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.
The *useproxy* role configures the `http_proxy` et al. environmet
variables for systemd services and interactive shells. Additionally, it
configures Yum repositories to use a single mirror via the `baseurl`
setting, rather than a list of mirrors via `metalink`, since the proxy
a) the proxy only allows access to _dl.fedoraproject.org_ and b) the
proxy caches RPM files, but this is only effective if all clients use
the same mirror all the time.
The `useproxy.yml` playbook applies this role to servers in the
*needproxy* group.
Dustin