Merge lp:~jtv/maas/net-udev-rules into lp:~maas-committers/maas/trunk

[Jeroen T. Vermeulen]

Generate udev rules file, server-side, for installation on a node.

Part of the work to generate a node's full networking configuration on the server, so Curtin can install it, with IPv6 optionally enabled and IPv4 optionally disabled.

This was largely just copied over from the node-side script that we currently install and run on a node to set up its networking. That script will go away once this new approach works.

Jeroen

[Raphaël Badin (rvb)]

Looks good.

review: Approve

=== modified file 'src/maasserver/networking_preseed.py'
--- src/maasserver/networking_preseed.py	2014-09-25 19:38:57 +0000
+++ src/maasserver/networking_preseed.py	2014-09-26 04:10:25 +0000
@@ -29,6 +29,7 @@
     ]
 
 from collections import defaultdict
+from textwrap import dedent
 
 from lxml import etree
 from maasserver.dns.zonegenerator import get_dns_server_address
@@ -369,3 +370,64 @@
                 compose_debian_network_interfaces_ipv6_stanza(
                     interface, static_ipv6, gateway))
     return '%s\n' % '\n\n'.join(stanzas)
+
+
+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 compose_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"
+
+    (Note the difference between `=` and `==`: they both occur.)
+    """
+    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
+
+
+def compose_linux_udev_rules_file(interfaces):
+    """Return text for a udev persistent-net rules file.
+
+    These rules assign fixed names to network interfaces.  They ensure that
+    the same network interface cards come up with the same interface names on
+    every boot.  Otherwise, the kernel may assign interface names in different
+    orders on every boot, and so network interfaces can "switch identities"
+    every other time the machine reboots.
+
+    :param interfaces: List of tuples of interface name and MAC address.
+    :return: Text to write into a udev rules file.
+    """
+    rules = [
+        compose_udev_rule(interface, mac)
+        for interface, mac in interfaces
+        ]
+    return dedent("""\
+        # MAAS-assigned network interface names.
+        %s
+        # End of MAAS-assigned network interface names.
+        """) % '\n\n'.join(rules)

=== modified file 'src/maasserver/tests/test_networking_preseed.py'
--- src/maasserver/tests/test_networking_preseed.py	2014-09-25 19:38:57 +0000
+++ src/maasserver/tests/test_networking_preseed.py	2014-09-26 04:10:25 +0000
@@ -31,6 +31,7 @@
     compose_debian_network_interfaces_file,
     compose_debian_network_interfaces_ipv4_stanza,
     compose_debian_network_interfaces_ipv6_stanza,
+    compose_linux_udev_rules_file,
     extract_mac_string,
     extract_network_interfaces,
     generate_dns_server_entry,
@@ -916,3 +917,17 @@
         interfaces_file = compose_debian_network_interfaces_file(node)
         self.assertIn('auto %s' % interface, interfaces_file)
         self.assertEqual(1, interfaces_file.count('auto %s' % interface))
+
+
+class TestComposeLinuxUdevRulesFile(MAASServerTestCase):
+
+    def test__generates_udev_rule(self):
+        interface = factory.make_name('eth')
+        mac = factory.make_mac_address()
+        expected_rule = (
+            '\nSUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", '
+            'ATTR{address}=="%(mac)s", NAME="%(interface)s"\n'
+            ) % {'mac': mac, 'interface': interface}
+        self.assertIn(
+            expected_rule,
+            compose_linux_udev_rules_file([(interface, mac)]))