Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.AspNetCore.SpaServices.Webpack;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Microsoft.EntityFrameworkCore;
using contact_app.Models;
using System.IO;

namespace contact_app
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<ContactAppContext>(options =>
       options.UseSqlServer(Configuration.GetConnectionString("ContactDb")));

            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();
            }

            //Redirect non api calls to angular app that will handle routing of the app. 
            app.Use(async (context, next) =>
            {
                await next();
                if (context.Response.StatusCode == 404 &&
                   !Path.HasExtension(context.Request.Path.Value) &&
                   !context.Request.Path.Value.StartsWith("/api/"))
                {
                    context.Request.Path = "/index.html";
                    await next();
                }
            });


            // configure the app to serve index.html from /wwwroot folder
            app.UseDefaultFiles();
            app.UseStaticFiles();

            // configure the app for usage as api
            app.UseMvcWithDefaultRoute();


        }
    }
}