Fabric config change only applies restart to the node that has a change

hooks/pg_dir_hooks.py

@@ -30,6 +30,7 @@ from pg_dir_utils import (
     ensure_mtu,
     add_lcm_key,
     post_pg_license,
+    fabric_interface_changed
 )
 
 hooks = Hooks()
@@ -71,6 +72,15 @@ def config_changed():
     if add_lcm_key():
         log("PLUMgrid LCM Key added")
         return 1
+    charm_config = config()
+    if charm_config.changed('fabric-interfaces'):
+        if not fabric_interface_changed():
+            log("Fabric interface already set")
+            return 1
+    if charm_config.changed('os-data-network'):
+        if charm_config['fabric-interfaces'] == 'MANAGEMENT':
+            log('Fabric running on managment network')
+            return 1
     stop_pg()
     configure_sources(update=True)
     pkgs = determine_packages()

hooks/pg_dir_utils.py

@@ -198,6 +198,22 @@ def get_mgmt_interface():
         return get_iface_from_addr(unit_get('private-address'))
 
 
+def fabric_interface_changed():
+    '''
+    Returns true if interface for node changed.
+    '''
+    fabric_interface = get_fabric_interface()
+    try:
+        with open(PG_IFCS_CONF, 'r') as ifcs:
+            for line in ifcs:
+                if 'fabric_core' in line:
+                    if line.split()[0] == fabric_interface:
+                        return False
+    except IOError:
+        return True
+    return True
+
+
 def get_fabric_interface():
     '''
     Returns the fabric interface.