Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authentication.AzureAD.UI;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Authorization;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Swashbuckle.AspNetCore.Swagger;

namespace AspNetCore.AzureAd.Swagger
{
    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.AddAuthentication(AzureADDefaults.JwtBearerAuthenticationScheme)
                .AddAzureADBearer(options => Configuration.Bind("AzureAd", options));


            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new Info { Title = "My API", Version = "v1" });
                c.AddSecurityDefinition("oauth2", new OAuth2Scheme
                {
                    Type = "oauth2",
                    Flow = "implicit",
                    AuthorizationUrl = $"https://login.microsoftonline.com/{Configuration["AzureAD:TenantId"]}/oauth2/authorize",
                    Scopes = new Dictionary<string, string>
                    {
                        { "read", "Access API" }
                    }
                });

                c.AddSecurityRequirement(new Dictionary<string, IEnumerable<string>>
                {
                    { "oauth2", new[] { "read" } }
                });
            });
        }

        // 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
            {
                app.UseHsts();
            }

            app.UseAuthentication();
            app.UseHttpsRedirection();
            app.UseMvc();


            app.UseSwagger();

            app.UseSwaggerUI(c =>
            {
                c.OAuthClientId(Configuration["Swagger:ClientId"]);
                c.OAuthClientSecret(Configuration["Swagger:ClientSecret"]);
                c.OAuthRealm(Configuration["AzureAD:ClientId"]);
                c.OAuthAppName("My API V1");
                c.OAuthScopeSeparator(" ");
                c.OAuthAdditionalQueryStringParams(new Dictionary<string, string>() { { "resource", Configuration["AzureAD:ClientId"] } });
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
            });
        }
    }
}