A simple forward proxy use for testing closed or restricted network
conditions.

Squid 3 is set up as forward proxy for client hosts on a closed or
restricted networks to access the outside network. Squid 3 can proxy
FTP, HTTP, and HTTPS.

This forward proxy works in tandem with the client-forwardproxy
subordinate charm. Any Juju application or provisioned machine
can be set up to use the forward proxy like so

    juju deploy squid-forwardproxy
    juju deploy xenial/ubuntu x1
    juju deploy client-forwardproxy --to 1
    juju add-relation client-forwardproxy:forwardproxy squid-forwardproxy:forwardproxy

Squid listens on port 3128 and will proxy all requested sites by
default. You can change the port. like so:

    juju config squid-forwardproxy port=4321

You can restrict the sites that will proxied:

    juju config squid-forwardproxy sitenames="ubuntu.com canonical.com"
