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The general attitude towards VMs should be that they are cattle, not pets - any services/workflows running on a VM should be easily replicable so that an individual host is not required to be kept around indefinitely. There are many ways to simplify setting up a VM, such as Magnum clusters and Heat stacks.
A good lifecycle management process also promotes good service management practices.
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Configuration management is your friend - can create machines with packages pre-installed
If you’re running a service - design for high availability so that one machine going down for maintenance doesn’t take the service down with it
For one-off VMs - use Openstack Volumes Volume Management in OpenStack or other non-root-disk storage so that data isn’t lost when cycling VMs
Stick to a reboot schedule
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