Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;


namespace BooksWebApi
{
    public class Startup
    {
		public IConfiguration Configuration { get; set; }
		public Startup(IHostingEnvironment env)
		{
			var builder = new ConfigurationBuilder()
			 .SetBasePath(env.ContentRootPath)
			 .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
			 .AddEnvironmentVariables();

			Configuration = builder.Build();
      }
       
      // This method gets called by the runtime. Use this method to add services to the container.
      public void ConfigureServices(IServiceCollection services)
      {
          services.AddMvc();
      }

      // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
      public void Configure(IApplicationBuilder app, IHostingEnvironment env)
      {
		if (env.IsDevelopment())
		{
			app.UseDeveloperExceptionPage();
			app.UseBrowserLink();
		}
		else
		{
			app.UseExceptionHandler("/Error");
		}

		app.UseMvc();
	  }
   }
}