Rename virt driver from 'docker' to 'zun'

The rationals are as following:
* Make it clear that the in-tree virt driver is not the same as the
  nova-docker driver
* Justify that Zun is going to support additional runtime
* Avoid name collision with nova-docker on packaging.

Change-Id: I08f9cc0100837f62c57e2e77cd7f6cd727b91b69
Closes-Bug: #1652387

devstack/lib/nova

@@ -27,7 +27,7 @@ NOVA_CONF=${NOVA_CONF:-NOVA_CONF_DIR/nova.conf}
 
 # configure_nova_docker - Set config files, create data dirs, etc
 function configure_nova_docker {
-    iniset $NOVA_CONF DEFAULT compute_driver docker.DockerDriver
+    iniset $NOVA_CONF DEFAULT compute_driver zun.DockerDriver
 
     # CentOS/RedHat distros don't start the services just after the package
     # is installed if it is not explicitily set. So the script fails on

devstack/override-defaults

@@ -3,5 +3,5 @@
 ZUN_DRIVER=${ZUN_DRIVER:-docker}
 
 if [[ ${ZUN_DRIVER} == "nova-docker" ]]; then
-    export VIRT_DRIVER=docker
+    export VIRT_DRIVER=zun
 fi

nova/virt/zun/__init__.py

@@ -17,6 +17,6 @@
 :mod:`docker` -- Nova support for Docker Hypervisor to run Linux containers
 ===========================================================================
 """
-from nova.virt.docker import driver
+from nova.virt.zun import driver
 
 DockerDriver = driver.DockerDriver

nova/virt/zun/driver.py

@@ -43,14 +43,15 @@ from nova.i18n import _LW
 from nova import objects
 from nova.objects import fields
 from nova import utils
-from nova.virt.docker import client as docker_client
-from nova.virt.docker import hostinfo
-from nova.virt.docker import network
 from nova.virt import driver
 from nova.virt import firewall
 from nova.virt import hardware
 from nova.virt import hostutils
 from nova.virt import images
+from nova.virt.zun import client as docker_client
+from nova.virt.zun import hostinfo
+from nova.virt.zun import network
+
 
 CONF = cfg.CONF
 CONF.import_opt('instances_path', 'nova.compute.manager')
@@ -76,7 +77,7 @@ docker_opts = [
                help='Location of TLS private key file for '
                     'securing docker api requests (tlskey).'),
     cfg.StrOpt('vif_driver',
-               default='nova.virt.docker.vifs.DockerGenericVIFDriver'),
+               default='nova.virt.zun.vifs.DockerGenericVIFDriver'),
     cfg.StrOpt('snapshots_directory',
                default='$instances_path/snapshots',
                help='Location where docker driver will temporarily store '

nova/virt/zun/vifs.py

@@ -28,7 +28,7 @@ from nova.network import manager
 from nova.network import model as network_model
 from nova.network import os_vif_util
 from nova import utils
-from nova.virt.docker import network
+from nova.virt.zun import network
 from oslo_config import cfg
 
 # We need config opts from manager, but pep8 complains, this silences it.