HTTP logging in ASP.NET Core

Note

This isn't the latest version of this article. For the current release, see the .NET 8 version of this article.

Warning

This version of ASP.NET Core is no longer supported. For more information, see .NET and .NET Core Support Policy. For the current release, see the .NET 8 version of this article.

Important

This information relates to a pre-release product that may be substantially modified before it's commercially released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

For the current release, see the .NET 8 version of this article.

HTTP logging is a middleware that logs information about incoming HTTP requests and HTTP responses. HTTP logging provides logs of:

  • HTTP request information
  • Common properties
  • Headers
  • Body
  • HTTP response information

HTTP logging can:

  • Log all requests and responses or only requests and responses that meet certain criteria.
  • Select which parts of the request and response are logged.
  • Allow you to redact sensitive information from the logs.

HTTP logging can reduce the performance of an app, especially when logging the request and response bodies. Consider the performance impact when selecting fields to log. Test the performance impact of the selected logging properties.

Warning

HTTP logging can potentially log personally identifiable information (PII). Consider the risk and avoid logging sensitive information.

Enable HTTP logging

HTTP logging is enabled by calling AddHttpLogging and UseHttpLogging, as shown in the following example:

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(o => { });

var app = builder.Build();

app.UseHttpLogging();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}
app.UseStaticFiles();

app.MapGet("/", () => "Hello World!");

app.Run();

The empty lambda in the preceding example of calling AddHttpLogging adds the middleware with the default configuration. By default, HTTP logging logs common properties such as path, status-code, and headers for requests and responses.

Add the following line to the appsettings.Development.json file at the "LogLevel": { level so the HTTP logs are displayed:

 "Microsoft.AspNetCore.HttpLogging.HttpLoggingMiddleware": "Information"

With the default configuration, a request and response is logged as a pair of messages similar to the following example:

info: Microsoft.AspNetCore.HttpLogging.HttpLoggingMiddleware[1]
      Request:
      Protocol: HTTP/2
      Method: GET
      Scheme: https
      PathBase:
      Path: /
      Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
      Host: localhost:52941
      User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36 Edg/118.0.2088.61
      Accept-Encoding: gzip, deflate, br
      Accept-Language: en-US,en;q=0.9
      Upgrade-Insecure-Requests: [Redacted]
      sec-ch-ua: [Redacted]
      sec-ch-ua-mobile: [Redacted]
      sec-ch-ua-platform: [Redacted]
      sec-fetch-site: [Redacted]
      sec-fetch-mode: [Redacted]
      sec-fetch-user: [Redacted]
      sec-fetch-dest: [Redacted]
info: Microsoft.AspNetCore.HttpLogging.HttpLoggingMiddleware[2]
      Response:
      StatusCode: 200
      Content-Type: text/plain; charset=utf-8
      Date: Tue, 24 Oct 2023 02:03:53 GMT
      Server: Kestrel

HTTP logging options

To configure global options for the HTTP logging middleware, call AddHttpLogging in Program.cs, using the lambda to configure HttpLoggingOptions.

using Microsoft.AspNetCore.HttpLogging;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.All;
    logging.RequestHeaders.Add("sec-ch-ua");
    logging.ResponseHeaders.Add("MyResponseHeader");
    logging.MediaTypeOptions.AddText("application/javascript");
    logging.RequestBodyLogLimit = 4096;
    logging.ResponseBodyLogLimit = 4096;
    logging.CombineLogs = true;
});

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}

app.UseStaticFiles();

app.UseHttpLogging(); 

app.Use(async (context, next) =>
{
    context.Response.Headers["MyResponseHeader"] =
        new string[] { "My Response Header Value" };

    await next();
});

app.MapGet("/", () => "Hello World!");

app.Run();

Note

In the preceding sample and following samples, UseHttpLogging is called after UseStaticFiles, so HTTP logging is not enabled for static files. To enable static file HTTP logging, call UseHttpLogging before UseStaticFiles.

LoggingFields

HttpLoggingOptions.LoggingFields is an enum flag that configures specific parts of the request and response to log. HttpLoggingOptions.LoggingFields defaults to RequestPropertiesAndHeaders | ResponsePropertiesAndHeaders.

