Add a warning when using system-upgrade on RHEL

dnf-plugins-core.spec

@@ -148,14 +148,13 @@ Summary:    Core Plugins for DNF
 %{?python_provide:%python_provide python3-%{name}}
 BuildRequires:  python3-dbus
 BuildRequires:  python3-devel
+BuildRequires:  python3-distro
 BuildRequires:  python3-dnf >= %{dnf_lowest_compatible}
 BuildRequires:  python3-systemd
 BuildRequires:  pkgconfig(systemd)
 BuildRequires:  systemd
 %{?systemd_ordering}
-%if 0%{?fedora}
 Requires:       python3-distro
-%endif
 Requires:       python3-dbus
 Requires:       python3-dnf >= %{dnf_lowest_compatible}
 Requires:       python3-hawkey >= %{hawkey_version}

doc/system-upgrade.rst

@@ -27,13 +27,15 @@ DNF system-upgrades plugin provides three commands: ``system-upgrade``, ``offlin
 ``offline-distrosync``. Only ``system-upgrade`` command requires increase of distribution major
 version (``--releasever``) compared to installed version.
 
-``dnf system-upgrade`` can be used to upgrade a Fedora system to a new major
-release. It replaces fedup (the old Fedora Upgrade tool). Before you proceed ensure that your system
+``dnf system-upgrade`` is a recommended way to upgrade a system to a new major release.
+It replaces fedup (the old Fedora Upgrade tool). Before you proceed ensure that your system
 is fully upgraded (``dnf --refresh upgrade``).
 
 The ``system-upgrade`` command also performes additional actions necessary for the upgrade of the
 system, for example an upgrade of groups and environments.
 
+.. WARNING:: The ``system-upgrade`` command is not supported on the RHEL distribution.
+
 --------
 Synopsis
 --------

plugins/system_upgrade.py

@@ -20,6 +20,7 @@
 """system_upgrade.py - DNF plugin to handle major-version system upgrades."""
 
 from subprocess import call, Popen, check_output, CalledProcessError
+import distro
 import json
 import os
 import os.path
@@ -451,6 +452,9 @@ def pre_configure_clean(self):
 
     def configure_download(self):
         if 'system-upgrade' == self.opts.command or 'fedup' == self.opts.command:
+            if distro.id() == 'rhel':
+                logger.warning(_('WARNING: this operation is not supported on the RHEL distribution. '
+                                 'Proceed at your own risk.'))
             help_url = get_url_from_os_release()
             if help_url:
                 msg = _('Additional information for System Upgrade: {}')