diff --git a/usr/bin/spoc-app b/usr/bin/spoc-app
index 6085771..7b23d97 100644
--- a/usr/bin/spoc-app
+++ b/usr/bin/spoc-app
@@ -7,16 +7,6 @@ import os
 from spoc import publisher
 from spoc.cli import readable_size
 
-ACTION_LIST = 1
-ACTION_INSTALL = 2
-ACTION_UPGRADE = 3
-ACTION_UNINSTALL = 4
-ACTION_START = 5
-ACTION_STOP = 6
-ACTION_STATUS = 7
-ACTION_PUBLISH = 8
-ACTION_UNPUBLISH = 9
-
 def listing():
     raise NotImplementedException()
 
@@ -61,61 +51,61 @@ parser.set_defaults(action=None)
 subparsers = parser.add_subparsers()
 
 parser_list = subparsers.add_parser('list')
-parser_list.set_defaults(action=ACTION_LIST)
+parser_list.set_defaults(action=listing)
 parser_list.add_argument('type', choices=('installed', 'online', 'upgrades', 'published'), default='installed', const='installed', nargs='?')
 
 parser_install = subparsers.add_parser('install')
-parser_install.set_defaults(action=ACTION_INSTALL)
+parser_install.set_defaults(action=install)
 parser_install.add_argument('app')
 
 parser_upgrade = subparsers.add_parser('upgrade')
-parser_upgrade.set_defaults(action=ACTION_UPGRADE)
+parser_upgrade.set_defaults(action=upgrade)
 parser_upgrade.add_argument('app')
 
 parser_uninstall = subparsers.add_parser('uninstall')
-parser_uninstall.set_defaults(action=ACTION_UNINSTALL)
+parser_uninstall.set_defaults(action=uninstall)
 parser_uninstall.add_argument('app')
 
 parser_start = subparsers.add_parser('start')
-parser_start.set_defaults(action=ACTION_START)
+parser_start.set_defaults(action=start)
 parser_start.add_argument('app')
 
 parser_stop = subparsers.add_parser('stop')
-parser_stop.set_defaults(action=ACTION_STOP)
+parser_stop.set_defaults(action=stop)
 parser_stop.add_argument('app')
 
 parser_status = subparsers.add_parser('status')
-parser_status.set_defaults(action=ACTION_STATUS)
+parser_status.set_defaults(action=status)
 parser_status.add_argument('app')
 
 parser_publish = subparsers.add_parser('publish')
-parser_publish.set_defaults(action=ACTION_PUBLISH)
+parser_publish.set_defaults(action=publish)
 parser_publish.add_argument('-f', '--force', action='store_true', help='Force republish already published application')
 parser_publish.add_argument('file')
 
 parser_unpublish = subparsers.add_parser('unpublish')
-parser_unpublish.set_defaults(action=ACTION_UNPUBLISH)
+parser_unpublish.set_defaults(action=unpublish)
 parser_unpublish.add_argument('app')
 
 args = parser.parse_args()
 
-if args.action == ACTION_LIST:
+if args.action is listing:
     listing(args.type)
-elif args.action == ACTION_INSTALL:
+elif args.action is install:
     install(args.app)
-elif args.action == ACTION_UPGRADE:
+elif args.action is upgrade:
     upgrade(args.app)
-elif args.action == ACTION_UNINSTALL:
+elif args.action is uninstall:
     uninstall(args.app)
-elif args.action == ACTION_START:
+elif args.action is start:
     start(args.app)
-elif args.action == ACTION_STOP:
+elif args.action is stop:
     stop(args.app)
-elif args.action == ACTION_STATUS:
+elif args.action is status:
     status(args.app)
-elif args.action == ACTION_PUBLISH:
+elif args.action is publish:
     publish(args.file, args.force)
-elif args.action == ACTION_UNPUBLISH:
+elif args.action is unpublish:
     unpublish(args.app)
 else:
     parser.print_usage()
diff --git a/usr/bin/spoc-container b/usr/bin/spoc-container
index da58d7c..a4d2c8a 100644
--- a/usr/bin/spoc-container
+++ b/usr/bin/spoc-container
@@ -10,15 +10,6 @@ from spoc.container import Container, STATE_RUNNING, STATE_STOPPED
 from spoc.image import Image
 from spoc.config import VOLUME_DIR
 
-ACTION_LIST = 1
-ACTION_CREATE = 2
-ACTION_MODIFY = 3
-ACTION_DESTROY = 4
-ACTION_START = 5
-ACTION_STOP = 6
-ACTION_STATUS = 7
-ACTION_EXEC = 8
-
 def listing(state):
     if state == 'all':
         containers = repo_local.get_containers().keys()
@@ -115,11 +106,11 @@ parser.set_defaults(action=None)
 subparsers = parser.add_subparsers()
 
 parser_list = subparsers.add_parser('list')
-parser_list.set_defaults(action=ACTION_LIST)
+parser_list.set_defaults(action=listing)
 parser_list.add_argument('type', choices=('all', 'running', 'stopped'), default='all', const='all', nargs='?')
 
