Handling container rename in libnetwork

Signed-off-by: Santhosh Manohar <santhosh@docker.com>

libnetwork/controller.go

@@ -143,6 +143,7 @@ type controller struct {
 	watchCh        chan *endpoint
 	unWatchCh      chan *endpoint
 	svcDb          map[string]svcMap
+	nmap           map[string]*netWatch
 	sync.Mutex
 }
 

libnetwork/endpoint.go

@@ -431,6 +431,51 @@ func (ep *endpoint) sbJoin(sbox Sandbox, options ...EndpointOption) error {
 	return sb.clearDefaultGW()
 }
 
+func (ep *endpoint) rename(name string) error {
+	var err error
+	n := ep.getNetwork()
+	if n == nil {
+		return fmt.Errorf("network not connected for ep %q", ep.name)
+	}
+
+	n.getController().Lock()
+	netWatch, ok := n.getController().nmap[n.ID()]
+	n.getController().Unlock()
+
+	if !ok {
+		return fmt.Errorf("watch null for network %q", n.Name())
+	}
+
+	n.updateSvcRecord(ep, n.getController().getLocalEps(netWatch), false)
+
+	oldName := ep.name
+	ep.name = name
+
+	n.updateSvcRecord(ep, n.getController().getLocalEps(netWatch), true)
+	defer func() {
+		if err != nil {
+			n.updateSvcRecord(ep, n.getController().getLocalEps(netWatch), false)
+			ep.name = oldName
+			n.updateSvcRecord(ep, n.getController().getLocalEps(netWatch), true)
+		}
+	}()
+
+	// Update the store with the updated name
+	if err = n.getController().updateToStore(ep); err != nil {
+		return err
+	}
+	// After the name change do a dummy endpoint count update to
+	// trigger the service record update in the peer nodes
+
+	// Ignore the error because updateStore fail for EpCnt is a
+	// benign error. Besides there is no meaningful recovery that
+	// we can do. When the cluster recovers subsequent EpCnt update
+	// will force the peers to get the correct EP name.
+	_ = n.getEpCnt().updateStore()
+
+	return err
+}
+
 func (ep *endpoint) hasInterface(iName string) bool {
 	ep.Lock()
 	defer ep.Unlock()

libnetwork/endpoint_cnt.go

@@ -108,6 +108,25 @@ func (ec *endpointCnt) EndpointCnt() uint64 {
 	return ec.Count
 }
 
+func (ec *endpointCnt) updateStore() error {
+retry:
+	store := ec.n.getController().getStore(ec.DataScope())
+	if store == nil {
+		return fmt.Errorf("store not found for scope %s", ec.DataScope())
+	}
+
+	if err := ec.n.getController().updateToStore(ec); err != nil {
+		if err == datastore.ErrKeyModified {
+			if err := store.GetObject(datastore.Key(ec.Key()...), ec); err != nil {
+				return fmt.Errorf("could not update the kvobject to latest on rename: %v", err)
+			}
+			goto retry
+		}
+		return err
+	}
+	return nil
+}
+
 func (ec *endpointCnt) atomicIncDecEpCnt(inc bool) error {
 retry:
 	ec.Lock()

libnetwork/libnetwork_test.go

@@ -1134,6 +1134,10 @@ func (f *fakeSandbox) Delete() error {
 	return nil
 }
 
+func (f *fakeSandbox) Rename(name string) error {
+	return nil
+}
+
 func (f *fakeSandbox) SetKey(key string) error {
 	return nil
 }

libnetwork/sandbox.go

@@ -34,6 +34,8 @@ type Sandbox interface {
 	Refresh(options ...SandboxOption) error
 	// SetKey updates the Sandbox Key
 	SetKey(key string) error
+	// Rename changes the name of all attached Endpoints
+	Rename(name string) error
 	// Delete destroys this container after detaching it from all connected endpoints.
 	Delete() error
 }
@@ -201,6 +203,35 @@ func (sb *sandbox) Delete() error {
 	return nil
 }
 
+func (sb *sandbox) Rename(name string) error {
+	var err error
+	undo := []func(){}
+
+	for _, ep := range sb.getConnectedEndpoints() {
+		if ep.endpointInGWNetwork() {
+			continue
+		}
+
+		oldName := ep.Name()
+		lEp := ep
+		if err = ep.rename(name); err != nil {
+			break
+		}
+		undo = append(undo,
+			func() {
+				// Ignore the error while undoing
+				_ = lEp.rename(oldName)
+			})
+	}
+
+	if err != nil {
+		for _, f := range undo {
+			f()
+		}
+	}
+	return err
+}
+
 func (sb *sandbox) Refresh(options ...SandboxOption) error {
 	// Store connected endpoints
 	epList := sb.getConnectedEndpoints()

libnetwork/store.go

@@ -274,25 +274,30 @@ func (c *controller) networkWatchLoop(nw *netWatch, ep *endpoint, ecCh <-chan da
 					continue
 				}
 
-				if _, ok := nw.remoteEps[lEp.ID()]; ok {
-					delete(delEpMap, lEp.ID())
-					continue
+				if ep, ok := nw.remoteEps[lEp.ID()]; ok {
+					// On a container rename EP ID will remain
+					// the same but the name will change. service
+					// records should reflect the change.
+					// Keep old EP entry in the delEpMap and add
+					// EP from the store (which has the new name)
+					// into the new list
+					if lEp.name == ep.name {
+						delete(delEpMap, lEp.ID())
+						continue
+					}
 				}
-
 				nw.remoteEps[lEp.ID()] = lEp
 				addEp = append(addEp, lEp)
-
 			}
 			c.Unlock()
 
-			for _, lEp := range addEp {
-				ep.getNetwork().updateSvcRecord(lEp, c.getLocalEps(nw), true)
-			}
-
 			for _, lEp := range delEpMap {
 				ep.getNetwork().updateSvcRecord(lEp, c.getLocalEps(nw), false)
 
 			}
+			for _, lEp := range addEp {
+				ep.getNetwork().updateSvcRecord(lEp, c.getLocalEps(nw), true)
+			}
 		}
 	}
 }
@@ -378,13 +383,13 @@ func (c *controller) processEndpointDelete(nmap map[string]*netWatch, ep *endpoi
 	c.Unlock()
 }
 
-func (c *controller) watchLoop(nmap map[string]*netWatch) {
+func (c *controller) watchLoop() {
 	for {
 		select {
 		case ep := <-c.watchCh:
-			c.processEndpointCreate(nmap, ep)
+			c.processEndpointCreate(c.nmap, ep)
 		case ep := <-c.unWatchCh:
-			c.processEndpointDelete(nmap, ep)
+			c.processEndpointDelete(c.nmap, ep)
 		}
 	}
 }
@@ -392,7 +397,7 @@ func (c *controller) watchLoop(nmap map[string]*netWatch) {
 func (c *controller) startWatch() {
 	c.watchCh = make(chan *endpoint)
 	c.unWatchCh = make(chan *endpoint)
-	nmap := make(map[string]*netWatch)
+	c.nmap = make(map[string]*netWatch)
 
-	go c.watchLoop(nmap)
+	go c.watchLoop()
 }