[Bug 559605] [NEW] ADDRSPERNET > 256 causes null host entry in euca-dhcp.conf and dhcpd crashes

Piotr T Zbiegiel pzbiegiel at anl.gov
Fri Apr 9 22:37:22 BST 2010


Public bug reported:

I am running 1.6.2-0ubuntu27 of the eucalyptus packages on lucid-beta1.

Setting ADDRSPERNET to a value greater than 256 appears to cause
Eucalyptus to add a null host entry such as to euca-dhcp.conf:

host node-0.0.0.0 {
  hardware ethernet ;
  fixed-address 0.0.0.0;
}

dhcpd continues to run after the first instance but fails once a second
security group is added and VMs are allocated in that second security
group.  At that point dhcpd fails to restart because of the duplicate
host entries and will not restart.  This does not appear to occur with
ADDRSPERNET set to 256 but happens reliably when it is set to 512 or
1024.  On a separate note, no matter what ADDRSPERNET is set to, it does
not appear you can request more than ~253 VMs per security group even
though the iptables rules say you have a /23 or /22.

You should be able to reproduce this bug with the following:

1) Set ADDRSPERNET to 512 and restart eucalyptus with a CLEAN=1
2) Add a security group with the euca-add-groups command.
3) Allocate some VMs in that security group.  I had this happen with 1, 2, 100, 200, and 253.  My guess is that it happens no matter what you ask for.
4) Check the dhcp config file in /var/run/eucalyptus/net/euca-dhcp.conf.  The last host entry should look like the above.
5) DHCPD is most likely still running.  The VMs should allocate as normal and get IPs from DHCP as expected.
6) Allocate a second security group.
7) Request VMs in the second security group.  
8) Check status of dhcpd soon after this and it will most likely not be running.  cc.log will complain that it could not restart DHCP.

According to euca-describe instances the second set of VMs may get
assigned IPs and even start running but they will not be reachable and
euca-get-console output implies that they do not have working network
connections (failed access to metadata service, etc.).

Again, this problem does not appear to happen when ADDRSPERNET is set to
256.

** Affects: eucalyptus (Ubuntu)
     Importance: Undecided
         Status: New

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ADDRSPERNET > 256 causes null host entry in euca-dhcp.conf and dhcpd crashes
https://bugs.launchpad.net/bugs/559605
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