Startup.cs

using Etch.OrchardCore.OutputCache.Controllers;
using Etch.OrchardCore.OutputCache.Drivers;
using Etch.OrchardCore.OutputCache.Policies;
using Etch.OrchardCore.OutputCache.Settings;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using OrchardCore.Admin;
using OrchardCore.DisplayManagement.Handlers;
using OrchardCore.Entities;
using OrchardCore.Modules;
using OrchardCore.Mvc.Core.Utilities;
using OrchardCore.Navigation;
using OrchardCore.Settings;
using System;

namespace Etch.OrchardCore.OutputCache
{
    public class Startup : StartupBase
    {
        private readonly AdminOptions _adminOptions;

        public Startup(IOptions<AdminOptions> adminOptions)
        {
            _adminOptions = adminOptions.Value;
        }

        public override void ConfigureServices(IServiceCollection services)
        {
            services.AddScoped<IDisplayDriver<ISite>, OutputCacheSettingsDisplayDriver>();

            services.AddScoped<INavigationProvider, AdminMenu>();

            services.AddOutputCache(options =>
            {
                var siteService = services.BuildServiceProvider().GetService<ISiteService>();
                var settings = siteService.GetSiteSettingsAsync().Result.As<OutputCacheSettings>();

                options.DefaultExpirationTimeSpan = new TimeSpan(0, settings.Expiration, 0);

                options.AddBasePolicy(new DefaultOrchardCorePolicy(settings));
            });
        }

        public override void Configure(IApplicationBuilder app, IEndpointRouteBuilder routes, IServiceProvider serviceProvider)
        {
            app.UseOutputCache();

            routes.MapAreaControllerRoute(
                name: "OutputCachePurge",
                areaName: "Etch.OrchardCore.OutputCache",
                pattern: _adminOptions.AdminUrlPrefix + "/OutputCache/Purge",
                defaults: new { controller = typeof(PurgeController).ControllerName(), action = nameof(PurgeController.Index) }
            );
        }
    }
}