[Bug 1512749] Re: lxcbr0 dissappears on Ubuntu 15.10

[Stéphane Graber]

Confirmed that the new network-manager does fix the issue here. I've now
uploaded a reverted lxc.

** Changed in: lxc (Ubuntu Wily)
       Status: Triaged => Invalid

** Changed in: lxc (Ubuntu Xenial)
       Status: Triaged => Invalid

** Description changed:

- After initial upgrade from Ubuntu 15.04 to Ubuntu 15.10 LXC worked for a
- couple days then failed.   I found that the lxcbr0 interface no longer
- existed.
+ === SRU ===
+ Rationale:
+  Network Manager in wily triggers on newly created interfaces and resets their network configuration even though it's not supposed to manage them at all.
+  This breaks LXC and quite possibly libvirt as those provide bridges which are then completely unconfigured by Network Manager.
+ 
+ Test case:
+  1) Update (or not) network-manager
+  2) Restart it
+  3) Install lxc
+  4) Check that lxcbr0 exists and has an IP configured
+ 
+ Regression potential:
+  The change to Network Manager is related to udev handling of new devices, even though normal operation on a regular desktop machine was tested, it's not impossible that this may regress handling of some devices.
+  The fix was cherry-picked directly from upstream, so did go through code review and has been publicly available for a while.
+ 
+  This fixes a significant regression compared to Ubuntu 15.04 and looks
+ less risky than the alternative workaround which was uploaded earlier.
+ 
+ 
+ === Original report ===
+ After initial upgrade from Ubuntu 15.04 to Ubuntu 15.10 LXC worked for a couple days then failed.   I found that the lxcbr0 interface no longer existed.
  
  I reported this on the lxc-user alias and about the same time several
  others had this happen to them also.
  
  Serge Hallyn requested I open a launchpad bug and post some info but
  before I could gather that info the system returned to normal (re lxcbr0
  was back) the next day after the server was booted up again.
  
  note:   at least one other person had this happen to them also (lxcbr0
  came back by itself).
  
  Today, I booted this server again and ... again lxcbr0 was missing where
  it had been working last night.
  
  Below is all of the Info Serge Hallyn asked me to post.
  
  $ ifconfig lxcbr0
  lxcbr0: error fetching interface information: Device not found
- 
  
  $ journalctl -u lxc-net
  -- Logs begin at Tue 2015-11-03 07:25:22 EST, end at Tue 2015-11-03 10:02:08 EST
  Nov 03 07:25:48 server3 systemd[1]: Starting LXC network bridge setup...
  Nov 03 07:25:50 server3 lxc-net[913]: dnsmasq: failed to create listening socket
  Nov 03 07:25:50 server3 lxc-net[913]: Failed to setup lxc-net.
  Nov 03 07:25:50 server3 systemd[1]: Started LXC network bridge setup.
  
  root at server3:/home/bmullan# /usr/lib/x86_64-linux-gnu/lxc/lxc-net stop         # note - execution just returns to command line
  root at server3:/home/bmullan#
  
  >> and lxcbr0 is still missing
  
  # ifconfig lxcbr0
  lxcbr0: error fetching interface information: Device not found
  
  root at server3:/home/bmullan# /usr/lib/x86_64-linux-gnu/lxc/lxc-net start
  
  dnsmasq: failed to create listening socket for 10.0.3.1: Cannot assign requested address
  Failed to setup lxc-net.
  root at server3:/home/bmullan#
  
  $ uname -a
  Linux server3 4.2.0-16-generic #19-Ubuntu SMP Thu Oct 8 15:35:06 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
  
  $ lsb_release -a
  No LSB modules are available.
  Distributor ID:    Ubuntu
  Description:    Ubuntu 15.10
  Release:    15.10
  Codename:    wily

** Changed in: network-manager (Ubuntu Wily)
       Status: Triaged => Fix Committed

** Tags added: verification-needed

-- 
You received this bug notification because you are a member of Ubuntu
Server Team, which is subscribed to lxc in Ubuntu.
https://bugs.launchpad.net/bugs/1512749

Title:
  lxcbr0 dissappears on Ubuntu 15.10

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1512749/+subscriptions