 parser_create = subparsers.add_parser('create')
-parser_create.set_defaults(action=ACTION_CREATE)
+parser_create.set_defaults(action=create)
 parser_create.add_argument('-d', '--depends', action='append', default=[], help='Add another container as a start dependency')
 parser_create.add_argument('-m', '--mount', action='append', default=[], help='Add mount to the container - format volume:mountpoint')
 parser_create.add_argument('-e', '--env', action='append', default=[], help='Add environment variable for the container - format KEY=value')
@@ -134,7 +125,7 @@ parser_create.add_argument('container')
 parser_create.add_argument('image')
 
 parser_modify = subparsers.add_parser('modify')
-parser_modify.set_defaults(action=ACTION_MODIFY)
+parser_modify.set_defaults(action=modify)
 parser_modify.add_argument('-d', '--depends', action='append', default=[], help='Add another container as a start dependency - prepend the name with ! to remove the dependency')
 parser_modify.add_argument('-m', '--mount', action='append', default=[], help='Add mount to the container - format volume:mountpoint - specify empty mountpoint to remove the mount')
 parser_modify.add_argument('-e', '--env', action='append', default=[], help='Add environment variable for the container - format KEY=value - specify empty value to remove the env')
@@ -148,23 +139,23 @@ parser_modify.add_argument('-a', '--autostart', choices=('on', 'off'), help='Set
 parser_modify.add_argument('container')
 
 parser_destroy = subparsers.add_parser('destroy')
-parser_destroy.set_defaults(action=ACTION_DESTROY)
+parser_destroy.set_defaults(action=destroy)
 parser_destroy.add_argument('container')
 
 parser_start = subparsers.add_parser('start')
-parser_start.set_defaults(action=ACTION_START)
+parser_start.set_defaults(action=start)
 parser_start.add_argument('container')
 
 parser_stop = subparsers.add_parser('stop')
-parser_stop.set_defaults(action=ACTION_STOP)
+parser_stop.set_defaults(action=stop)
 parser_stop.add_argument('container')
 
 parser_status = subparsers.add_parser('status')
-parser_status.set_defaults(action=ACTION_STATUS)
+parser_status.set_defaults(action=status)
 parser_status.add_argument('container')
 
 parser_exec = subparsers.add_parser('exec')
-parser_exec.set_defaults(action=ACTION_EXEC)
+parser_exec.set_defaults(action=execute)
 parser_exec.add_argument('-u', '--uid', help='Sets the command UID')
 parser_exec.add_argument('-g', '--gid', help='Sets the command GID')
 parser_exec.add_argument('container')
@@ -172,21 +163,21 @@ parser_exec.add_argument('command', nargs=argparse.REMAINDER)
 
 args = parser.parse_args()
 
-if args.action == ACTION_LIST:
+if args.action is listing:
     listing(args.type)
-elif args.action == ACTION_CREATE:
+elif args.action is create:
     create(args.container, args.image, args.depends, args.mount, args.env, args.uid, args.gid, args.cmd, args.workdir, args.ready, args.stopsig, args.autostart)
-elif args.action == ACTION_MODIFY:
+elif args.action is modify:
     modify(args.container, args.depends, args.mount, args.env, args.uid, args.gid, args.cmd, args.workdir, args.ready, args.stopsig, args.autostart)
-elif args.action == ACTION_DESTROY:
+elif args.action is destroy:
     destroy(args.container)
-elif args.action == ACTION_START:
+elif args.action is start:
     start(args.container)
-elif args.action == ACTION_STOP:
+elif args.action is stop:
     stop(args.container)
-elif args.action == ACTION_STATUS:
+elif args.action is status:
     status(args.container)
-elif args.action == ACTION_EXEC:
+elif args.action is execute:
     execute(args.container, args.command, args.uid, args.gid)
 else:
     parser.print_usage()
diff --git a/usr/bin/spoc-image b/usr/bin/spoc-image
index b092e73..7013b27 100644
--- a/usr/bin/spoc-image
+++ b/usr/bin/spoc-image
@@ -13,14 +13,6 @@ from spoc.image import Image
 from spoc.imagebuilder import ImageBuilder
 from spoc.cli import ActionQueue, readable_size
 
-ACTION_LIST = 1
-ACTION_DOWNLOAD = 2
-ACTION_DELETE = 3
-ACTION_CLEAN = 4
-ACTION_BUILD = 5
-ACTION_PUBLISH = 6
-ACTION_UNPUBLISH = 7
-
 def get_image_name(file_path):
     # Read and return image name from image file
     with open(file_path) as f:
@@ -116,50 +108,50 @@ parser.set_defaults(action=None)
 subparsers = parser.add_subparsers()
 
 parser_list = subparsers.add_parser('list')
-parser_list.set_defaults(action=ACTION_LIST)
+parser_list.set_defaults(action=listing)
 parser_list.add_argument('type', choices=('installed', 'online', 'published'), default='installed', const='installed', nargs='?')
 
