Comment 1 for bug 1694743

recent versions of the charms should support the proxy settings on the model if they are declared and pass them to the snapd systemd environment.

If you're using an earlier set of the charms, there is a snap_proxy configuration option that would need to be set in order to get snapd to respect the proxy. As snapd runs in a systemd service your environment profile does seem to do the trick, but was not the original solution to the issue.

This change landed in layer-snap about a month ago and is present in the latest two revisions of the kubernetes master and worker charms.