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