Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddHealthChecks(checks =>
    {
        // First parameter is the URL you want to check
        // The second parameter is the CacheDuration of how long you want to hold onto the HealthCheckResult
        // The default is 5 minutes, and in my case, I don't really want any cache at all
        // because I don't want to wait up to 5 minutes if my service goes down to be notified about it
        checks.AddUrlCheck("https://github.com", TimeSpan.FromMilliseconds(1));
    });

    services.AddMvc();
}