ceph-iscsi on Ubuntu / no attribute cluster

Trying to get it running on Ubuntu 19.10 / Eoan.

gw service is running but the api makes some problems:

```
server03 /opt/ceph-iscsi # /usr/bin/rbd-target-api
Traceback (most recent call last):
File "/usr/bin/rbd-target-api", line 4, in
__import__('pkg_resources').run_script('ceph-iscsi==3.3', 'rbd-target-api')
File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 666, in run_script
self.require(requires)[0].run_script(script_name, ns)
File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 1469, in run_script
exec(script_code, namespace, namespace)
File "/usr/local/lib/python3.7/dist-packages/ceph_iscsi-3.3-py3.7.egg/EGG-INFO/scripts/rbd-target-api", line 2916, in
File "/usr/local/lib/python3.7/dist-packages/ceph_iscsi-3.3-py3.7.egg/ceph_iscsi_config/common.py", line 80, in __init__
File "/usr/local/lib/python3.7/dist-packages/ceph_iscsi-3.3-py3.7.egg/ceph_iscsi_config/common.py", line 34, in __init__
File "rados.pyx", line 625, in rados.Rados.__init__
File "rados.pyx", line 516, in rados.requires.wrapper.validate_func
File "rados.pyx", line 665, in rados.Rados.__setup
rados.Error: rados_initialize failed with error code: -22
Exception ignored in:
Traceback (most recent call last):
File "/usr/local/lib/python3.7/dist-packages/ceph_iscsi-3.3-py3.7.egg/ceph_iscsi_config/common.py", line 42, in __del__
AttributeError: 'CephCluster' object has no attribute 'cluster'
```

Install Log:

```
server03 /opt/ceph-iscsi # python3 setup.py install --install-scripts=/usr/bin
running install
running bdist_egg
running egg_info
writing ceph_iscsi.egg-info/PKG-INFO
writing dependency_links to ceph_iscsi.egg-info/dependency_links.txt
writing top-level names to ceph_iscsi.egg-info/top_level.txt
reading manifest file 'ceph_iscsi.egg-info/SOURCES.txt'
writing manifest file 'ceph_iscsi.egg-info/SOURCES.txt'
installing library code to build/bdist.linux-x86_64/egg
running install_lib
running build_py
creating build/bdist.linux-x86_64/egg
creating build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/gateway_object.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/group.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/settings.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/common.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/target.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/client.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/lio.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/alua.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/__init__.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/backstore.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/discovery.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/gateway.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/metrics.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/utils.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/lun.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
copying build/lib/ceph_iscsi_config/gateway_setting.py -> build/bdist.linux-x86_64/egg/ceph_iscsi_config
creating build/bdist.linux-x86_64/egg/gwcli
copying build/lib/gwcli/ceph.py -> build/bdist.linux-x86_64/egg/gwcli
copying build/lib/gwcli/client.py -> build/bdist.linux-x86_64/egg/gwcli
copying build/lib/gwcli/node.py -> build/bdist.linux-x86_64/egg/gwcli
copying build/lib/gwcli/__init__.py -> build/bdist.linux-x86_64/egg/gwcli
copying build/lib/gwcli/storage.py -> build/bdist.linux-x86_64/egg/gwcli
copying build/lib/gwcli/gateway.py -> build/bdist.linux-x86_64/egg/gwcli
copying build/lib/gwcli/utils.py -> build/bdist.linux-x86_64/egg/gwcli
copying build/lib/gwcli/hostgroup.py -> build/bdist.linux-x86_64/egg/gwcli
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/gateway_object.py to gateway_object.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/group.py to group.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/settings.py to settings.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/common.py to common.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/target.py to target.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/client.py to client.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/lio.py to lio.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/alua.py to alua.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/__init__.py to __init__.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/backstore.py to backstore.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/discovery.py to discovery.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/gateway.py to gateway.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/metrics.py to metrics.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/utils.py to utils.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/lun.py to lun.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/ceph_iscsi_config/gateway_setting.py to gateway_setting.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/gwcli/ceph.py to ceph.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/gwcli/client.py to client.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/gwcli/node.py to node.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/gwcli/__init__.py to __init__.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/gwcli/storage.py to storage.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/gwcli/gateway.py to gateway.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/gwcli/utils.py to utils.cpython-37.pyc
byte-compiling build/bdist.linux-x86_64/egg/gwcli/hostgroup.py to hostgroup.cpython-37.pyc
installing package data to build/bdist.linux-x86_64/egg
running install_data
creating build/bdist.linux-x86_64/egg/EGG-INFO
installing scripts to build/bdist.linux-x86_64/egg/EGG-INFO/scripts
running install_scripts
running build_scripts
creating build/bdist.linux-x86_64/egg/EGG-INFO/scripts
copying build/scripts-3.7/rbd-target-gw.py -> build/bdist.linux-x86_64/egg/EGG-INFO/scripts
copying build/scripts-3.7/rbd-target-api.py -> build/bdist.linux-x86_64/egg/EGG-INFO/scripts
copying build/scripts-3.7/gwcli.py -> build/bdist.linux-x86_64/egg/EGG-INFO/scripts
changing mode of build/bdist.linux-x86_64/egg/EGG-INFO/scripts/rbd-target-gw.py to 755
changing mode of build/bdist.linux-x86_64/egg/EGG-INFO/scripts/rbd-target-api.py to 755
changing mode of build/bdist.linux-x86_64/egg/EGG-INFO/scripts/gwcli.py to 755
copying ceph_iscsi.egg-info/PKG-INFO -> build/bdist.linux-x86_64/egg/EGG-INFO
copying ceph_iscsi.egg-info/SOURCES.txt -> build/bdist.linux-x86_64/egg/EGG-INFO
copying ceph_iscsi.egg-info/dependency_links.txt -> build/bdist.linux-x86_64/egg/EGG-INFO
copying ceph_iscsi.egg-info/top_level.txt -> build/bdist.linux-x86_64/egg/EGG-INFO
zip_safe flag not set; analyzing archive contents...
creating 'dist/ceph_iscsi-3.3-py3.7.egg' and adding 'build/bdist.linux-x86_64/egg' to it
removing 'build/bdist.linux-x86_64/egg' (and everything under it)
Processing ceph_iscsi-3.3-py3.7.egg
Removing /usr/local/lib/python3.7/dist-packages/ceph_iscsi-3.3-py3.7.egg
Copying ceph_iscsi-3.3-py3.7.egg to /usr/local/lib/python3.7/dist-packages
ceph-iscsi 3.3 is already the active version in easy-install.pth
Installing gwcli script to /usr/bin
Installing rbd-target-api script to /usr/bin
Installing rbd-target-gw script to /usr/bin

Installed /usr/local/lib/python3.7/dist-packages/ceph_iscsi-3.3-py3.7.egg
Processing dependencies for ceph-iscsi==3.3
Finished processing dependencies for ceph-iscsi==3.3
```

Start with the rbd-target-api traceback and ceph_iscsi_config/common.py, especially the CephCluster initialization and cleanup paths. Reproduce the failure on Ubuntu 19.10 with the reported installation, identify the cause of rados initialization failure, and verify that the API starts without the follow-on AttributeError.

Written by the indexing model from the issue text.