[Bug 231060] Re: packages dnsmasq and libvirt-bin conflict with each other

[Serge Hallyn]

Hi Brian,

until recently I wasn't quite sure if there might be a difference
between this bug and bug 928524.  There is not, so I will mark this bug
a duplicate of bug 928524, which has an SRU justification.

Thanks.

** Description changed:

+ ============ SRU justification ===========
+ Impact: libvirt fails to bring up virbr0 when dnsmasq is installed
+ Development fix: install a dnsmasq.d file to prevent the system-wide dnsmasq
+ from binding to virbr0.
+ Stable fix: same as Development fix
+ Test case:
+  virsh net-destroy virbr0 || true
+  sudo apt-get purge libvirt-bin
+  sudo apt-get -y install dnsmasq
+  sudo apt-get -y install libvirt-bin
+ Regression potential: There should be none, since we are simply telling the
+ system-wide dnsmasq (if any) not to bind to the virbr0 which our own dnsmasq
+ instance will bind to.
+ ===================================
+ 
  Binary package hint: libvirt-bin
  
  1. Release:
  
  Description:    Ubuntu 8.04
  Release:        8.04
  
  2. Policies:
  
  libvirt-bin:
-   Installed: 0.4.0-2ubuntu8
-   Candidate: 0.4.0-2ubuntu8
-   Version table:
-  *** 0.4.0-2ubuntu8 0
-         500 http://us.archive.ubuntu.com hardy/main Packages
-         100 /var/lib/dpkg/status
+   Installed: 0.4.0-2ubuntu8
+   Candidate: 0.4.0-2ubuntu8
+   Version table:
+  *** 0.4.0-2ubuntu8 0
+         500 http://us.archive.ubuntu.com hardy/main Packages
+         100 /var/lib/dpkg/status
  
  dnsmasq:
-   Installed: 2.41-2ubuntu1
-   Candidate: 2.41-2ubuntu1
-   Version table:
-  *** 2.41-2ubuntu1 0
-         500 http://us.archive.ubuntu.com hardy/universe Packages
-         100 /var/lib/dpkg/status
+   Installed: 2.41-2ubuntu1
+   Candidate: 2.41-2ubuntu1
+   Version table:
+  *** 2.41-2ubuntu1 0
+         500 http://us.archive.ubuntu.com hardy/universe Packages
+         100 /var/lib/dpkg/status
  
  3. Expected behavior: I expected the dnsmasq package not to interfere
  with the running of libvirt-bin.
  
  4. Actual behavior: What happened is that libvirt-bin became unable to
  provide DHCP services to guest OSes running in a kvm virtual machine.
  
  This is what I see in /var/log/syslog when libvirt-bin is able to start
  a virtual machine normally:
  
  May 16 08:25:57 bodhi avahi-daemon[5446]: Joining mDNS multicast group on interface vnet0.IPv4 with address 192.168.122.1.
  May 16 08:25:57 bodhi avahi-daemon[5446]: New relevant interface vnet0.IPv4 for mDNS.
  May 16 08:25:57 bodhi avahi-daemon[5446]: Registering new address record for 192.168.122.1 on vnet0.IPv4.
  May 16 08:25:57 bodhi dnsmasq[19217]: started, version 2.41 cachesize 150
  May 16 08:25:57 bodhi dnsmasq[19217]: compile time options: IPv6 GNU-getopt no-ISC-leasefile DBus I18N TFTP
  May 16 08:25:57 bodhi dnsmasq[19217]: DHCP, IP range 192.168.122.2 -- 192.168.122.254, lease time 1h
  May 16 08:25:57 bodhi dnsmasq[19217]: reading /etc/resolv.conf
  May 16 08:25:57 bodhi dnsmasq[19217]: using nameserver 192.168.2.1#53
  May 16 08:25:57 bodhi dnsmasq[19217]: read /etc/hosts - 9 addresses
  
  This is what I see when dnsmasq is installed:
  
  May 16 08:16:55 bodhi dnsmasq[18482]: failed to bind listening socket for 192.168.122.1: Address already in use
  May 16 08:16:55 bodhi dnsmasq[18482]: FAILED to start up
  
  Observations and workaround:
  
  1. It is possible to restore normal functioning while keeping both
  packages installed:
  
  $ sudo /etc/init.d/dnsmasq stop
  
  After this, libvirt-bin will work properly.  However this is obviously
  not a permanent solution.  If dnsmasq is not required to be present on
  the machine, then the package can be removed and libvirt-bin
  functionality will be restored (until something else breaks it).
  
  2. It seems the problem is that dnsmasq is started by the OS when
  booting and then libvirt-bin tries to start it again for its own
  purposes.
  
  3. I do not know what the proper fix is.  Is it stupid to want both
  dnsmasq and libvirt-bin installed at the same time on the same system?
  Must libvirt-bin be fixed to handle this situation?  I don't know.  I
  installed dnsmasq based on a suggestion that dnsmasq was required for
  libvirt to provide DHCP services to guest OSes but apparently only
  dnsmasq-base is required for that.  So the information I got was
  erroneous but it does not change the fact that the current packaging
  specs do not prevent users from shooting themselves in the foot.

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Title:
  packages dnsmasq and libvirt-bin conflict with each other

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