serilog sink for AWS CloudWatch with .NET Core. I'm using appsettings.json for configuration but I am unable to put the settings in the logger. When trying to write log information to CloudWatch this error appears:

An error occurred while starting the application.
AmazonClientException: No RegionEndpoint or ServiceURL configured

Amazon.Runtime.ClientConfig.Validate() in ClientConfig.cs, line 446

AmazonClientException: No RegionEndpoint or ServiceURL configured

Amazon.Runtime.ClientConfig.Validate() in ClientConfig.cs
Amazon.Runtime.AmazonServiceClient..ctor(AWSCredentials credentials, ClientConfig config) in AmazonServiceClient.cs
AWS.Logger.Core.AWSLoggerCore..ctor(AWSLoggerConfig config, string logType) in AWSLoggerCore.cs
AWS.Logger.SeriLog.AWSSink..ctor(AWSLoggerConfig loggerConfiguration, IFormatProvider iFormatProvider, ITextFormatter textFormatter) in AWSSink.cs
AWS.Logger.SeriLog.AWSLoggerSeriLogExtension.AWSSeriLog(LoggerSinkConfiguration loggerConfiguration, IConfiguration configuration, IFormatProvider iFormatProvider, ITextFormatter textFormatter) in AWSLoggerSeriLogExtension.cs
...
Microsoft.AspNetCore.Hosting.ConventionBasedStartup.Configure(IApplicationBuilder app)
Microsoft.Extensions.DependencyInjection.IServiceCollectionExtensions+InjectApiVersionRoutePolicy+<>c__DisplayClass2_0.<Configure>b__0(IApplicationBuilder app)
Microsoft.AspNetCore.Server.IISIntegration.IISSetupFilter+<>c__DisplayClass4_0.<Configure>b__0(IApplicationBuilder app)
Microsoft.AspNetCore.HostFilteringStartupFilter+<>c__DisplayClass0_0.<Configure>b__0(IApplicationBuilder app)
Microsoft.AspNetCore.Hosting.Internal.AutoRequestServicesStartupFilter+<>c__DisplayClass0_0.<Configure>b__0(IApplicationBuilder builder)
Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()

My code is as follows:

In Startup.cs:

public Startup(IHostingEnvironment env)
{
    Configuration = new ConfigurationBuilder()
        .SetBasePath(env.ContentRootPath)
        .AddJsonFile("appsettings.json")
        .AddEnvironmentVariables()
        .Build();
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    loggerFactory.AddConsole(Configuration.GetSection("Logging"));
    Log.Logger = new LoggerConfiguration()
        .ReadFrom.Configuration(Configuration.GetSection("AWS.Logging"))
        .WriteTo.AWSSeriLog(Configuration)
        .CreateLogger();

    app.UseMvc();
}

My appsettings.json:

{
  "Logging": {
    "LogLevel": {
      "Default": "Warning"
    }
  },
  "AWS.Logging": {
    "Region": "eu-west-1",
    "LogGroup": "MyLogGroup",
    "LogLevel": {
      "Default": "Information",
      "System": "Information",
      "Microsoft": "Information"
    }
  },
  "AllowedHosts": "*"
}

Credentials for AWS from my developer machine are set by using environment variables:

AWS_ACCESS_KEY_ID=xxxxxxxxxx
AWS_DEFAULT_REGION=eu-west-1
AWS_SECRET_ACCESS_KEY=xxxxxxxxxxxxxxxxx

Answer 1

I don't think the previous solution is complete, it misses the WriteTo part, the minimal configuration should look like this:

"Serilog": {
    "Using": [
      "AWS.Logger.SeriLog"
    ],
    "LogGroup": "MyLogGroup",
    "Region": "eu-west-1",
    "WriteTo": [
      {
        "Name": "AWSSeriLog",
        "Args": {
          "textFormatter": "Serilog.Formatting.Compact.RenderedCompactJsonFormatter, Serilog.Formatting.Compact"
        }
      }
    ]
  }

This requires Serilog.Formatting.Compact library to be installed (I recommend using it, much neater log records), you can also use the default:

"textFormatter": "Serilog.Formatting.Json.JsonFormatter, Serilog"

This setup is utilising the AWS supplied library AWS.Logger.Serilog, do not forget to add it to your NuGet packages.

Also, if you are not running the app inside the AWS, the AWS credentials are to be provided.

Answer 2

Just in case anyone has the same problem, this appsettings.json solved it:

{
  "Logging": {
    "LogLevel": {
      "Default": "Warning"
    }
  },
  "Serilog": {
    "Using": [ "AWS.Logger.SeriLog" ]
    "Region": "eu-west-1",
    "LogGroup": "MyLogGroup",
    "LogLevel": {
      "Default": "Information",
      "System": "Information",
      "Microsoft": "Information"
    }
  },
  "AllowedHosts": "*"
}