support network configuration in cloud-init --local

this allows 'cloud-init --local' to fully run before networking comes up.
By doing so, we can now cleanly apply networking to the new system.

This adds support for reading ConfigDrive network configuration
and also from NoCloud.  The support is only present for ubuntu/debian
at the current time.  Other distros will follow.

Also ability to specify network configuration on kernel command line
via either ip= or network-config=<base64>.

1 files changed, 54 insertions, 0 deletions

diff --git a/cloudinit/net/udev.py b/cloudinit/net/udev.py
new file mode 100644
index 00000000..6435ace0
--- /dev/null
+++ b/cloudinit/net/udev.py
@@ -0,0 +1,54 @@
+#   Copyright (C) 2015 Canonical Ltd.
+#
+#   Author: Ryan Harper <ryan.harper@canonical.com>
+#
+#   Curtin is free software: you can redistribute it and/or modify it under
+#   the terms of the GNU Affero General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   Curtin 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 Affero General Public License for
+#   more details.
+#
+#   You should have received a copy of the GNU Affero General Public License
+#   along with Curtin.  If not, see <http://www.gnu.org/licenses/>.
+
+
+def compose_udev_equality(key, value):
+    """Return a udev comparison clause, like `ACTION=="add"`."""
+    assert key == key.upper()
+    return '%s=="%s"' % (key, value)
+
+
+def compose_udev_attr_equality(attribute, value):
+    """Return a udev attribute comparison clause, like `ATTR{type}=="1"`."""
+    assert attribute == attribute.lower()
+    return 'ATTR{%s}=="%s"' % (attribute, value)
+
+
+def compose_udev_setting(key, value):
+    """Return a udev assignment clause, like `NAME="eth0"`."""
+    assert key == key.upper()
+    return '%s="%s"' % (key, value)
+
+
+def generate_udev_rule(interface, mac):
+    """Return a udev rule to set the name of network interface with `mac`.
+
+    The rule ends up as a single line looking something like:
+
+    SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*",
+    ATTR{address}="ff:ee:dd:cc:bb:aa", NAME="eth0"
+    """
+    rule = ', '.join([
+        compose_udev_equality('SUBSYSTEM', 'net'),
+        compose_udev_equality('ACTION', 'add'),
+        compose_udev_equality('DRIVERS', '?*'),
+        compose_udev_attr_equality('address', mac),
+        compose_udev_setting('NAME', interface),
+        ])
+    return '%s\n' % rule
+
+# vi: ts=4 expandtab syntax=python