Disable libvirt base file cleanup by default

[Joe T]

Hello,

This is related to the following previous bugs:

bug #1029674
bug #1078594

I see that the image_cache_manager_interval was temporarily changed to 0 to effectively disable images from being removed. It looks like it has been restored to a non-zero number.

Both as a systems administrator responsible for OpenStack environments and as someone who was bit by this feature being enabled, I feel that remove_unused_base_images should be False as default. Having a "delete" setting turned on by default can be very dangerous. No matter how many precautions are taken, some scenarios will still slip by. In my opinion, it is a better operational problem to have someone report an abundance of unused images that they can opt-in to delete rather than having a user report images that have been deleted without them understanding why and not being able to restore them.

If I understand the difference between remove_unused_base_images and image_cache_manager_interval, the latter will not enable any of the image cache features to run at all. In an odd way, I still find the cache manager useful to run - as long as if nothing is removed without the user explicitly configuring Nova to do so. If the logs are reporting that certain files are up for deletion, this can help the user understand what will happen if they turn remove_unused_base_images on.

Please let me know if you have any questions or if I am not understanding something correctly.

Thanks,
Joe

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/22040

[Joe Gordon (jogo)]

patch was abandoned