dns zoneconfig error with ranges of one IP length

[Paolo de Rosa]

Platform MAAS 2.0 Xenial

Our customer is using MAAS to provide dhcp service on /30 networks, IP range has only one address reserved ad dynamic range so MAAS generates DHCP configuration correctly but it has an issue generating bind zones.

For example when there is a network like 172.16.0.4/30 where 172.16.0.6 is the gateway and 172.16.0.5 is the only one IP in the dynamic range what happens is that in file /usr/lib/python3/dist-packages/provisioningserver/dns/zoneconfig.py function get_details_for_ip_range(ip_range)will be called with only one element.

The traceback below is reported by the region controller:

Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011Traceback (most recent call last):
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3.5/threading.py", line 862, in run
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 self._target(*self._args, **self._kwargs)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 904, in worker
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 return target()
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/twisted/_threads/_threadworker.py", line 46, in work
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 task()
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/twisted/_threads/_team.py", line 190, in doWork
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 task()
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011--- <exception caught here> ---
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 246, in inContext
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 result = inContext.theWork()
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 262, in <lambda>
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 inContext.theWork = lambda: context.call(ctx, func, *args, **kw)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 118, in callWithContext
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 return self.currentContext().callWithContext(ctx, func, *args, **kw)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 81, in callWithContext
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 return func(*args,**kw)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 937, in callInContext
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 return func(*args, **kwargs)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 602, in call_within_transaction
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 return func_outside_txn(*args, **kwargs)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 421, in retrier
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 return func(*args, **kwargs)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3.5/contextlib.py", line 30, in inner
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 return func(*args, **kwds)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/maasserver/dns/config.py", line 65, in dns_update_all_zones
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 bind_write_zones(zones)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/provisioningserver/dns/actions.py", line 143, in bind_write_zones
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 zone.write_config()
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/provisioningserver/dns/zoneconfig.py", line 303, in write_config
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 for dynamic_range in self._dynamic_ranges
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/provisioningserver/dns/zoneconfig.py", line 304, in <genexpr>
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 if dynamic_range.version == 4
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/provisioningserver/dns/zoneconfig.py", line 275, in get_GENERATE_directives
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 subnets, prefix, rdns_suffix = get_details_for_ip_range(dynamic_range)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/provisioningserver/dns/zoneconfig.py", line 78, in get_details_for_ip_range
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 cidr = spanning_cidr(ip_range)
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 File "/usr/lib/python3/dist-packages/netaddr/ip/__init__.py", line 1661, in spanning_cidr
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011 raise ValueError('IP sequence must contain at least 2 elements!')
Aug 22 13:35:31 maasregioncontroller1 sh[27208]: #011builtins.ValueError: IP sequence must contain at least 2 elements!