Merge lp:~mpontillo/maas/fix-map-interfaces-by-mac-failure-with-bond-driver-loaded-1.8 into lp:maas/1.8

[Mike Pontillo]

Backport 4025: Make map_interfaces_by_mac() more robust by ignoring files in /sys/class/net (objects that do not represent interfaces are not directories)

MAAS 1.8 version of this MP:

https://code.launchpad.net/~mpontillo/maas/fix-map-interfaces-by-mac-failure-with-bond-driver-loaded/+merge/262154

The unit tests fail as follows when the bonding driver is loaded, and no bond interfaces are configured:

http://paste.ubuntu.com/11727748/

I'm not certain, but I think this may fail in production if the bonding driver is loaded. If so, this is a critical bug that should be backported to 1.8.

[Raphaël Badin (rvb)]

Generally, when you backport a fix to a stable branch:
a) make sure a critical bug is filed and get approval on the fact that the bug is critical
b) get the fix reviewed and landed in trunk first so that you only have to backport a single revision instead of working on two branches in parallel.

[Mike Pontillo (mpontillo)]

Investigation needed (copy/paste from other MP):

We need to tweak the preseed to load the bonding driver and make sure the deploy fails. If it fails (and this fixes the problem), we need to file a critical bug, link this branch, and add a mention to the 1.8.0 changelog.

[Ricardo Bánffy (rbanffy)]

Looks harmless

review: Approve

[Raphaël Badin (rvb)]

FWIW, this wasn't getting landed because the commit message was missing ;).

=== modified file 'etc/maas/templates/deployment-user-data/maas_configure_interfaces.py'
--- etc/maas/templates/deployment-user-data/maas_configure_interfaces.py	2015-05-07 18:14:38 +0000
+++ etc/maas/templates/deployment-user-data/maas_configure_interfaces.py	2015-06-16 23:34:21 +0000
@@ -26,7 +26,10 @@
 __metaclass__ = type
 
 from argparse import ArgumentParser
-from errno import ENOENT
+from errno import (
+    ENOENT,
+    ENOTDIR,
+)
 from logging import getLogger
 from os import (
     listdir,
@@ -120,9 +123,9 @@
             mac = read_file(
                 os.path.join('/sys/class/net', interface, 'address'))
         except IOError as e:
-            # Tolerate file-not-found errors, to absorb any variability in
-            # the /sys/class/net API that doesn't concern us.
-            if e.errno != ENOENT:
+            # Tolerate file or directory not found errors, to absorb any
+            # variability in the /sys/class/net API that doesn't concern us.
+            if e.errno != ENOENT and e.errno != ENOTDIR:
                 raise
         else:
             mac = normalise_mac(mac)