Use Network Manager to configure resolv.conf

IPA used to write a custom /etc/resolv.conf. On Fedora and RHEL,
NetworkManager is typically maintaining resolv.conf. On reboot or
restart of the service, NM overwrites the custom settings.

On systems with NM enabled, the DNS server installer now drops a config
file into NM's global config directory and delegates resolv.conf to NM.

On systems without NM, fall back to create /etc/resolv.conf directly.

Fixes: https://pagure.io/freeipa/issue/7900
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Thomas Woerner <twoerner@redhat.com>

ipaplatform/base/services.py

@@ -55,7 +55,7 @@ wellknownservices = ['certmonger', 'dirsrv', 'httpd', 'ipa', 'krb5kdc',
                      'rpcbind', 'kadmin', 'sshd', 'autofs', 'rpcgssd',
                      'rpcidmapd', 'pki_tomcatd', 'chronyd', 'domainname',
                      'named', 'ods_enforcerd', 'ods_signerd', 'gssproxy',
-                     'nfs-utils', 'sssd']
+                     'nfs-utils', 'sssd', 'NetworkManager']
 
 # The common ports for these services. This is used to wait for the
 # service to become available.