Although running `dnf` from the command line works without explicitly
configuring the proxy, because it inherits the environment variables set
by PAM on login from the user's shell, the `dnf` Ansible module does
not, as it does not inherit those variables. Thus, we need to
explicitly configure the `proxy` setting in `dnf.conf` in order to be
able to install packages via Ansible.
Since `dnf` does not have separate settings for different protocols
(e.g. HTTP, HTTPS, FTP), we need a way to specify which of the
configured proxies to use if there are multiple. As such, the
*useproxy* role will attempt to use the value of the `dnf_proxy`
variable, if it is set, falling back to `yum_proxy` and finally
`http_proxy`. This should cover most situations without any explicit
configuration, but allows flexibility for other cases.
Dustin
daa59bdba5