Startup.cs

using Amazon.DynamoDBv2;
using DynamoDB.Library.DynamoDB;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;
using System.IO;

namespace DynamoDB
{
    public class Startup
    {
        public IConfigurationRoot Configuration { get; set; }

        public Startup()
        {
            Configuration = new ConfigurationBuilder().
                SetBasePath(Directory.GetCurrentDirectory()).
                AddJsonFile("appsettings.json").Build();
        }
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
            services.AddDefaultAWSOptions(Configuration.GetAWSOptions());

            Environment.SetEnvironmentVariable("AWS_SECRET_ACCESS_KEY", Configuration["AWS:SecurityKey"]);
            Environment.SetEnvironmentVariable("AWS_ACCESS_KEY_ID", Configuration["AWS:AccessKey"]);
            Environment.SetEnvironmentVariable("AWS_REGION", Configuration["AWS:Region"]);
            services.AddAWSService<IAmazonDynamoDB>();
            services.AddSingleton<IDynamoDBExamples, DynamoDBExamples>();
            services.AddSingleton<IDeleteTable, DeleteTable>();
            services.AddSingleton<IAddItem, AddItem>();
            services.AddSingleton<IGetItem, GetItem>();
            services.AddSingleton<IUpdateItem, UpdateItem>();
            services.AddSingleton<IDeleteItem, DeleteItem>();
        }

        // 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.UseStaticFiles();
            app.UseRouting();
            app.UseCors();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
                //endpoints.MapControllerRoute("default", "{controller=Home}/{action=Index}");
            });
        }
    }
}