Added implementation for custom image.

Two new commandline options are added: image and default-user. When
image parameter has been add there are implications that:

- default-user is also provided by commandline - regardless it is
  already present in yaml config
- distro parameter is ignored
- custom username, which might be provided by yaml file will become
  default-user if absent.

All of that is the consequence, that by providing custom qcow2 image
there is no easy way to determine what operating system is passed by,
therefore it is purely declarative way of creating VM with such image.

README.rst

@@ -55,7 +55,7 @@ or simply link it somewhere in the path:
    $ chmod +x ~/bin/boxpy
 
 and now you can issue some command. For example, to spin up a VM with Ubuntu
-18.04 with one CPU, 2GB of memory and 10GB of disk:
+18.04 with one CPU, 1GB of memory and 6GB of disk:
 
 .. code:: shell-session
 

box.py

@@ -46,9 +46,9 @@ ssh:
   emit_keys_to_console: false
 boxpy_data:
   cpus: 1
-  disk_size: 10240
+  disk_size: 6144
   key: ~/.ssh/id_rsa
-  memory: 2048
+  memory: 1024
 '''
 COMPLETIONS = {'bash': '''\
 _boxpy() {
@@ -138,9 +138,9 @@ _boxpy() {
             fi
             ;;
         create|rebuild)
-            items=(--cpus --disable-nested --disk-size --distro --forwarding
-                --image --key --memory --hostname --port --config --version
-                --type)
+            items=(--cpus --disable-nested --disk-size --default-user --distro
+                --forwarding --image --key --memory --hostname --port --config
+                --version --type)
             if [[ ${prev} == ${cmd} ]]; then
                 if [[ ${cmd} = "rebuild" ]]; then
                     _vms_comp vms
@@ -419,6 +419,10 @@ class Config:
                 continue
             setattr(self, attr, str(val))
 
+        # sort out case, where there is image/default-user provided
+        if self.image:
+            self._update_distros_with_custom_image()
+
         # set distribution and version if not specified by user
         if not self.distro:
             self.distro = 'ubuntu'
@@ -552,16 +556,6 @@ class Config:
                 continue
             setattr(self, key, str(val))
 
-        # update distros dict with custom entry if there is at least image
-        if conf.get('boxpy_data') and conf['boxpy_data'].get('image'):
-            custom = {'username': conf['boxpy_data'].get('default_user'),
-                      'realname': 'custom os',
-                      'img_class': CustomImage,
-                      'amd64': 'x86_64',
-                      'image': conf['boxpy_data']['image'],
-                      'default_version': '0'}
-            DISTROS['custom'] = custom
-
         # remove boxpy_data since it will be not needed on the guest side
         if conf.get('boxpy_data'):
             if conf['boxpy_data'].get('advanced'):
@@ -570,6 +564,18 @@ class Config:
 
         self._conf = conf
 
+    def _update_distros_with_custom_image(self):
+        self.image = os.path.abspath(self.image)
+        self.distro = 'custom'
+        if not self.username:
+            self.username = self.default_user
+        DISTROS['custom'] = {'username': self.default_user,
+                             'realname': 'custom os',
+                             'img_class': CustomImage,
+                             'amd64': 'x86_64',
+                             'image': self.image,
+                             'default_version': '0'}
+
     def _update(self, source, update):
         for key, val in update.items():
             if isinstance(val, collections.abc.Mapping):
@@ -1192,7 +1198,7 @@ def vmcreate(args, conf=None):
     if not vbox.create_controller('SATA', 'sata'):
         return 4
 
-    for key in ('distro', 'hostname', 'key', 'version', 'image'):
+    for key in ('distro', 'hostname', 'key', 'version', 'image', 'username'):
         if getattr(conf, key) is None:
             continue
         if not vbox.setextradata(key, getattr(conf, key)):
@@ -1526,10 +1532,16 @@ def main():
                         help="Alternative user-data template filepath")
     create.add_argument('-d', '--distro', help="Image name. 'ubuntu' is "
                         "default")
+    create.add_argument('-e', '--default-user', help="Default cloud-init user "
+                        "to be used with custom image (--image param). "
+                        "Without image it will make no effect.")
     create.add_argument('-f', '--forwarding', action='append', help="expose "
                         "port from VM to the host. It should be in format "
                         "'hostport:vmport'. this option can be used multiple "
                         "times for multiple ports.")
+    create.add_argument('-i', '--image', help="custom qcow2 image filepath. "
+                        "Note, that it requires to provide --default-user as "
+                        "well.")
     create.add_argument('-k', '--key', help="SSH key to be add to the config "
                         "drive. Default ~/.ssh/id_rsa")
     create.add_argument('-m', '--memory', help="amount of memory in "
@@ -1571,10 +1583,16 @@ def main():
     rebuild.add_argument('-c', '--config',
                          help="Alternative user-data template filepath")
     rebuild.add_argument('-d', '--distro', help="Image name.")
+    rebuild.add_argument('-e', '--default-user', help="Default cloud-init "
+                         "user to be used with custom image (--image param). "
+                         "Without image it will make no effect.")
     rebuild.add_argument('-f', '--forwarding', action='append', help="expose "
                          "port from VM to the host. It should be in format "
                          "'hostport:vmport'. this option can be used multiple "
                          "times for multiple ports.")
+    rebuild.add_argument('-i', '--image', help="custom qcow2 image filepath. "
+                         "Note, that it requires to provide --default-user as "
+                         "well.")
     rebuild.add_argument('-k', '--key',
                          help='SSH key to be add to the config drive')
     rebuild.add_argument('-m', '--memory', help='amount of memory in '
@@ -1617,6 +1635,10 @@ def main():
 
     args = parser.parse_args()
 
+    if 'image' in args and 'default_user' not in args:
+        parser.error('Parameter --image requires --default-user')
+        return 22
+
     LOG.set_verbose(args.verbose, args.quiet)
 
     if 'func' not in args and args.version: