Bug 674358

Summary: failure to start dnsmasq not reported to libvirt-manager
Product: [Community] Virtualization Tools Reporter: Brian J. Murrell <brian>
Component: libvirtAssignee: Libvirt Maintainers <libvirt-maint>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: unspecified    
Version: unspecifiedCC: berrange, crobinso, laine, xen-maint
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Last Closed: 2014-02-14 10:50:41 UTC Type: ---
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Description Brian J. Murrell 2011-02-01 15:51:54 UTC 
Description of problem:
Discovered when testing/debugging the issue reported in bug 674356, if the dnsmasq server fails to start it happens with an incorrect failure message.

Version-Release number of selected component (if applicable):
0.8.4

How reproducible:
100%

Steps to Reproduce:
See steps in bug 674356
  
Actual results:
In virt-manager one gets the following error:

Error creating virtual network: internal error '/sbin/iptables --table mangle --delete POSTROUTING --out-interface virbr2 --protocol udp --destination-port 68 --jump CHECKSUM --checksum-fill' exited with non-zero status 2 and signal 0: iptables v1.4.4: unknown option `--checksum-fill'
Try `iptables -h' or 'iptables --help' for more information.

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/createnet.py", line 349, in finish
    self.conn.create_network(xml)
  File "/usr/share/virt-manager/virtManager/connection.py", line 755, in create_network
    net.create()
  File "/usr/lib/python2.6/dist-packages/libvirt.py", line 866, in create
    if ret == -1: raise libvirtError ('virNetworkCreate() failed', net=self)
libvirtError: internal error '/sbin/iptables --table mangle --delete POSTROUTING --out-interface virbr2 --protocol udp --destination-port 68 --jump CHECKSUM --checksum-fill' exited with non-zero status 2 and signal 0: iptables v1.4.4: unknown option `--checksum-fill'
Try `iptables -h' or 'iptables --help' for more information.

Expected results:
Should see a failure message logged by libvirtd reflecting the failure to start dnsmasq.

The reported error is of course a red herring in that it's a non-fatal error.  What is fatal though is the failure to start dnsmasq and that goes completely unreported.
Comment 1 Laine Stump 2014-02-14 10:50:41 UTC 
Not sure how I previously hadn't seen this old bug, but it's really a non-bug now, since any modern Linux system will have an iptables new enough to support the --checksum-fill option, and even if not a WARN level message in the log will urge upgrading to a newer iptables that does support --checksum-fill. As for this error obscuring a different error relating to failure to start dnsmasq, I can't see how that would have happened, even back at 0.8.4, since a failure of this iptables command does not prevent an attempt to start dnsmasq, and an earlier error can never overwrite a later error (only vice-versa); apparently that was handled in a separate BZ that is long since closed.