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HTTP Logging in ASP.NET Core

  • 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 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 (e.g. 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();