furnace/cli.py: add command line interface to furnace

furnace/cli.py

@@ -0,0 +1,125 @@
+#
+# Copyright (c) 2016-2018 Balabit
+#
+# This file is part of Furnace.
+#
+# Furnace is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 2.1 of the License, or
+# (at your option) any later version.
+#
+# Furnace is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with Furnace.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import argparse
+import sys
+import tempfile
+from pathlib import Path
+
+from . import version
+from .config import BindMount
+from .context import ContainerContext
+from .utils import OverlayfsMountContext
+
+
+DESCRIPTION = "A lightweight pure-python container implementation."
+
+
+def parse_arguments(argv):
+    parser = argparse.ArgumentParser(description=DESCRIPTION)
+    parser.add_argument(
+        'root_dir',
+        help="This directory will be the root directory of the container"
+    )
+    parser.add_argument(
+        'cmd',
+        nargs='?',
+        type=lambda cmd: [cmd],
+        help="this command that will be run. If it is empty, than furnace will give an interactive shell"
+    )
+    parser.add_argument(
+        'args',
+        nargs='*',
+        metavar='arg',
+        help="the arguments of the given command"
+    )
+    parser.add_argument(
+        '--version',
+        action='version',
+        version='%(prog)s {version}'.format(version=version.get_version()),
+    )
+    parser.add_argument(
+        '--hostname',
+        default='container',
+        help="virtual hostname setting for interactive shell"
+    )
+    parser.add_argument(
+        '-i', '--isolate-networking',
+        action='store_true',
+        help="create an isolated networking namespace for the container"
+    )
+    parser.add_argument(
+        '-p', '--persistent',
+        action='store_true',
+        help="do not create a temporary overlay on top of the root directory, the changes will be persistent"
+    )
+    parser.add_argument(
+        '-v', '--volume',
+        action='append',
+        metavar='src:dst:{rw,ro}',
+        default=[],
+        type=create_bind_from_string,
+        help="add volumes from the host machine to the container in the following format: "
+        "/source/from/the/host:/path/in/the/container:rw, (readonly mount is the default)"
+    )
+    return parser.parse_args(argv[1:])
+
+
+def create_bind_from_string(volume):
+    source, destination = volume.split(':', 1)
+    readonly = True
+    if ':' in destination:
+        destination, readwrite = destination.split(':', 1)
+        if readwrite == 'ro':
+            readonly = True
+        elif readwrite == 'rw':
+            readonly = False
+        else:
+            raise argparse.ArgumentError('For creating volumes use the "ro", "rw" labels.')
+
+    return BindMount(Path(source), Path(destination), readonly)
+
+
+def run_container(root_dir, bind_mounts, isolate_networking, hostname, cmd, args):
+    with ContainerContext(root_dir, isolate_networking=isolate_networking, bind_mounts=bind_mounts) as container:
+        if cmd:
+            container.run(cmd + args)
+        else:
+            container.interactive_shell(virtual_hostname=hostname)
+
+
+def main(argv=sys.argv):
+    args = parse_arguments(argv)
+    if args.persistent:
+        run_container(args.root_dir, args.volume, args.isolate_networking, args.hostname, args.cmd, args.args)
+    else:
+        with tempfile.TemporaryDirectory(
+            suffix="overlay_work"
+        ) as overlay_workdir, tempfile.TemporaryDirectory(
+            suffix="overlay_rw"
+        ) as overlay_rwdir, tempfile.TemporaryDirectory(
+            suffix="overlay_mount"
+        ) as overlay_mounted, OverlayfsMountContext(
+            [args.root_dir], overlay_rwdir, overlay_workdir, overlay_mounted
+        ):
+            run_container(overlay_mounted, args.volume, args.isolate_networking, args.hostname, args.cmd, args.args)
+
+
+if __name__ == '__main__':
+    sys.exit(main())

setup.py

@@ -51,6 +51,9 @@
         'Topic :: System',
     ],
     packages=find_packages(include=["furnace*"]),
+    entry_points={
+        'console_scripts': ['furnace=furnace.cli:main'],
+    },
     extras_require={
         'dev': dev_requirements
     },