HTTP Logging in ASP.NET Core

HTTP Logging is a middleware that logs information about 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.

Enabling HTTP logging

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

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

    app.UseRouting();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapGet("/", async context =>
        {
            await context.Response.WriteAsync("Hello World!");
        });
    });
}

By default, HTTP Logging logs common properties such as path, status-code, and headers for requests and responses. The output is logged as a single message at LogLevel.Information.

HTTP Logging options

To configure the HTTP logging middleware, call AddHttpLogging in ConfigureServices.

public void ConfigureServices(IServiceCollection services)
{
    services.AddHttpLogging(logging =>
    {
        // Customize HTTP logging here.
        logging.LoggingFields = HttpLoggingFields.All;
        logging.RequestHeaders.Add("My-Request-Header");
        logging.ResponseHeaders.Add("My-Response-Header");
        logging.MediaTypeOptions.AddText("application/javascript");
        logging.RequestBodyLogLimit = 4096;
        logging.ResponseBodyLogLimit = 4096;
    });
}

LoggingFields

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

public void ConfigureServices(IServiceCollection services)
{
    services.AddHttpLogging(logging =>
    {
        // Customize HTTP logging here.
        logging.LoggingFields = HttpLoggingFields.All;
        logging.RequestHeaders.Add("My-Request-Header");
        logging.ResponseHeaders.Add("My-Response-Header");
        logging.MediaTypeOptions.AddText("application/javascript");
        logging.RequestBodyLogLimit = 4096;
        logging.ResponseBodyLogLimit = 4096;
    });
}

RequestHeaders

RequestHeaders 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.

public void ConfigureServices(IServiceCollection services)
{
    services.AddHttpLogging(logging =>
    {
        // Customize HTTP logging here.
        logging.LoggingFields = HttpLoggingFields.All;
        logging.RequestHeaders.Add("My-Request-Header");
        logging.ResponseHeaders.Add("My-Response-Header");
        logging.MediaTypeOptions.AddText("application/javascript");
        logging.RequestBodyLogLimit = 4096;
        logging.ResponseBodyLogLimit = 4096;
    });
}

ResponseHeaders

ResponseHeaders are a set of HTTP Response Headers that are allowed to be logged. Header values are only logged for header names that are in this collection.

public void ConfigureServices(IServiceCollection services)
{
    services.AddHttpLogging(logging =>
    {
        // Customize HTTP logging here.
        logging.LoggingFields = HttpLoggingFields.All;
        logging.RequestHeaders.Add("My-Request-Header");
        logging.ResponseHeaders.Add("My-Response-Header");
        logging.MediaTypeOptions.AddText("application/javascript");
        logging.RequestBodyLogLimit = 4096;
        logging.ResponseBodyLogLimit = 4096;
    });
}

MediaTypeOptions

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

public void ConfigureServices(IServiceCollection services)
{
    services.AddHttpLogging(logging =>
    {
        // Customize HTTP logging here.
        logging.LoggingFields = HttpLoggingFields.All;
        logging.RequestHeaders.Add("My-Request-Header");
        logging.ResponseHeaders.Add("My-Response-Header");
        logging.MediaTypeOptions.AddText("application/javascript");
        logging.RequestBodyLogLimit = 4096;
        logging.ResponseBodyLogLimit = 4096;
    });
}

MediaTypeOptions methods

• public void AddText(string contentType)
  • Adds a contentType to be used for logging as text using UTF-8 encoding.
• public void AddText(string contentType, Encoding encoding)
  • Adds a contentType to be used for logging as text using the specified encoding.
• public void AddBinary(MediaTypeHeaderValue mediaType)
  • Adds a MediaTypeHeaderValue to be used for logging as binary.
• public void AddBinary(string contentType)
  • Adds a content to be used for logging as text using the specified content type.
• public void Clear()
  • Clears all MediaTypes.

RequestBodyLogLimit

Maximum request body size to log, in bytes. Defaults to 32 KB.

public void ConfigureServices(IServiceCollection services)
{
    services.AddHttpLogging(logging =>
    {
        // Customize HTTP logging here.
        logging.LoggingFields = HttpLoggingFields.All;
        logging.RequestHeaders.Add("My-Request-Header");
        logging.ResponseHeaders.Add("My-Response-Header");
        logging.MediaTypeOptions.AddText("application/javascript");
        logging.RequestBodyLogLimit = 4096;
        logging.ResponseBodyLogLimit = 4096;
    });
}

ResponseBodyLogLimit

Maximum response body size to log, in bytes. Defaults to 32 KB.

public void ConfigureServices(IServiceCollection services)
{
    services.AddHttpLogging(logging =>
    {
        // Customize HTTP logging here.
        logging.LoggingFields = HttpLoggingFields.All;
        logging.RequestHeaders.Add("My-Request-Header");
        logging.ResponseHeaders.Add("My-Response-Header");
        logging.MediaTypeOptions.AddText("application/javascript");
        logging.RequestBodyLogLimit = 4096;
        logging.ResponseBodyLogLimit = 4096;
    });
}