Create lxchelper for prepare, cleanup and extract

usr/bin/lxchelper

@@ -0,0 +1,68 @@
+#!/usr/bin/python3
+# -*- coding: utf-8 -*-
+
+import argparse
+import os
+import shutil
+import sys
+import tempfile
+
+from lxcmgr import lxcmgr
+from lxcmgr.paths import LXC_ROOT
+
+def get_layers(container):
+    with open(os.path.join(LXC_ROOT, container, 'config')) as f:
+        for line in f.read().splitlines():
+            if line.startswith('lxc.hook.pre-start'):
+                return line.split()[-1].split(',')
+
+def copy(source, destination):
+    if os.path.isdir(source):
+        shutil.copytree(source, destination, True)
+    else:
+        shutil.copy2(source, destination)
+
+def extract(args):
+    with tempfile.TemporaryDirectory() as tmp_rootfs:
+        layers = get_layers(args.container)
+        lxcmgr.mount_rootfs(args.container, layers, tmp_rootfs)
+        source = os.path.join(tmp_rootfs, args.source.lstrip('/'))
+        try:
+            copy(source, args.destination)
+        except:
+            lxcmgr.unmount_rootfs(tmp_rootfs)
+            raise
+        lxcmgr.unmount_rootfs(tmp_rootfs)
+
+def main(args):
+    if args.action == 'prepare':
+        # Used with LXC hooks on container startup
+        lxcmgr.prepare_container(args.container, args.layers)
+    elif args.action == 'cleanup':
+        # Used with LXC hooks on container stop
+        lxcmgr.cleanup_container(args.container)
+    elif args.action == 'extract':
+        # Used in install.sh scripts to get files or directories from containers rootfs (excluding persistent mounts)
+        extract(args)
+
+parser = argparse.ArgumentParser(description='Collection of auxiliary LXC tools')
+subparsers = parser.add_subparsers()
+
+parser_prepare = subparsers.add_parser('prepare', help='Perform pre-start steps for LXC')
+parser_prepare.set_defaults(action='prepare')
+parser_prepare.add_argument('layers', help='OverlayFS LXC rootfs layers')
+parser_prepare.add_argument('container', help='Container name')
+parser_prepare.add_argument('lxc', nargs=argparse.REMAINDER)
+
+parser_cleanup = subparsers.add_parser('cleanup', help='Perform post-stop steps for LXC')
+parser_cleanup.set_defaults(action='cleanup')
+parser_cleanup.add_argument('container', help='Container name')
+parser_cleanup.add_argument('lxc', nargs=argparse.REMAINDER)
+
+parser_extract = subparsers.add_parser('extract', help='Extracts files or directories from containers rootfs (excluding persistent mounts)')
+parser_cleanup.set_defaults(action='extract')
+parser_extract.add_argument('container', help='Container name')
+parser_extract.add_argument('source', help='Source file or directory within the container')
+parser_extract.add_argument('destination', help='Destination file or directory on the host')
+
+main(parser.parse_args())

usr/bin/lxcmgr

@@ -10,44 +10,6 @@ from concurrent.futures import ThreadPoolExecutor
 from lxcmgr import lxcmgr
 from lxcmgr.pkgmgr import App, Stage, PkgMgr
 
-parser = argparse.ArgumentParser(description='LXC container and package manager')
-subparsers = parser.add_subparsers()
-
-parser_list = subparsers.add_parser('list')
-subparsers_list = parser_list.add_subparsers()
-parser_list_installed = subparsers_list.add_parser('installed')
-parser_list_installed.set_defaults(action='list-installed')
-parser_list_online = subparsers_list.add_parser('online')
-parser_list_online.set_defaults(action='list-online')
-parser_list_updates = subparsers_list.add_parser('updates')
-parser_list_updates.set_defaults(action='list-updates')
-
-parser_install = subparsers.add_parser('install')
-parser_install.set_defaults(action='install')
-parser_install.add_argument('app', help='Application to install')
-
-parser_update = subparsers.add_parser('update')
-parser_update.set_defaults(action='update')
-parser_update.add_argument('app', help='Application to update')
-
-parser_uninstall = subparsers.add_parser('uninstall')
-parser_uninstall.set_defaults(action='uninstall')
-parser_uninstall.add_argument('app', help='Application to uninstall')
-
-parser_container = subparsers.add_parser('container')
-subparsers_container = parser_container.add_subparsers()
-
-parser_container_prepare = subparsers_container.add_parser('prepare')
-parser_container_prepare.set_defaults(action='container-prepare')
-parser_container_prepare.add_argument('layers', help='OverlayFS LXC rootfs layers')
-parser_container_prepare.add_argument('container', help='Container name')
-parser_container_prepare.add_argument('lxc', nargs=argparse.REMAINDER)
-
-parser_container_cleanup = subparsers_container.add_parser('cleanup')
-parser_container_cleanup.set_defaults(action='container-cleanup')
-parser_container_cleanup.add_argument('container', help='Container name')
-parser_container_cleanup.add_argument('lxc', nargs=argparse.REMAINDER)
-
 def print_apps(packages):
     for app, meta in packages.items():
         print(app, meta['version'])
@@ -125,26 +87,42 @@ def uninstall_app(app):
     app = App(app)
     run_install_action(pm.uninstall_app, app)
 
