Comment 5 for bug 1694743

Try setting the snap_proxy configuration value on both the worker and the masters and this should unblock you.

As indicated previously the fix to read the proxy configuration from model config went out with the bundles as of revision 31 forward (for kubernetes core) and revision 36 forward (canonical kubernetes) bundles.

you can set these config options like so:

juju config kubernetes-master snap_proxy=http://my.proxy.ip:3600
juju config kubernetes-worker snap_proxy=http://my.proxy.ip:3600

regardless of model config, these values will populate in the snapd proxy configuration and should get you moving.