Startup.cs

using System;
using System.Collections.Generic;
using System.IO.Compression;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.ResponseCompression;
using Microsoft.AspNetCore.SpaServices.Webpack;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using vue_blog.Data;

namespace vue_blog
{
    public class Startup
    {
        public IConfiguration _config { get; }

        public Startup(IConfiguration config)
        {
            _config = config;
        }
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddEntityFrameworkNpgsql().AddDbContext<AppDbContext>(options =>
            {
                var env = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");

                string connStr;

                if (env == "Development")
                {
                    // Use connection string from file.
                    connStr = _config.GetConnectionString("ApplicationDbContext");
                }
                else
                {
                    // Use connection string provided at runtime by Heroku.
                    var connUrl = Environment.GetEnvironmentVariable("DATABASE_URL");

                    // Parse connection URL to connection string for Npgsql
                    connUrl = connUrl.Replace("postgres://", string.Empty);
                    var pgUserPass = connUrl.Split("@")[0];
                    var pgHostPortDb = connUrl.Split("@")[1];
                    var pgHostPort = pgHostPortDb.Split("/")[0];
                    var pgDb = pgHostPortDb.Split("/")[1];
                    var pgUser = pgUserPass.Split(":")[0];
                    var pgPass = pgUserPass.Split(":")[1];
                    var pgHost = pgHostPort.Split(":")[0];
                    var pgPort = pgHostPort.Split(":")[1];

                    connStr = $"Server={pgHost};Port={pgPort};User Id={pgUser};Password={pgPass};Database={pgDb}";
                }

                // Whether the connection string came from the local development configuration file
                // or from the environment variable from Heroku, use it to set up your DbContext.
                options.UseNpgsql(connStr);
            });
            services.AddResponseCompression(options=> {
                options.Providers.Add<GzipCompressionProvider>();
                options.Providers.Add<BrotliCompressionProvider>();
            });
            services.Configure<GzipCompressionProviderOptions>(options =>
            {
                options.Level = CompressionLevel.Optimal;
            });
            services.AddIdentity<IdentityUser, IdentityRole>(
                option =>
                {
                    option.Password.RequireDigit = false;
                    option.Password.RequireNonAlphanumeric = false;
                    option.Password.RequiredLength = 6;
                    option.Password.RequireUppercase = false;
                }

                )
                .AddEntityFrameworkStores<AppDbContext>();
            services.AddMvc(option => option.EnableEndpointRouting = false);
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env )
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();

                app.UseWebpackDevMiddleware(new WebpackDevMiddlewareOptions
                {
                    HotModuleReplacement = true
                });
            }
            app.UseResponseCompression();
            app.UseStaticFiles();
            app.UseAuthentication();

            app.UseRouting();
            app.UseAuthorization();
            app.UseEndpoints(builder =>
            {

                builder.MapControllers();
                builder.MapFallbackToController("Index", "Home");
            });
            //app.UseSpa(spa =>
            //{
            //    if (env.IsDevelopment())
            //        spa.Options.SourcePath = "ClientApp";
            //    else
            //        spa.Options.SourcePath = "dist";
            //});
        }
    }
}