When lio is configured for iscsi_helper things break due to usage of CONF (Juno)

[John Griffith]

In the base volume driver there's a check for iscsi_helper that then results in a call to initialize_connection that is intended to be for configurations using LIO iscsi_helper:
    https://github.com/openstack/cinder/blob/stable/juno/cinder/volume/driver.py#L1022

The problem is that this is using the global CONF instead of self.configuration, which means that every driver on the system will pick up this setting and attempt the initialize. This includes drivers that have their own target mechanism and don't use LIO or Tgt etc.

This is particularly problematic because RHEL based distributions have switched to using LIO as the default iscsi_helper and tools like packstack and foreman appear to configure this automatically. So if somebody attempts to configure a backend like SolidFire things like copy-image-to-volume will fail during the attach phase because the initialize_connection method is not implemented in those drivers.

This was fixed in Kilo during target rework, but we never went back and fixed it in Juno.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/juno
Review: https://review.openstack.org/183330

[OpenStack Infra (hudson-openstack)]

Change abandoned by John Griffith (<email address hidden>) on branch: stable/juno
Review: https://review.openstack.org/183330