RequestHeaders and ResponseHeaders

RequestHeaders and ResponseHeaders are sets of HTTP headers that are logged. Header values are only logged for header names that are in these collections. The following code adds sec-ch-ua to the RequestHeaders, so the value of the sec-ch-ua header is logged. And it adds MyResponseHeader to the ResponseHeaders, so the value of the MyResponseHeader header is logged. If these lines are removed, the values of these headers are [Redacted].

using Microsoft.AspNetCore.HttpLogging;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.All;
    logging.RequestHeaders.Add("sec-ch-ua");
    logging.ResponseHeaders.Add("MyResponseHeader");
    logging.MediaTypeOptions.AddText("application/javascript");
    logging.RequestBodyLogLimit = 4096;
    logging.ResponseBodyLogLimit = 4096;
    logging.CombineLogs = true;
});

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}

app.UseStaticFiles();

app.UseHttpLogging(); 

app.Use(async (context, next) =>
{
    context.Response.Headers["MyResponseHeader"] =
        new string[] { "My Response Header Value" };

    await next();
});

app.MapGet("/", () => "Hello World!");

app.Run();

MediaTypeOptions

MediaTypeOptions provides configuration for selecting which encoding to use for a specific media type.

using Microsoft.AspNetCore.HttpLogging;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.All;
    logging.RequestHeaders.Add("sec-ch-ua");
    logging.ResponseHeaders.Add("MyResponseHeader");
    logging.MediaTypeOptions.AddText("application/javascript");
    logging.RequestBodyLogLimit = 4096;
    logging.ResponseBodyLogLimit = 4096;
    logging.CombineLogs = true;
});

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}

app.UseStaticFiles();

app.UseHttpLogging(); 

app.Use(async (context, next) =>
{
    context.Response.Headers["MyResponseHeader"] =
        new string[] { "My Response Header Value" };

    await next();
});

app.MapGet("/", () => "Hello World!");

app.Run();

This approach can also be used to enable logging for data that isn't logged by default (for example, form data, which might have a media type such as application/x-www-form-urlencoded or multipart/form-data).

MediaTypeOptions methods

RequestBodyLogLimit and ResponseBodyLogLimit

using Microsoft.AspNetCore.HttpLogging;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.All;
    logging.RequestHeaders.Add("sec-ch-ua");
    logging.ResponseHeaders.Add("MyResponseHeader");
    logging.MediaTypeOptions.AddText("application/javascript");
    logging.RequestBodyLogLimit = 4096;
    logging.ResponseBodyLogLimit = 4096;
    logging.CombineLogs = true;
});

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}

app.UseStaticFiles();

app.UseHttpLogging(); 

app.Use(async (context, next) =>
{
    context.Response.Headers["MyResponseHeader"] =
        new string[] { "My Response Header Value" };

    await next();
});

app.MapGet("/", () => "Hello World!");

app.Run();

CombineLogs

Setting CombineLogs to true configures the middleware to consolidate all of its enabled logs for a request and response into one log at the end. This includes the request, request body, response, response body, and duration.

using Microsoft.AspNetCore.HttpLogging;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.All;
    logging.RequestHeaders.Add("sec-ch-ua");
    logging.ResponseHeaders.Add("MyResponseHeader");
    logging.MediaTypeOptions.AddText("application/javascript");
    logging.RequestBodyLogLimit = 4096;
    logging.ResponseBodyLogLimit = 4096;
    logging.CombineLogs = true;
});

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}

app.UseStaticFiles();

app.UseHttpLogging(); 

app.Use(async (context, next) =>
{
    context.Response.Headers["MyResponseHeader"] =
        new string[] { "My Response Header Value" };

    await next();
});

app.MapGet("/", () => "Hello World!");

app.Run();

Endpoint-specific configuration

For endpoint-specific configuration in minimal API apps, a WithHttpLogging extension method is available. The following example shows how to configure HTTP logging for one endpoint:

app.MapGet("/response", () => "Hello World! (logging response)")
    .WithHttpLogging(HttpLoggingFields.ResponsePropertiesAndHeaders);

For endpoint-specific configuration in apps that use controllers, the [HttpLogging] attribute is available. The attribute can also be used in minimal API apps, as shown in the following example:

app.MapGet("/duration", [HttpLogging(loggingFields: HttpLoggingFields.Duration)]
    () => "Hello World! (logging duration)");

IHttpLoggingInterceptor

IHttpLoggingInterceptor is the interface for a service that can be implemented to handle per-request and per-response callbacks for customizing what details get logged. Any endpoint-specific log settings are applied first and can then be overridden in these callbacks. An implementation can:

  • Inspect a request or response.
  • Enable or disable any HttpLoggingFields.
  • Adjust how much of the request or response body is logged.
  • Add custom fields to the logs.

Register an IHttpLoggingInterceptor implementation by calling AddHttpLoggingInterceptor<T> in Program.cs. If multiple IHttpLoggingInterceptor instances are registered, they're run in the order registered.