-args = parser.parse_args()
+def main(args):
-if not hasattr(args, 'action'):
+    if args.action == 'list-installed':
-    parser.print_usage()
-    sys.exit(1)
-
-if args.action == 'list-installed':
         list_installed()
-elif args.action == 'list-online':
+    elif args.action == 'list-online':
         list_online()
-elif args.action == 'list-updates':
+    elif args.action == 'list-updates':
         list_updates()
-elif args.action == 'install':
+    elif args.action == 'install':
         install_app(args.app)
-elif args.action == 'update':
+    elif args.action == 'update':
         update_app(args.app)
-elif args.action == 'uninstall':
+    elif args.action == 'uninstall':
         uninstall_app(args.app)
-elif args.action == 'container-prepare':
+
-    # Used with LXC hooks on container startup
+parser = argparse.ArgumentParser(description='LXC container and package manager')
-    lxcmgr.prepare_container(args.container, args.layers)
+subparsers = parser.add_subparsers()
-elif args.action == 'container-cleanup':
+
-    # Used with LXC hooks on container stop
+parser_list = subparsers.add_parser('list')
-    lxcmgr.cleanup_container(args.container)
+subparsers_list = parser_list.add_subparsers()
+parser_list_installed = subparsers_list.add_parser('installed')
+parser_list_installed.set_defaults(action='list-installed')
+parser_list_online = subparsers_list.add_parser('online')
+parser_list_online.set_defaults(action='list-online')
+parser_list_updates = subparsers_list.add_parser('updates')
+parser_list_updates.set_defaults(action='list-updates')
+
+parser_install = subparsers.add_parser('install')
+parser_install.set_defaults(action='install')
+parser_install.add_argument('app', help='Application to install')
+
+parser_update = subparsers.add_parser('update')
+parser_update.set_defaults(action='update')
+parser_update.add_argument('app', help='Application to update')
+
+parser_uninstall = subparsers.add_parser('uninstall')
+parser_uninstall.set_defaults(action='uninstall')
+parser_uninstall.add_argument('app', help='Application to uninstall')
+
+main(parser.parse_args())

usr/lib/python3.6/lxcmgr/lxcmgr.py

@@ -16,14 +16,20 @@ def prepare_container(container, layers):
     # which don't have the capability to mount overlays - https://www.spinics.net/lists/linux-fsdevel/msg105877.html
     rootfs = os.path.join(LXC_ROOT, container, 'rootfs')
     # Unmount rootfs in case it remained mounted for whatever reason
-    subprocess.run(['umount', rootfs])
+    unmount_rootfs(rootfs)
     layers = layers.split(',')
+    mount_rootfs(container, layers, rootfs)
+
+def mount_rootfs(container, layers, mountpoint)
     if len(layers) == 1:
         # We have only single layer, no overlay needed
-        subprocess.run(['mount', '--bind', layers[0], rootfs])
+        subprocess.run(['mount', '--bind', layers[0], mountpoint])
     else:
         olwork = os.path.join(LXC_ROOT, container, 'olwork')
-        subprocess.run(['mount', '-t', 'overlay', '-o', 'upperdir={},lowerdir={},workdir={}'.format(layers[0], ':'.join(layers[1:]), olwork), 'none', rootfs])
+        subprocess.run(['mount', '-t', 'overlay', '-o', 'upperdir={},lowerdir={},workdir={}'.format(layers[0], ':'.join(layers[1:]), olwork), 'none', mountpoint])
+
+def unmount_rootfs(mountpoint):
+    subprocess.run(['umount', '--quiet', mountpoint])
 
 def clean_ephemeral_layer(container):
     # Cleans containers ephemeral layer. Called in lxc.hook.post-stop and lxc.hook.pre-start in case of unclean shutdown
@@ -35,7 +41,7 @@ def clean_ephemeral_layer(container):
 def cleanup_container(container):
     # Unmount rootfs
     rootfs = os.path.join(LXC_ROOT, container, 'rootfs')
-    subprocess.run(['umount', rootfs])
+    unmount_rootfs(rootfs)
     # Remove ephemeral layer data
     clean_ephemeral_layer(container)
 

usr/lib/python3.6/lxcmgr/templates.py

@@ -39,8 +39,8 @@ lxc.idmap = u 0 100000 65536
 lxc.idmap = g 0 100000 65536
 
 # Hooks
-lxc.hook.pre-start = /usr/bin/lxcmgr container prepare {layers}
+lxc.hook.pre-start = /usr/bin/lxchelper prepare {layers}
-lxc.hook.post-stop = /usr/bin/lxcmgr container cleanup
+lxc.hook.post-stop = /usr/bin/lxchelper cleanup
 
 # Other
 lxc.arch = linux64