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.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

using AutoMapper;
using Swashbuckle.AspNetCore.Swagger;

using Sandbox.Models;
using Sandbox.Models.DataManager;
using Sandbox.Models.Repository;

namespace Sandbox
{
    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)
        {
            var hostname = Environment.GetEnvironmentVariable("SQLSERVER_HOST") ?? "localhost";
            var password = Environment.GetEnvironmentVariable("SQLSERVER_SA_PASSWORD");
            var connString = $"Server={hostname};User ID=sa;Password={password};";

            services.AddDbContext<UserContext>(opts => opts.UseSqlServer(connString));
            services.AddScoped<IRoleRepository, RoleManager>();
            services.AddScoped<IUserRepository, UserManager>();
            services.AddScoped<IUnitOfWork, UnitOfWork>();
            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
            services.AddAutoMapper();
            services.AddSwaggerGen(config => {  
                config.SwaggerDoc("v1", new Info {  
                    Version = "v1",  
                    Title = "Sandbox API",  
                    Description = "ASP.NET Core Web API for Sandbox"  
                });  
            });
        }

        // 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();
            }
            else
            {
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            // Enable middleware to serve generated Swagger as a JSON endpoint.
            app.UseSwagger();

            // Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.), 
            // specifying the Swagger JSON endpoint.
            app.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "Sandbox API V1");
            });
            app.UseMvc();
        }
    }
}