SimpleRequestLogger 2.0.2

SimpleRequestLogger

This package provides a small and customizable ASP.NET Core middleware for structured logging of requests using Microsoft.Extensions.Logging. The built-in request logging is a bit noisy and emits multiple events per request. With SimpleRequestLogger you can fit all the information you need in a single log entry:

// Plaintext
[21:51:46.5705 INFO] GET / responded 200 in 31 ms.

// JSON
{
    "Time": "21:51:46.5705",
    "Level": "INFO",
    "Message": "GET / responded 200 in 31 ms.",
    "Properties": {
        "Method": "GET",
        "Path": "/",
        "QueryString": "",
        "StatusCode": 200,
        "ElapsedMs": 31
    }
}

Installation

You can install the NuGet package via the NuGet Package Manager inside Visual Studio or via the console:

// Package Manager Console
Install-Package SimpleRequestLogger

// .NET Core CLI
dotnet add package SimpleRequestLogger

Usage

The only thing you should do is simply add the middleware to the request pipeline.

Default configuration

By default, SimpleRequestLogger logs all requests at information log level with message template "{Method} {Path}{QueryString} responded {StatusCode} in {ElapsedMs} ms.". To use the middleware you should only add a single line:

app.UseRequestLogging();

Custom configuration

It is possible to customize the message template, to change the log level based on status code and to disable logging for specific paths. SimpleRequestLogger uses Microsoft.Extensions.Configuration and would by default expect a section RequestLogging.

"RequestLogging": {
    "MessageTemplate": "{Scheme} {Method} {Path} => {StatusCode}",
    "IgnorePaths": [ "/health", "/static/*" ]
}

It is also possible to pass a custom configuration section:

app.UseRequestLogging("YourCustomSection:CustomSubsectionRequestLogging");

To change the log level based on status code, you should pass a delegate to the middleware:

app.UseRequestLogging(statusCode => (statusCode < 400) ? LogLevel.Information : LogLevel.Error);

You might as well have both custom configuration section and a log level selector.

app.UseRequestLogging("YourCustomSection:CustomSubsectionRequestLoging", 
    statusCode => (statusCode < 400) ? LogLevel.Information : LogLevel.Error);

Properties

• Method
• Path
• QueryString
• Header* - A Pascal case field name will be transformed to Kebab case. Example: HeaderFooBar ⇒ foo-bar
• Protocol
• Scheme
• RemoteIpAddress - If you log this property you might want to consider adding UseForwardedHeaders() to your pipeline.
• Claim* - A Pascal case claim type will be transformed to Kebab case. Example: ClaimFooBar ⇒ foo-bar
• StatusCode
• ElapsedMs

Pipeline placement

You might want to consider placing SimpleRequestLogger after request-heavy middleware like UseStaticFiles() if those requests are not interesting for you (alternatively, you might ignore those via the configuration).

If SimpleRequestLogger catches an exception, the request will be logged with a status code 500 and the exception will be rethrown. If you have an error handling middleware that alters the response status code based on exception type, you should consider adding SimpleRequestLogger before it.

Exceptions

In normal circumstances, SimpleRequestLogger should not throw exceptions when handling requests.

On startup, when the middleware is instantiated, the configuration is verified. MessageTemplate and IgnorePaths are checked for validity. Additionally, it is also ensured that the log level selector delegate will not throw for the standard response status codes. In case of a problem with the configuration, an InvalidOperationException is thrown.

Performance

SimpleRequestLogger adds a negligible performance overhead to every request.

Benchmarks

The scenarios are run on a test host without other middleware.

Support

If you spot any problems and/or have improvement ideas, please share them via the issue tracker.