program.cs

public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureAppConfiguration((webBuilder) => {
                    var config = webBuilder.Build();
                    var mode = (KeyVaultUsage)Enum.Parse(typeof(KeyVaultUsage), (config["Secrets:Mode"]));
                    if (mode != KeyVaultUsage.UseLocalSecretStore)
                    {
                        KeyVaultOptions kvc = config.GetSection("Secrets").Get<KeyVaultOptions>();
                        if (mode == KeyVaultUsage.UseClientSecret)
                        {
                            webBuilder.AddAzureKeyVault(kvc.KeyVaultUri, kvc.ClientId, kvc.ClientSecret);
                        }
                        else //UseMsi
                        {
                            var tokenProvider = new AzureServiceTokenProvider();
                            //Create the Key Vault client
                            var kvClient = new KeyVaultClient((authority, resource, scope) => tokenProvider.KeyVaultTokenCallback(authority, resource, scope));
                            //Add Key Vault to configuration pipeline
                            webBuilder.AddAzureKeyVault(kvc.KeyVaultUri, kvClient, new DefaultKeyVaultSecretManager());
                        }
                    }
                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    
                    
                    
                    
                    webBuilder.UseStartup<Startup>();
                });