backport librbd librados py3 string encoding fixes

[Edward Hope-Morley]

[Impact]
Requesting back port of py3 encoding fixes to Mimic so that consumers of that code don't get strings returned with invalid encodings when run under py3.

[Test Case]

sudo apt install -y python3-rados
cat << EOF | python3
import rados
name = 'ceph'
conf = '/etc/ceph/ceph.conf'
user = 'a-user'
client = rados.Rados(rados_id=user,
                     clustername=name,
                     conffile=conf)
client.connect()
fsid = client.get_fsid()
if type(fsid) == str:
    print("value={} has correct type={}".format(fsid, type(fsid)))
else:
    print("value={} has incorrect type={} (expect str)".format(fsid, type(fsid)))
EOF

[Regression Potential]
This change ensures that cstr types are automatically decoded/encoded within the generated python bindings for the underlying system libraries.

If python code is blindly decoding the return values from the rados/rbd bindings, its possible this change will break such code paths; however the scoped changes in OpenStack detect the binary type and decode if needed.

This only really impacts any apps running under py3; py2 does lots of implicit conversation so is insulated from this bug.

-----------------------------------------------------------------------------

These fixes relate to issues we have found in Openstack [1][2] when running under Python 3. They are fixed upstream by commit [3] which is available in nautilus and beyond so we would like to backport to mimic and luminous.

[1] https://bugs.launchpad.net/nova/+bug/1816468
[2] https://bugs.launchpad.net/glance-store/+bug/1816721
[3] https://github.com/ceph/ceph/commit/c36d0f1a7de4668eb81075e4a94846cf81fc30cd

[James Page (james-page)]

Nautilus is stuck in eoan-proposed at the moment waiting for Ubuntu archive team review; once that's unblocked dev tasks can be marked fix committed.

[James Page (james-page)]

cosmic and disco both ship with mimic; luminous is also impacted but not in the context of OpenStack as releases prior to Rocky all run under Python 2, not Python 3.

[James Page (james-page)]

Actually this appears to not be in the nautilus release we have in eoan - picking the fix now.

[Edward Hope-Morley (hopem)]

The linked patch has actually been reverted upstream (my fault for not spotting that) and the following patch appears to be the one we actually want - https://github.com/ceph/ceph/commit/005f19eff0b4a92647e5847e306718be76704432

This new patch has a much narrower scope (just fixes get_fsid) but since that is the only problem we area currently observing I think its sufficient for requirements.

[James Page (james-page)]

The picked patch was reverted - this is the correct fix:

  https://github.com/ceph/ceph/commit/005f19eff0b4a92647e5847e306718be76704432

[James Page (james-page)]

This fix is included in the 13.2.6 release I'm currently working on so marking cosmic and disco tasks as invalid; this does not need a specific SRU

[James Page (james-page)]

bug 1831732 for 13.2.6

[Launchpad Janitor (janitor)]

This bug was fixed in the package ceph - 14.2.1-0ubuntu3

---------------
ceph (14.2.1-0ubuntu3) eoan; urgency=medium

  * d/p/pybind-auto-encode-decode-cstr.patch: Drop, reverted upstream.
  * d/p/fix-py3-encoding-fsid.patch: Cherry pick correct fix to resolve
    FSID encoding issues under Python 3 (LP: #1833079).

 -- James Page <email address hidden> Tue, 25 Jun 2019 08:02:09 +0100

[Chris MacNaughton (chris.macnaughton)]

Marking the cloud-archive tasks fix-released as the patch seems to be landed in the package branches for those releases.