Comment 3 for bug 1883656

If I recall correctly, the juju proxy settings were specifically designed not to be used to interfere with the system wide proxy settings. This was because issues arose when juju needed specific values set that then messed up the non-juju networking requirements of the host.

The idea is that charm and other juju artefacts explicitly can query the various juju proxy values and do the right thing. If a specific charm needs to set system proxy values from the juju ones, it can do so. But, by design, this is not the default behaviour. I haven't got specific examples I can relate as the the issues that were encountered, but it was a mess.