Temporarily drop virtual machine from Azure cloud service for maintenance

Question

We have an Azure Cloud Service with some Virtual Machines running ASP.NET websites. When we upgrade the application we want to drop each VM out of the cloud service so that users don't get a degraded experience until it's been deployed to.

This doesn't seem possible, which suggests we're "doing it wrong".

Can anyone help?

Answer 1

If you're using Windows Azure VMs, not Cloud Services - Web Roles, then you'll have to manage the application update process yourself. A Web Role provides the in-place upgrade and VIP swap feature mentioned previously. Those are great options for handling the application upgrade process.

Answer 2

Naturally during an in-place upgrade Azure will do what you want by what is called "honoring upgrade domains" - role instances will be updated one update domain at a time and restarted (role instances only, not their VMs).

However this is not what I'd recommend to use because if the upgrade goes wrong there's no way to roll it back. The much better way is to deploy a new staging deployment, check that it's running fine, do "swap VIP" and then stop and delete the original deployment.