[pve-devel] [RFC_V2 manager] Storage: remove guest images in storage contendview

[Fabian Grünbichler]

On Mon, Nov 12, 2018 at 11:15:33AM +0100, Dietmar Maurer wrote:
> > If an image on storage has not referenced to any guest or
> > replication config, we can safely delete it on the GUI.
> > Also, if a config exists on another node, we can delete it too.
> 
> Only if the image is on local storage ...
> 
> > But if an image has a <vmid> encoded in the image name and a guest
> > exists in the cluster with this VMID then it must a lost image of the VM.
> 
> OK
> 
> > In this case, a rescan will add it back to the config.
> 
> I would not rescan here - it is too complex (needs to be done inside a worker task).
> 
> Also, I would remove the replication config code - simple remove the image
> if the user request it.
> 
> > This follows the logic of 'qm rescan',
> > what assume if an image exists on a node,
> > Images that are marked as unused in the config are referred.
> > 
> > This call can't be in the store because of cycles dependencies.
> > The extra Subclass is necessary for the "fragmentDelimiter"
> > which is used for forwarding the correct volume name for dir storages.
> 
> Without the replication/rescan logic, it should be possible to implement inside
> pve-storage - please can you try?

I wonder if it would not make sense to make this a GUI only feature? we
have all the components already in the API:
1) get volumes on a storage FOO, including vmid as determined by storage
plugin
2) get config of VM/CT BAR and check if volid BAZ is referenced
3) user can (given appropriate permissions) just call the regular DELETE
storage/content API path

there might be a small race (at least QemuServer's importdisk allocs an
image and only adds the reference to it in the config after qemu-img
convert is done), but for a manual action the admin/VM user probably
knows when such an action is concurrently running.

any non-GUI users can already trivially build this functionality via the
API/pvesh/CLI interfaces anyway, since all the 'logic' is just filtering
returned values and passing them to the next API/.. call.