Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.ResponseCompression;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Mole.API.Models;

namespace Mole.API
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                .AddEnvironmentVariables();
            Configuration = builder.Build();
        }

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<ComputationManager>(Configuration);// Read configuration appsettings.json

            services.AddResponseCompression(x => {
                x.EnableForHttps = true;
                x.Providers.Add<GzipCompressionProvider>();
            }); //allow gzip compression

            services.AddCors(options =>
            {
                options.AddPolicy("CorsPolicy",
                    builder => builder.
                        AllowAnyOrigin().
                        AllowAnyMethod().
                        AllowAnyHeader().
                        AllowCredentials().
                        WithExposedHeaders("Content-Disposition"));
            });// allow Cross-origin resource sharing            

            services.AddMvc();// Add framework services.
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            app.UseExceptionHandler("/Index/Error");
            
            app.UseCors("CorsPolicy"); // has to be BEFORE UseMvc method
            app.UseStaticFiles(); // allow download files from wwwroot
            app.UseResponseCompression();
            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "Index",
                    template: "{controller=Index}/{action=Index}");
            });

            
        }
    }
}