Startup.cs

using System;
using System.Collections.Generic;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Hosting;
using Microsoft.EntityFrameworkCore;
using JWTAuthAPI.Data;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using JWTAuthAPI.Settings;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.IdentityModel.Tokens;
using System.Text;
using JWTAuthAPI.Services.IdentityService;
using JWTAuthAPI.Services.TokenService;
using Microsoft.OpenApi.Models;
using Microsoft.AspNetCore.Mvc.Authorization;
using Microsoft.AspNetCore.Authorization;

namespace JWTAuthAPI
{
    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<DataContext>(options =>
                options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
            services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
                .AddRoles<IdentityRole>()
                .AddEntityFrameworkStores<DataContext>();

            ConfigureAuthentication(services);

            services.AddScoped<IIdentityService, IdentityService>();
            services.AddScoped<ITokenService, TokenService>();

            services.AddMvc(options =>
                {
                    options.EnableEndpointRouting = false;
                    var policy = new AuthorizationPolicyBuilder()
                        .RequireAuthenticatedUser()
                        .Build();
                    options.Filters.Add(new AuthorizeFilter(policy));
                });

            services.AddSwaggerGen(x =>
            {
                x.SwaggerDoc("v1", new OpenApiInfo { Title = "My API", Version = "v1" });
                x.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
                {
                    Description = "JWT Authorization header using the bearer scheme",
                    Name = "Authorization",
                    In = ParameterLocation.Header,
                    Type = SecuritySchemeType.ApiKey
                });
                x.AddSecurityRequirement(new OpenApiSecurityRequirement
                {
                    {new OpenApiSecurityScheme{Reference = new OpenApiReference
                    {
                        Id = "Bearer",
                        Type = ReferenceType.SecurityScheme
                    }}, new List<string>()}
                });
            });
        }

        private void ConfigureAuthentication(IServiceCollection services)
        {
            var jwtSettings = new JwtSettings();
            Configuration.Bind(nameof(jwtSettings), jwtSettings);
            services.AddSingleton(jwtSettings);

            var tokenValidationParameters = new TokenValidationParameters
            {
                ValidateIssuerSigningKey = true,
                IssuerSigningKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(jwtSettings.Secret)),
                ValidateIssuer = false,
                ValidateAudience = false,
                RequireExpirationTime = false,
                ValidateLifetime = true,
                ClockSkew = TimeSpan.Zero
            };

            services.AddSingleton(tokenValidationParameters);

            services.AddAuthentication(x =>
                {
                    x.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
                    x.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
                    x.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
                })
                .AddJwtBearer(x =>
                {
                    x.SaveToken = true;
                    x.TokenValidationParameters = tokenValidationParameters;
                });
        }

        // 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();
            }
            else
            {
                app.UseHsts();
            }

            app.UseSwagger(option => option.RouteTemplate = "swagger/{documentName}/swagger.json");
            app.UseSwaggerUI(option => { option.SwaggerEndpoint("v1/swagger.json", "My API V1"); });

            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseAuthentication();

            app.UseMvc();
        }
    }
}