The following example shows how to register an IHttpLoggingInterceptor implementation:

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.Duration;
});
builder.Services.AddHttpLoggingInterceptor<SampleHttpLoggingInterceptor>();

The following example is an IHttpLoggingInterceptor implementation that:

  • Inspects the request method and disables logging for POST requests.
  • For non-POST requests:
    • Redacts request path, request headers, and response headers.
    • Adds custom fields and field values to the request and response logs.
using Microsoft.AspNetCore.HttpLogging;

namespace HttpLoggingSample;

internal sealed class SampleHttpLoggingInterceptor : IHttpLoggingInterceptor
{
    public ValueTask OnRequestAsync(HttpLoggingInterceptorContext logContext)
    {
        if (logContext.HttpContext.Request.Method == "POST")
        {
            // Don't log anything if the request is a POST.
            logContext.LoggingFields = HttpLoggingFields.None;
        }

        // Don't enrich if we're not going to log any part of the request.
        if (!logContext.IsAnyEnabled(HttpLoggingFields.Request))
        {
            return default;
        }

        if (logContext.TryDisable(HttpLoggingFields.RequestPath))
        {
            RedactPath(logContext);
        }

        if (logContext.TryDisable(HttpLoggingFields.RequestHeaders))
        {
            RedactRequestHeaders(logContext);
        }

        EnrichRequest(logContext);

        return default;
    }

    public ValueTask OnResponseAsync(HttpLoggingInterceptorContext logContext)
    {
        // Don't enrich if we're not going to log any part of the response
        if (!logContext.IsAnyEnabled(HttpLoggingFields.Response))
        {
            return default;
        }

        if (logContext.TryDisable(HttpLoggingFields.ResponseHeaders))
        {
            RedactResponseHeaders(logContext);
        }

        EnrichResponse(logContext);

        return default;
    }

    private void RedactPath(HttpLoggingInterceptorContext logContext)
    {
        logContext.AddParameter(nameof(logContext.HttpContext.Request.Path), "RedactedPath");
    }

    private void RedactRequestHeaders(HttpLoggingInterceptorContext logContext)
    {
        foreach (var header in logContext.HttpContext.Request.Headers)
        {
            logContext.AddParameter(header.Key, "RedactedHeader");
        }
    }

    private void EnrichRequest(HttpLoggingInterceptorContext logContext)
    {
        logContext.AddParameter("RequestEnrichment", "Stuff");
    }

    private void RedactResponseHeaders(HttpLoggingInterceptorContext logContext)
    {
        foreach (var header in logContext.HttpContext.Response.Headers)
        {
            logContext.AddParameter(header.Key, "RedactedHeader");
        }
    }

    private void EnrichResponse(HttpLoggingInterceptorContext logContext)
    {
        logContext.AddParameter("ResponseEnrichment", "Stuff");
    }
}

With this interceptor, a POST request doesn't generate any logs even if HTTP logging is configured to log HttpLoggingFields.All. A GET request generates logs similar to the following example:

info: Microsoft.AspNetCore.HttpLogging.HttpLoggingMiddleware[1]
      Request:
      Path: RedactedPath
      Accept: RedactedHeader
      Host: RedactedHeader
      User-Agent: RedactedHeader
      Accept-Encoding: RedactedHeader
      Accept-Language: RedactedHeader
      Upgrade-Insecure-Requests: RedactedHeader
      sec-ch-ua: RedactedHeader
      sec-ch-ua-mobile: RedactedHeader
      sec-ch-ua-platform: RedactedHeader
      sec-fetch-site: RedactedHeader
      sec-fetch-mode: RedactedHeader
      sec-fetch-user: RedactedHeader
      sec-fetch-dest: RedactedHeader
      RequestEnrichment: Stuff
      Protocol: HTTP/2
      Method: GET
      Scheme: https
info: Microsoft.AspNetCore.HttpLogging.HttpLoggingMiddleware[2]
      Response:
      Content-Type: RedactedHeader
      MyResponseHeader: RedactedHeader
      ResponseEnrichment: Stuff
      StatusCode: 200
info: Microsoft.AspNetCore.HttpLogging.HttpLoggingMiddleware[4]
      ResponseBody: Hello World!
info: Microsoft.AspNetCore.HttpLogging.HttpLoggingMiddleware[8]
      Duration: 2.2778ms

Logging configuration order of precedence

The following list shows the order of precedence for logging configuration:

  1. Global configuration from HttpLoggingOptions, set by calling AddHttpLogging.
  2. Endpoint-specific configuration from the [HttpLogging] attribute or the WithHttpLogging extension method overrides global configuration.
  3. IHttpLoggingInterceptor is called with the results and can further modify the configuration per request.

HTTP Logging is a middleware that logs information about incoming HTTP requests and HTTP responses. HTTP logging provides logs of:

  • HTTP request information
  • Common properties
  • Headers
  • Body
  • HTTP response information

HTTP Logging is valuable in several scenarios to:

  • Record information about incoming requests and responses.
  • Filter which parts of the request and response are logged.
  • Filtering which headers to log.

HTTP Logging can reduce the performance of an app, especially when logging the request and response bodies. Consider the performance impact when selecting fields to log. Test the performance impact of the selected logging properties.

