instances cannot resolve their own hostname

This is still an issue with latest yakkety-proposed juju-2.0 2.0~beta17-0ubuntu1.16.10.1.

$ lxc exec juju-68160d-0 -- sh -c 'ping `hostname`'
ping: unknown host juju-68160d-0

This breaks e. g. the standard rabbitmq-server charm:

2016-09-07 20:08:24 INFO config-changed Traceback (most recent call last):
2016-09-07 20:08:24 INFO config-changed File "/var/lib/juju/agents/unit-rabbitmq-server-0/charm/hooks/config-changed", line 724, in <module>
2016-09-07 20:08:24 INFO config-changed hooks.execute(sys.argv)
2016-09-07 20:08:24 INFO config-changed File "/var/lib/juju/agents/unit-rabbitmq-server-0/charm/hooks/charmhelpers/core/hookenv.py", line 717, in execute
2016-09-07 20:08:24 INFO config-changed self._hooks[hook_name]()
2016-09-07 20:08:24 INFO config-changed File "/var/lib/juju/agents/unit-rabbitmq-server-0/charm/hooks/rabbit_utils.py", line 734, in wrapped_f
2016-09-07 20:08:24 INFO config-changed f(*args, **kwargs)
2016-09-07 20:08:24 INFO config-changed File "/var/lib/juju/agents/unit-rabbitmq-server-0/charm/hooks/config-changed", line 657, in config_changed
2016-09-07 20:08:24 INFO config-changed configure_nodename()
2016-09-07 20:08:24 INFO config-changed File "/var/lib/juju/agents/unit-rabbitmq-server-0/charm/hooks/config-changed", line 113, in configure_nodename
2016-09-07 20:08:24 INFO config-changed nodename = rabbit.get_local_nodename()
2016-09-07 20:08:24 INFO config-changed File "/var/lib/juju/agents/unit-rabbitmq-server-0/charm/hooks/rabbit_utils.py", line 672, in get_local_nodename
2016-09-07 20:08:24 INFO config-changed ip_addr = get_host_ip(unit_get('private-address'))
2016-09-07 20:08:24 INFO config-changed File "/var/lib/juju/agents/unit-rabbitmq-server-0/charm/hooks/charmhelpers/contrib/network/ip.py", line 417, in get_host_ip
2016-09-07 20:08:24 INFO config-changed ip_addr = ns_query(hostname)
2016-09-07 20:08:24 INFO config-changed File "/var/lib/juju/agents/unit-rabbitmq-server-0/charm/hooks/charmhelpers/contrib/network/ip.py", line 403, in ns_query
2016-09-07 20:08:24 INFO config-changed answers = dns.resolver.query(address, rtype)
2016-09-07 20:08:24 INFO config-changed File "/usr/lib/python2.7/dist-packages/dns/resolver.py", line 981, in query
2016-09-07 20:08:24 INFO config-changed raise_on_no_answer, source_port)
2016-09-07 20:08:24 INFO config-changed File "/usr/lib/python2.7/dist-packages/dns/resolver.py", line 910, in query
2016-09-07 20:08:24 INFO config-changed raise NXDOMAIN
2016-09-07 20:08:24 INFO config-changed dns.resolver.NXDOMAIN
2016-09-07 20:08:24 ERROR juju.worker.uniter.operation runhook.go:107 hook "config-changed" failed: exit status 1

Status changed to 'Confirmed' because the bug affects multiple users.

I'm unable to reproduce this in beta18, although I was definitely seeing it a couple of days ago.
Maybe it's been recently fixed?

beta18 is not in yakkety-proposed yet, so I cannot test this yet. Is it available from some PPA?

Hmm, I tried with some older builds and also don't see it on this machine, but I was seeing it on the other one I was using. So I'll need to chase it on that one (and hopefully work out why it's not happening on this one at the same time).

If we use manage_etc_hosts: "true" then we will get:

 127.0.1.1 vmhost.home vmhost

(for example).

I'm concerned about how well charms would hold out if they were always using localhost-esque addresses.

For the LXD container case also take a look at:

 https://bugs.launchpad.net/juju/+bug/1623480

Fixing that bug I believe would fix the container case.

@2-xtian - if you're testing on MAAS 2.0 then I suspect you're seeing perfectly working DNS for hosts and their containers. Bootstrap across AWS, GCE, and in particular Azure to see the issues on the public clouds.

Note: we are also proposing to land the following as an additional solution for the public clouds _and_ charms:

  https://github.com/frobware/nss-juju

It won't fix the general case of:

  $ lxc exec juju-68160d-0 -- sh -c 'ping `hostname`'

though see my comment about container hostname resolution in comment #6.

And for completness:

 https://github.com/dimitern/juju/commit/60e89f1d6cb02f3f0f9f36dbf8e3156ad4e9f7e8

that tree has, as a PoC, support for returning hostname that will work with nss-juju.

Is at least fixed on 2.1.3