Startup.cs

using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.OpenApi.Models;
using WebAPI.Authentication;
using WebAPI.Data;
using WebAPI.Services;

namespace WebAPI
{
    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.AddSwaggerGen(c => 
            { 
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "My Api", Version = "v1" });
                c.AddSecurityDefinition("basic", new OpenApiSecurityScheme
                {
                    Name = "Authorization",
                    Type = SecuritySchemeType.Http,
                    Scheme = "basic",
                    In = ParameterLocation.Header,
                    Description = "Basic Authorization header using the Bearer scheme."
                });
                c.AddSecurityRequirement(new OpenApiSecurityRequirement
                {
                    {
                          new OpenApiSecurityScheme
                            {
                                Reference = new OpenApiReference
                                {
                                    Type = ReferenceType.SecurityScheme,
                                    Id = "basic"
                                }
                            },
                            new string[] {}
                    }
                });
            });

            services.AddCors();

            services.AddControllers();

            services.AddAuthentication("BasicAuthentication")
                .AddScheme<AuthenticationSchemeOptions, BasicAuthenticationHandler>("BasicAuthentication", null);

            // configure DI for application services
            services.AddScoped<IUserService, UserService>();

            services.AddSingleton<InitData>();
        }

        // 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.UseHttpsRedirection();

            app.UseRouting();

            app.UseCors(x => x
                .AllowAnyOrigin()
                .AllowAnyMethod()
                .AllowAnyHeader());

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

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

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