Azure RoleEnvironment.Changing event not being called in ASP.NET MVC 5 - asp.net-mvc

Question

I am trying to use the Azure Runtime Reconfiguration Pattern to allow me to change a appSetting in the normal Web.config file via PowerShell (later by Microsoft Azure Web Sites Management Library).
My problem is that the RoleEnvironment.Changing event is not being called in my MVC app, so the web app is being restarted. I have placed event set up code in the MVC Application_Start as described in the Azure article, i.e.
protected void Application_Start()
{
RoleEnvironment.Changing += RoleEnvironment_Changing;
RoleEnvironment.Changed += RoleEnvironment_Changed;
//normal MVC code etc...
AreaRegistration.RegisterAllAreas();
}
The event handlers are a straight copy of the handled from the Azure article and look like this:
private const string CustomSettingName = "TestConfig";
public static string TestConfigValue;
private static void RoleEnvironment_Changing(object sender,
RoleEnvironmentChangingEventArgs e)
{
RoleLogs.Add("RoleEnvironment_Changing: started");
var changedSettings = e.Changes.OfType<RoleEnvironmentConfigurationSettingChange>()
.Select(c => c.ConfigurationSettingName).ToList();
Trace.TraceInformation("Changing notification. Settings being changed: "
+ string.Join(", ", changedSettings));
if (changedSettings
.Any(settingName => !string.Equals(settingName, CustomSettingName,
StringComparison.Ordinal)))
{
Console.WriteLine("Cancelling dynamic configuration change (restarting).");
RoleLogs.Add("RoleEnvironment_Changing: restarting!");
// Setting this to true will restart the role gracefully. If Cancel is not
// set to true, and the change is not handled by the application, the
// application will not use the new value until it is restarted (either
// manually or for some other reason).
e.Cancel = true;
}
else
{
RoleLogs.Add("RoleEnvironment_Changing: change is OK. Not restarting");
Console.WriteLine("Handling configuration change without restarting. ");
}
}
private static void RoleEnvironment_Changed(object sender,
RoleEnvironmentChangedEventArgs e)
{
RoleLogs.Add("RoleEnvironment_ChangED: Starting");
Console.WriteLine("Updating instance with new configuration settings.");
foreach (var settingChange in
e.Changes.OfType<RoleEnvironmentConfigurationSettingChange>())
{
if (string.Equals(settingChange.ConfigurationSettingName,
CustomSettingName,
StringComparison.Ordinal))
{
// Execute a function to update the configuration of the component.
RoleLogs.Add("RoleEnvironment_ChangED: TestConfig has changed");
Console.WriteLine("TestConfig has changed.");
TestConfigValue = RoleEnvironment.GetConfigurationSettingValue(CustomSettingName);
}
}
}
I have added logs which prove that my RoleEnvironment_Changing and RoleEnvironment_Changed are not being called in the MVC WebApp which means the WebApp is restarted when I change an appSetting via PowerShell. This also means the RoleEnvironment.Changing event never gets to the WebJob.
I am using Azure SDK 2.7.0
Any ideas?
UPDATE
#richag gave me an answer, which made me realise that my problem is because I am using a App Service rather than a Cloud Service. This SO answer and plus this video (see at 5:00mins) talks about the difference (Note: the video is old so the name of the web app is different, but the concept is the same).
I don't really want to change this late in the development, and I have worked round the problem another way. Maybe on the next project and will look at Cloud Services as I can see some positives, like better control of my WebJobs configuration.

Answer 1

From the runtime reconfiguration pattern: "Microsoft Azure Cloud Services roles detect and expose two events that are raised when the hosting environment detects a change to the ServiceConfiguration.cscfg files" These events are not fired if you make changes to app.config/web.config files. Only when the cloud service configuration is changed, i.e. if you upload a new configuration file through the azure portal's configure tab or change a setting directly on the azure portal.

Answer 2

According to the debugger, none of the following events are fired when I update the Azure Portal to change an AppSetting for an ASP.NET WebAPI app:
RoleEnvironment.Changing
RoleEnvironment.Changed
RoleEnvironment.StatusCheck
RoleEnvironment.SimultaneousChanging
RoleEnvironment.SimultaneousChanged
RoleEnvironment.Stopping
Do others have different experience?