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RockLib.Logging.AspNetCore package

This package contains context providers and action filters for use by AspNetCore applications.

Context providers

To automatically capture information from the current HttpContext for each log sent, call the AddHttpContextProvider extension method when adding the logger to a service collection.

Note: A logger must have Transient lifetime (which is the default) in order for any of the context providers mentioned in this document to function properly.

using RockLib.Logging.AspNetCore;
using RockLib.Logging.DependencyInjection;

public void ConfigureServices(IServiceCollection services)
{
    services.AddLogger()
        .AddConsoleLogProvider()
        .AddHttpContextProvider();
}

Logs sent by this logger will include the following extended properties:

Extended property Description
Method The request method (GET, POST, etc.)
Path The route pattern (if available), or request path (if not)
UserAgent The 'User-Agent' header of the request
Referer The 'Referer' header of the request
RemoteIpAddress The remote IP address of the request's underlying connection
X-Forwarded-For The 'X-Forwarded-For' header of the request

Logs sent by this logger will also have their CorrelationId property set using the ICorrelationIdAccessor associated with the HttpContext via the RockLib.DistributedTracing.AspNetCore package's GetCorrelationIdAccessor extension method.

To customize the name of the correlation id header, configure its options:

services.Configure<CorrelationIdContextProviderOptions>(options =>
    options.CorrelationIdHeader = "MyCorrelationIdHeader");

There are also individual context providers available (configuring the correlation id header is the same as above):

services.AddLogger()
    .AddConsoleLogProvider()
    .AddContextProvider<RequestMethodContextProvider>()
    .AddContextProvider<PathContextProvider>()
    .AddContextProvider<UserAgentContextProvider>()
    .AddContextProvider<ReferrerContextProvider>()
    .AddContextProvider<RemoteIpAddressContextProvider>()
    .AddContextProvider<ForwardedForContextProvider>()
    .AddContextProvider<CorrelationIdContextProvider>();

Logging action filters

To automatically record an info log for a controller action, decorate it with the [InfoLog] attribute. Doing so will result in an info log with a message in the format "Request handled by {actionName}.". The log will also include, when applicable: the exception thrown by the action, and the "ResponseStatusCode", "ResultType", and "ResultObject" extended properties.

// GET math/triple/4
[InfoLog]
[HttpGet("triple/{num}")]
public int Triple(int num)
{
    return num * 3;
}

Using the route "Math/Triple/4" will result in a log entry with the following values:

LogEntry property Value
Message "Request handled by MyAspNetCoreApp.Controllers.MathController.Triple (MyAspNetCoreApp)."
ExtendedProperties.num 4
ExtendedProperties.ResponseStatusCode 200
ExtendedProperties.ResultType "ObjectResult"
ExtendedProperties.ResultObject 12

Instead of decorating the action method, a controller can be decorated with [InfoLog]. In this case, all action methods in the controller will be logged.

namespace MyAspNetCoreApp.Controllers
{
    [InfoLog]
    [ApiController]
    [Route("[controller]")]
    public class MathController : ControllerBase
    {
    }
}

The [InfoLog] action filter can also be registered globally, in Startup.ConfigureServices (or wherever you configure your services), as an option in the call to the AddControllers extension method:

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers(options => options.Filters.Add(typeof(InfoLogAttribute)));
}

Optional parameters

The [InfoLog] action filter has two optional parameters.

Parameter name Description
messageFormat A format string for the log message. The action name is used as the {0} placeholder
loggerName The name of the logger that is registered with the service collection.

Route not found middleware

To automatically record a log whenever a non-existant endpoint is hit, use the RouteNotFoundMiddleware class. This can easily be done by using the UseRouteNotFoundLogging extension.

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.UseRouteNotFoundLogging();
}

By default, a logger with the default name (which is empty string) will be used to send a Warn level log with the message 'There was an attempt to access a non-existant endpoint.' These defaults can be overridden by configuring a RouteNotFoundMiddlewareOptions.

public void ConfigureServices(IServiceCollection services)
{
    services.Configure<RouteNotFoundMiddlewareOptions>(options => {
        options.LoggerName = "NotDefault";
        options.LogLevel = LogLevel.Error;
        options.LogMessage = "Some other message about hitting a 404";
    });
}