Startup.cs

using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.IdentityModel.Tokens;
using Microsoft.OpenApi.Models;

using PaymentsAPI.Repositories;
using PaymentsAPI.Services;

using System;
using System.Collections.Generic;
using System.IO;
using System.Reflection;
using System.Text;

namespace PaymentsAPI
{
    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.AddControllers();
            services.AddSwaggerGen(c =>
            {                
                var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.XML";
                var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
                
                c.IncludeXmlComments(xmlPath, includeControllerXmlComments: true);

                c.SwaggerDoc("v1", new OpenApiInfo { Title = "ToDoList API", Version = "v1" });

                c.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
                {
                    Description = "JWT Authorization header using the Bearer scheme. <br> " +
                    "Please Enter 'Bearer' [space] and then your token in the text input below. Example: \"Bearer eyJraWQ ...\". <br> " +
                    "To obtain such token, execute the 'GET api/User' request.",
                    Name = "Authorization",
                    In = ParameterLocation.Header,
                    Type = SecuritySchemeType.ApiKey,
                    Scheme = "Bearer"
                });

                c.AddSecurityRequirement(new OpenApiSecurityRequirement()
                {
                    {
                        new OpenApiSecurityScheme
                        {
                            Reference = new OpenApiReference
                            {
                                Type = ReferenceType.SecurityScheme,
                                Id = "Bearer"
                            },
                            Scheme = "oauth2",
                            Name = "Bearer",
                            In = ParameterLocation.Header,

                        },
                        new List<string>()
                    }
                });
            });

            var secret = Environment.GetEnvironmentVariable("JWT_SECRET");
            var key = Encoding.ASCII.GetBytes(secret);

            services.AddAuthentication(x =>
            {
                x.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
                x.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
            })
            .AddJwtBearer(x =>
            {
                x.RequireHttpsMetadata = true;
                x.SaveToken = true;
                x.TokenValidationParameters = new TokenValidationParameters
                {
                    ValidateIssuerSigningKey = true,
                    IssuerSigningKey = new SymmetricSecurityKey(key),
                    ValidateIssuer = false,
                    ValidateAudience = false
                };
            });

            services.AddDbContext<ToDoDbContext>(options =>
                options.UseSqlServer(Configuration["ConnectionStrings:Default"]));

            services.AddScoped<IToDoListService, ToDoListService>();
            services.AddScoped<IToDoListRepository, ToDoListRepository>();
            services.AddScoped<IUserService, UserService>();

        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "PaymentsAPI v1"));
            }

            app.UseHttpsRedirection();

            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();
            app.UseDeveloperExceptionPage();


            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}