 parser_download = subparsers.add_parser('download')
-parser_download.set_defaults(action=ACTION_DOWNLOAD)
+parser_download.set_defaults(action=download)
 parser_download.add_argument('image')
 
 parser_delete = subparsers.add_parser('delete')
-parser_delete.set_defaults(action=ACTION_DELETE)
+parser_delete.set_defaults(action=delete)
 parser_delete.add_argument('image')
 
 parser_clean = subparsers.add_parser('clean')
-parser_clean.set_defaults(action=ACTION_CLEAN)
+parser_clean.set_defaults(action=clean)
 
 parser_build = subparsers.add_parser('build')
-parser_build.set_defaults(action=ACTION_BUILD)
+parser_build.set_defaults(action=build)
 parser_build.add_argument('-f', '--force', action='store_true', help='Force rebuild already existing image')
 parser_build.add_argument('-p', '--publish', action='store_true', help='Publish the image after successful build')
 parser_build.add_argument('file')
 
 parser_publish = subparsers.add_parser('publish')
-parser_publish.set_defaults(action=ACTION_PUBLISH)
+parser_publish.set_defaults(action=publish)
 parser_publish.add_argument('-f', '--force', action='store_true', help='Force republish already published image')
 parser_publish.add_argument('image')
 
 parser_unpublish = subparsers.add_parser('unpublish')
-parser_unpublish.set_defaults(action=ACTION_UNPUBLISH)
+parser_unpublish.set_defaults(action=unpublish)
 parser_unpublish.add_argument('image')
 
 args = parser.parse_args()
 
-if args.action == ACTION_LIST:
+if args.action is listing:
     listing(args.type)
-elif args.action == ACTION_DOWNLOAD:
+elif args.action is download:
     download(args.image)
-elif args.action == ACTION_DELETE:
+elif args.action is delete:
     delete(args.image)
-elif args.action == ACTION_CLEAN:
+elif args.action is clean:
     clean()
-elif args.action == ACTION_BUILD:
+elif args.action is build:
     build(args.file, args.force, args.publish)
-elif args.action == ACTION_PUBLISH:
+elif args.action is publish:
     publish(args.image, args.force)
-elif args.action == ACTION_UNPUBLISH:
+elif args.action is unpublish:
     unpublish(args.image)
 else:
     parser.print_usage()
diff --git a/usr/lib/python3.8/spoc/container.py b/usr/lib/python3.8/spoc/container.py
index e078b1a..f5581c2 100644
--- a/usr/lib/python3.8/spoc/container.py
+++ b/usr/lib/python3.8/spoc/container.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+import copy
 import os
 import shlex
 import shutil
@@ -56,11 +57,12 @@ class Container:
             setattr(self, key, definition[key])
 
     def get_definition(self):
+        # Return shallow copy of container definition as dictionary
         definition = {}
         for key in DEFINITION_MEMBERS:
             value = getattr(self, key)
             if value:
-                definition[key] = value
+                definition[key] = copy.copy(value)
         return definition
 
     def get_state(self):
diff --git a/usr/lib/python3.8/spoc/image.py b/usr/lib/python3.8/spoc/image.py
index 629b6db..74798c9 100644
--- a/usr/lib/python3.8/spoc/image.py
+++ b/usr/lib/python3.8/spoc/image.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+import copy
 import os
 import shutil
 import tarfile
@@ -35,11 +36,16 @@ class Image:
             setattr(self, key, definition[key])
 
     def get_definition(self, including_self_layer=False):
+        # Return shallow copy of image definition as dictionary
         definition = {}
         for key in DEFINITION_MEMBERS:
             value = getattr(self, key)
             if value:
-                definition[key] = value
+                definition[key] = copy.copy(value)
+        # Always add layers in definition even if there are none to ease processing elsewhere
+        if 'layers' not in definition:
+            definition['layers'] = []
+        # Add the image's layer as tompost, if requested (useful for container creation)
         if including_self_layer:
             definition['layers'].append(self.name)
         return definition
diff --git a/usr/lib/python3.8/spoc/imagebuilder.py b/usr/lib/python3.8/spoc/imagebuilder.py
index 9316bfc..3c0c658 100644
--- a/usr/lib/python3.8/spoc/imagebuilder.py
+++ b/usr/lib/python3.8/spoc/imagebuilder.py
@@ -42,7 +42,6 @@ class ImageBuilder:
         elif 'FROM' == directive:
             # Set the values of image from which this one inherits
             self.image.set_definition(Image(args).get_definition(True))
-            self.image.layers.append(self.image.name)
         elif 'COPY' == directive:
             srcdst = args.split()
             self.copy_files(srcdst[0], srcdst[1] if len(srcdst) > 1 else '')
@@ -99,7 +98,7 @@ class ImageBuilder:
         if not uid.isdigit() or not gid.isdigit():
             # Resolve the UID/GID from container if either of them is entered as string
             container = Container(self.image.name, False)
-            container.set_definition(self.image.get_definition())
+            container.set_definition(self.image.get_definition(True))
             container.create()
             uid,gid = container.get_uidgid(uid, gid)
             container.destroy()