Re: [libvirt-users] virsh snapshot-create-as: change umask on snapshots

On Friday, March 22, 2019, 12:36:16 PM CDT, Peter Krempa <pkrempa(a)redhat.com&gt; wrote: On Wed, Mar 20, 2019 at 15:48:43 -0500, Eric Blake wrote: > On 3/20/19 1:50 PM, Mircea Husz wrote: > > I scripted the creation of snapshots and it works fine. Now I'd like to run the script as non-root. > > > > virsh snapshot-create-as --domain hq-live-v01 \ > >      --name snappy \ > >      --diskspec vda,file=/var/lib/libvirt/images/hq-live-v01.snappy,snapshot=external \ > >      --diskspec vdb,file=/var/lib/libvirt/images/hq-live-storage.snappy,snapshot=external \ > >      --disk-only --quiesce --atomic > > > > This fragment creates the snapshots, but get created with mode 0600: > > -rw-------  1 qemu qemu     393216 Mar 19 17:08 hq-live-storage.snappy > > -rw-------  1 qemu qemu    1048576 Mar 19 17:08 hq-live-v01.snappy > > > > The user account is in the libvirt group and has permissions to do everything except delete the files created by the snapshot, all I need is to get the snapshots created with 0660 mode. > > > > This is on a Centos 7.6 installation.  What knobs do I need to turn to control the umask? > > I'm not sure if you can force libvirt to create the files with a > different mask, but perhaps a workaround would be to pre-create the > files yourself with desired permissions, then tell virsh to > --reuse-external (so that libvirt no longer has to try and create the > files, and thus doesn't mess with permissions). --reuse-external is good only for using a custom-formatted image. Libvirt will chown the image to qemu:qemu if you don't disable relabelling. This is possible to do via the <seclabel> even in a snapshot <disk> definition.

Note that it's not documented yet and also does not conform to the schema, but the parser happily parses it and the code uses the correct <seclabel> then. I have a not-sufficiently-tested patch that adds the schema (and IIRC also docs) which I planned to send after testing.