jellyfin/Jellyfin.Server/Extensions/ApiApplicationBuilderExtensions.cs

using Jellyfin.Server.Middleware;
using Microsoft.AspNetCore.Builder;

namespace Jellyfin.Server.Extensions
{
    /// <summary>
    /// Extensions for adding API specific functionality to the application pipeline.
    /// </summary>
    public static class ApiApplicationBuilderExtensions
    {
        /// <summary>
        /// Adds swagger and swagger UI to the application pipeline.
        /// </summary>
        /// <param name="applicationBuilder">The application builder.</param>
        /// <returns>The updated application builder.</returns>
        public static IApplicationBuilder UseJellyfinApiSwagger(this IApplicationBuilder applicationBuilder)
        {
            applicationBuilder.UseSwagger();

            // Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),
            // specifying the Swagger JSON endpoint.
            return applicationBuilder.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "Jellyfin API V1");
            });
        }
    }
}