Warning

HTTP Logging can potentially log personally identifiable information (PII). Consider the risk and avoid logging sensitive information.

Enabling HTTP logging

HTTP Logging is enabled with UseHttpLogging, which adds HTTP logging middleware.

var builder = WebApplication.CreateBuilder(args);

var app = builder.Build();

app.UseHttpLogging();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}
app.UseStaticFiles();

app.MapGet("/", () => "Hello World!");

app.Run();

By default, HTTP Logging logs common properties such as path, status-code, and headers for requests and responses. Add the following line to the appsettings.Development.json file at the "LogLevel": { level so the HTTP logs are displayed:

 "Microsoft.AspNetCore.HttpLogging.HttpLoggingMiddleware": "Information"

The output is logged as a single message at LogLevel.Information.

Sample request output

HTTP Logging options

To configure the HTTP logging middleware, call AddHttpLogging in Program.cs.

using Microsoft.AspNetCore.HttpLogging;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.All;
    logging.RequestHeaders.Add("sec-ch-ua");
    logging.ResponseHeaders.Add("MyResponseHeader");
    logging.MediaTypeOptions.AddText("application/javascript");
    logging.RequestBodyLogLimit = 4096;
    logging.ResponseBodyLogLimit = 4096;

});

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}

app.UseStaticFiles();

app.UseHttpLogging(); 

app.Use(async (context, next) =>
{
    context.Response.Headers["MyResponseHeader"] =
        new string[] { "My Response Header Value" };

    await next();
});

app.MapGet("/", () => "Hello World!");

app.Run();

Note

In the preceding sample and following samples, UseHttpLogging is called after UseStaticFiles, so HTTP logging is not enabled for static file. To enable static file HTTP logging, call UseHttpLogging before UseStaticFiles.

LoggingFields

HttpLoggingOptions.LoggingFields is an enum flag that configures specific parts of the request and response to log. HttpLoggingOptions.LoggingFields defaults to RequestPropertiesAndHeaders | ResponsePropertiesAndHeaders.

RequestHeaders

Headers are a set of HTTP Request Headers that are allowed to be logged. Header values are only logged for header names that are in this collection. The following code logs the request header "sec-ch-ua". If logging.RequestHeaders.Add("sec-ch-ua"); is removed, the value of the request header "sec-ch-ua" is redacted. The following highlighted code calls HttpLoggingOptions.RequestHeaders and HttpLoggingOptions.ResponseHeaders :

using Microsoft.AspNetCore.HttpLogging;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.All;
    logging.RequestHeaders.Add("sec-ch-ua");
    logging.ResponseHeaders.Add("MyResponseHeader");
    logging.MediaTypeOptions.AddText("application/javascript");
    logging.RequestBodyLogLimit = 4096;
    logging.ResponseBodyLogLimit = 4096;

});

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}

app.UseStaticFiles();

app.UseHttpLogging(); 

app.Use(async (context, next) =>
{
    context.Response.Headers["MyResponseHeader"] =
        new string[] { "My Response Header Value" };

    await next();
});

app.MapGet("/", () => "Hello World!");

app.Run();

MediaTypeOptions

MediaTypeOptions provides configuration for selecting which encoding to use for a specific media type.

using Microsoft.AspNetCore.HttpLogging;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.All;
    logging.RequestHeaders.Add("sec-ch-ua");
    logging.ResponseHeaders.Add("MyResponseHeader");
    logging.MediaTypeOptions.AddText("application/javascript");
    logging.RequestBodyLogLimit = 4096;
    logging.ResponseBodyLogLimit = 4096;

});

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}

app.UseStaticFiles();

app.UseHttpLogging(); 

app.Use(async (context, next) =>
{
    context.Response.Headers["MyResponseHeader"] =
        new string[] { "My Response Header Value" };

    await next();
});

app.MapGet("/", () => "Hello World!");

app.Run();

This approach can also be used to enable logging for data that is not logged by default. For example, form data, which might have a media type such as application/x-www-form-urlencoded or multipart/form-data.

MediaTypeOptions methods

RequestBodyLogLimit and ResponseBodyLogLimit

using Microsoft.AspNetCore.HttpLogging;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpLogging(logging =>
{
    logging.LoggingFields = HttpLoggingFields.All;
    logging.RequestHeaders.Add("sec-ch-ua");
    logging.ResponseHeaders.Add("MyResponseHeader");
    logging.MediaTypeOptions.AddText("application/javascript");
    logging.RequestBodyLogLimit = 4096;
    logging.ResponseBodyLogLimit = 4096;

});

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
}

app.UseStaticFiles();

app.UseHttpLogging(); 

app.Use(async (context, next) =>
{
    context.Response.Headers["MyResponseHeader"] =
        new string[] { "My Response Header Value" };

    await next();
});

app.MapGet("/", () => "Hello World!");

app.Run();