Question

Your team runs a stateless web application on a managed instance group (MIG) of 12 Compute Engine VMs behind a load balancer. You need to deploy a new application version by updating to a newer boot disk image, but you must ensure that at least 10 instances remain serving traffic throughout the rollout with no manual VM recreation. What is the recommended approach?

Accepted Answer

Create a new instance template with the updated image and start a rolling update on the MIG with maxUnavailable set to 2

Answer

Edit the existing instance template in place to reference the new image, then restart each VM individually

Answer

Delete the MIG and recreate it with a new instance template that uses the updated image

Answer

Manually stop each VM, change its boot disk image, and start it again one at a time