Startup.cs

using Azure.Identity;
using Azure.Security.KeyVault.Secrets;
using Azure.Core;
using System;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.EntityFrameworkCore;
using Microsoft.OpenApi.Models;
using TodoApi.Models;

namespace TodoApi
{
    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)
        {
          /*  SecretClientOptions options = new SecretClientOptions()
            {
                Retry =
                {
                    Delay= TimeSpan.FromSeconds(2),
                    MaxDelay = TimeSpan.FromSeconds(16),
                    MaxRetries = 5,
                    Mode = RetryMode.Exponential
                }
            };
            var client = new SecretClient(new Uri("https://mykeyvault89.vault.azure.net/"), new DefaultAzureCredential(),options);
            
            KeyVaultSecret secret = client.GetSecret("AppSecret");
            
            string secretValue = secret.Value;*/
            services.AddControllers();

            // Register the Swagger generator, defining 1 or more Swagger documents
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "My API", Version = "v1" });
                //c.SwaggerDoc("v1", new OpenApiInfo { Title = "My API", Version = secretValue });
            });

            services.AddDbContext<TodoContext>(options => options.UseInMemoryDatabase("TodoList"));
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            // Enable middleware to serve generated Swagger as a JSON endpoint.
            app.UseSwagger();

            // Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),
            // specifying the Swagger JSON endpoint.
            app.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
            });

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            //app.UseHttpsRedirection();

            app.UseDefaultFiles();

            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthorization();

            /*SecretClientOptions options = new SecretClientOptions()
            {
                Retry =
                {
                    Delay= TimeSpan.FromSeconds(2),
                    MaxDelay = TimeSpan.FromSeconds(16),
                    MaxRetries = 5,
                    Mode = RetryMode.Exponential
                }
            };
            var client = new SecretClient(new Uri("https://myKV9898.vault.azure.net/"), new DefaultAzureCredential(),options);
            
            KeyVaultSecret secret = client.GetSecret("AppSecret");
            
            string secretValue = secret.Value;*/
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}