dns-backend wget should ignore proxy

[Drew Freiberger]

When working on a cloud that must use proxy settings to connect to the internet, the charm's internal communication with peers is trying to use the proxy. While in some circumstatnces, we can include all of the no-proxy ips for the cloud, but for clouds with more than a /23 for internal/admin networks, the no_proxy variable overruns with IPs.

It would be helpful for the internal charm to charm communications for passing data either use the relation or use no-proxy on the wget to pull zone-sync files.

Error is:
subprocess.CalledProcessError: Command '['wget', 'http://10.55.12.135:80/zone-syncs/1539981718.2229562.tar.gz', '--retry-connrefused', '-t', '10']' returned non-zero exit status 8

Fails when hitting proxy that doesn't have access to the dns-backend space:
root@juju-a3b7c7-16-lxd-4:/tmp# wget http://10.55.12.135:80/zone-syncs/1539981718.2229562.tar.gz
--2018-10-23 15:13:17-- http://10.55.12.135/zone-syncs/1539981718.2229562.tar.gz
Connecting to 10.55.0.15:8000... connected.
Proxy request sent, awaiting response... 500 Internal Server Error
2018-10-23 15:13:17 ERROR 500: Internal Server Error.

Works when ip of peer is in no_proxy variable.
root@juju-a3b7c7-16-lxd-4:/tmp# no_proxy=10.55.12.135 wget http://10.55.12.135:80/zone-syncs/1539981718.2229562.tar.gz
--2018-10-23 15:14:01-- http://10.55.12.135/zone-syncs/1539981718.2229562.tar.gz
Connecting to 10.55.12.135:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 133 [application/x-gzip]
Saving to: ‘1539981718.2229562.tar.gz’

1539981718.2229562.tar.gz 100%[=====================================================================================================>] 133 --.-KB/s in 0s

[Drew Freiberger (afreiberger)]

workaround:

lib/charm/openstack/designate_bind.py line 421, add '--no-proxy' to cmd list.