[Bug 1069570] Re: 1 MAC Address, two IPs - DNS is "out of sync" with DHCP leases databases, I think...

[Dave Walker]

@stgraber, whilst I am not happy with the latest debdiff.. I do think
this issue requires closer consideration.  This is the only way that has
been determined to resolve multiple IP leases per boot (can consume up
to 3 different ones, with some configurations).  This means that pools
are quickly exhausted, which is a real issue in larger deployments.
Therefore, it would seem to be the best way to solve this bug.

Whilst this does introduce a new configuration option, it has a
seemingly low impact - as it doesn't change defaults, nor require
configuration changes to people upgrading - is a well documented change
in the manpage. And importantly, solves a larger bug that has been an
issue for some time.

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Title:
  1 MAC Address, two IPs - DNS is "out of sync" with DHCP leases
  databases, I think...

Status in juju-core:
  New
Status in MAAS:
  Triaged
Status in “isc-dhcp” package in Ubuntu:
  Fix Released
Status in “maas” package in Ubuntu:
  Invalid

Bug description:
  [Impact] 
   During my new tests, I tried to create two nodes simultaneously (both via DHCP + PXE, not by clicking "+Add node") and I hit this problem:

   Same MAC Address, two different IPs:

  # The format of this file is documented in the dhcpd.leases(5) manual page.
  # This lease file was written by isc-dhcp-4.2.4

  server-duid "\000\001\000\001\030\023\243\007RT\000\360\236\231";

  lease 192.168.50.1 {
    starts 5 2012/10/19 06:31:21;
    ends 5 2012/10/19 18:31:21;
    cltt 5 2012/10/19 06:31:21;
    binding state active;
    next binding state free;
    rewind binding state free;
    hardware ethernet 52:54:00:cd:6b:a2;
    uid "\001RT\000\315k\242";
  }
  lease 192.168.50.2 {
    starts 5 2012/10/19 06:31:43;
    ends 5 2012/10/19 18:31:43;
    cltt 5 2012/10/19 06:31:43;
    binding state active;
    next binding state free;
    rewind binding state free;
    hardware ethernet 52:54:00:cd:6b:a2;
    client-hostname "maas-enlist";
  }
  lease 192.168.50.2 {
    starts 5 2012/10/19 06:31:43;
    ends 5 2012/10/19 18:31:43;
    cltt 5 2012/10/19 06:31:43;
    binding state active;
    next binding state free;
    rewind binding state free;
    hardware ethernet 52:54:00:cd:6b:a2;
    client-hostname "maas-enlist";
  }
  host 192.168.50.1 {
    dynamic;
    hardware ethernet 52:54:00:cd:6b:a2;
    fixed-address 192.168.50.1;
  }
  lease 192.168.50.1 {
    starts 5 2012/10/19 06:31:21;
    ends 5 2012/10/19 06:34:48;
    tstp 5 2012/10/19 06:34:48;
    cltt 5 2012/10/19 06:31:21;
    binding state free;
    hardware ethernet 52:54:00:cd:6b:a2;
    uid "\001RT\000\315k\242";
  }

   1- DHCP gives address 192.168.50.1 to my machine on its first boot;

   2- After some time, I think that after some "reboots / elist /
  don'know for sure or even after commissioning" it; the IP have changed
  to 192.168.50.2 and got registered at DNS (192-168-50-2.test.com) that
  way;

   3- In the end of the day, after allocate it to root and start using
  it (the nodes), the DHCP gives again the IP 192.168.50.1 to my node,
  but DNS still remains with 192.158.50.2...

   ---

   My second node, first starts with 192.168.50.3, got registered with
  192.168.50.4 at DNS (and at MaaS Web GUI) but the DHCP finish with
  192.168.50.3...

  [Test Case]
  In a virtual environment: 
  - Add 2 nodes 
  - PXE boot the instances
  - verify dhcp leases have 1 mac address for 2 different IPs

  After applying latest debdiff alter the following:

     * modify /etc/maas/dhcpd.conf to include 'ignore-client-uids true'

  re-test by adding 2 additional nodes to verify the mac address is
  unique between both nodes.

  [Regression Potential]
  Low, as it adds another optional arguement to disable checking client-uids

  -- snip --

   I'll not try maas-dns again... Too many bugs...   =(

   I think that MaaS needs some kind of "glue" between DHCP and DNS to
  keep it in sync.

  Tks!
  Thiago

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