Global.asax.cs

using KeyVaultSeries.Core;
using Microsoft.Azure.KeyVault;
using System;

namespace GetSecretsInYourApp
{
    public class Global : System.Web.HttpApplication
    {
        protected void Application_Start(object sender, EventArgs e)
        {
            KeyVaultClient keyVaultClient = new KeyVaultClient(
                new KeyVaultClient.AuthenticationCallback(
                    TokenBasedAccessHelper.GetToken));

            var secretValut = keyVaultClient.GetSecretAsync("[url-to-secret]")
                // Don't try this at home :)
                .GetAwaiter().GetResult().Value;
        }
    }
}