lxd: BGP fixes (from Incus) (#15205)

Includes cherry-picks from lxc/incus#1805.

Author: tomponline

lxd/bgp/server.go

@@ -158,7 +158,7 @@ func (s *Server) stop() error {
 		oldPeers[peerUUID] = peer
 	}
 
-	// Remove all the peers (ignore failures).
+	// Remove all the peers.
 	for _, peer := range s.peers {
 		err := s.removePeer(peer.address)
 		if err != nil {

lxd/network/driver_ovn.go

@@ -3503,12 +3503,12 @@ func (n *ovn) Update(newNetwork api.NetworkPut, targetNode string, clientType re
 		if err != nil {
 			return err
 		}
-	}
-
-	// Setup BGP.
-	err = n.bgpSetup(oldNetwork.Config)
-	if err != nil {
-		return err
+	} else {
+		// Setup BGP.
+		err = n.bgpSetup(oldNetwork.Config)
+		if err != nil {
+			return err
+		}
 	}
 
 	revert.Success()

lxd/network/driver_physical.go

@@ -491,9 +491,16 @@ func (n *physical) Update(newNetwork api.NetworkPut, targetNode string, clientTy
 		return err
 	}
 
-	err = n.setup(oldNetwork.Config)
-	if err != nil {
-		return err
+	if !hostNameChanged {
+		err = n.setup(oldNetwork.Config)
+		if err != nil {
+			return err
+		}
+	} else {
+		err = n.setup(nil)
+		if err != nil {
+			return err
+		}
 	}
 
 	revert.Success()