Add support for systemd-networkd

When masking udev/systemd predictable network interface
names, the initramfs must be updated or the mask will not
be effective.

Add support for systemd-networkd using predictable network
interface names - can be extended using customisation scripts.

1 files changed, 105 insertions, 0 deletions

diff --git a/vmdebootstrap/network.py b/vmdebootstrap/network.py
new file mode 100644
index 0000000..740dede
--- /dev/null
+++ b/vmdebootstrap/network.py
@@ -0,0 +1,105 @@
+"""
+  Wrapper for network support
+"""
+# -*- coding: utf-8 -*-
+#
+#  network.py
+#  
+#  Copyright 2015 Neil Williams <codehelp@debian.org>
+#  
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#  
+#  This program 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 General Public License for more details.
+#  
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+#  MA 02110-1301, USA.
+#  
+#  
+
+import os
+from vmdebootstrap.base import (
+    Base,
+    runcmd,
+)
+
+# pylint: disable=missing-docstring
+
+
+class Networking(Base):
+
+    name = 'networking'
+
+    def _write_network_interfaces(self, rootdir, line):
+        self.message('Setting up networking')
+        ifc_d = os.path.join(rootdir, 'etc', 'network', 'interfaces.d')
+        ifc_file = os.path.join(rootdir, 'etc', 'network', 'interfaces')
+        with open(ifc_file, 'w') as netfile:
+            netfile.write(line)
+        if not os.path.exists(ifc_d):
+            os.mkdir(ifc_d)
+        with open(ethpath, 'w') as eth:
+            eth.write('auto lo\n')
+            eth.write('iface lo inet loopback\n')
+            if self.settings['enable-dhcp']:
+                eth.write('\n')
+                eth.write('auto eth0\n')
+                eth.write('iface eth0 inet dhcp\n')
+
+    def setup_wheezy_networking(self, rootdir):
+        """
+        unconditionally write for wheezy
+        (which became oldstable on 2015.04.25)
+        """
+        self._write_network_interfaces(
+            rootdir, 'source /etc/network/interfaces.d/*\n')
+
+    def setup_networking(self, rootdir):
+        self._write_network_interfaces(
+            rootdir, 'source-directory /etc/network/interfaces.d\n')
+
+    def systemd_support(self, rootdir):
+        """
+        Handle the systemd-networkd setting
+        """
+        if self.settings['systemd-networkd']:
+            self.enable_systemd_networkd(rootdir)
+        else:
+            self.mask_udev_predictable_rules(rootdir)
+
+    def mask_udev_predictable_rules(self, rootdir):
+        """
+        This can be reset later but to get networking using eth0
+        immediately upon boot, the interface we're going to use must
+        be known and must update the initramfs after setting up the
+        mask.
+        """
+        self.message('Disabling systemd predictable interface names')
+        udev_path = os.path.join(
+            'etc', 'udev', 'rules.d', '80-net-setup-link.rules')
+        runcmd(['chroot', rootdir, 'ln', '-s', '/dev/null', udev_path])
+
+    def enable_systemd_networkd(self, rootdir):
+        """
+        Get networking working immediately on boot, allow any en* interface
+        to be enabled by systemd-networkd using DHCP
+        https://coreos.com/os/docs/latest/network-config-with-networkd.html
+        http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
+        """
+        if not self.settings['enable-dhcp']:
+            return
+        self.message('Enabling systemd-networkd for DHCP')
+        ethpath = os.path.join(rootdir, 'etc', 'systemd', 'network', '99-dhcp.network')
+        with open(ethpath, 'w') as eth:
+            eth.write('[Match]\n')
+            eth.write('Name=en*\n')
+            eth.write('\n[Network]\n')
+            eth.write('DHCP=yes\n')
+        runcmd(['chroot', rootdir, 'systemctl', 'enable', 'systemd-networkd'])