From 1ffe6fef0297e5ef82bdc91774917a52e47531d9 Mon Sep 17 00:00:00 2001
From: Jana Radhakrishnan <mrjana@docker.com>
Date: Fri, 9 Oct 2015 13:43:25 -0700
Subject: [PATCH] Move sandbox resources when container restarts

Currently when container has a restart policy and gets
restarted, docker does not release networking and allocate
it back. But it presents libnetwork with a new sandbox while
all the network resources are locked in the old sandbox. This
commit attempts to move all the network resources from the old
sandbox to the new sandbox when libnetwork is presented with the
new sandbox.

Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>
---
 libnetwork/sandbox.go | 75 +++++++++++++++++++++++++++++--------------
 1 file changed, 51 insertions(+), 24 deletions(-)

diff --git a/libnetwork/sandbox.go b/libnetwork/sandbox.go
index b56431112c..454ed57715 100644
--- a/libnetwork/sandbox.go
+++ b/libnetwork/sandbox.go
@@ -307,15 +307,21 @@ func (sb *sandbox) SetKey(basePath string) error {
 	}
 
 	sb.Lock()
-	if sb.osSbox != nil {
-		sb.Unlock()
-		return types.ForbiddenErrorf("failed to set sandbox key : already assigned")
-	}
+	osSbox := sb.osSbox
 	sb.Unlock()
-	osSbox, err := osl.GetSandboxForExternalKey(basePath, sb.Key())
+
+	if osSbox != nil {
+		// If we already have an OS sandbox, release the network resources from that
+		// and destroy the OS snab. We are moving into a new home further down. Note that none
+		// of the network resources gets destroyed during the move.
+		sb.releaseOSSbox()
+	}
+
+	osSbox, err = osl.GetSandboxForExternalKey(basePath, sb.Key())
 	if err != nil {
 		return err
 	}
+
 	sb.Lock()
 	sb.osSbox = osSbox
 	sb.Unlock()
@@ -335,6 +341,45 @@ func (sb *sandbox) SetKey(basePath string) error {
 	return nil
 }
 
+func releaseOSSboxResources(osSbox osl.Sandbox, ep *endpoint) {
+	for _, i := range osSbox.Info().Interfaces() {
+		// Only remove the interfaces owned by this endpoint from the sandbox.
+		if ep.hasInterface(i.SrcName()) {
+			if err := i.Remove(); err != nil {
+				log.Debugf("Remove interface failed: %v", err)
+			}
+		}
+	}
+
+	ep.Lock()
+	joinInfo := ep.joinInfo
+	ep.Unlock()
+
+	// Remove non-interface routes.
+	for _, r := range joinInfo.StaticRoutes {
+		if err := osSbox.RemoveStaticRoute(r); err != nil {
+			log.Debugf("Remove route failed: %v", err)
+		}
+	}
+}
+
+func (sb *sandbox) releaseOSSbox() {
+	sb.Lock()
+	osSbox := sb.osSbox
+	sb.osSbox = nil
+	sb.Unlock()
+
+	if osSbox == nil {
+		return
+	}
+
+	for _, ep := range sb.getConnectedEndpoints() {
+		releaseOSSboxResources(osSbox, ep)
+	}
+
+	osSbox.Destroy()
+}
+
 func (sb *sandbox) populateNetworkResources(ep *endpoint) error {
 	sb.Lock()
 	if sb.osSbox == nil {
@@ -394,25 +439,7 @@ func (sb *sandbox) clearNetworkResources(origEp *endpoint) error {
 	osSbox := sb.osSbox
 	sb.Unlock()
 	if osSbox != nil {
-		for _, i := range osSbox.Info().Interfaces() {
-			// Only remove the interfaces owned by this endpoint from the sandbox.
-			if ep.hasInterface(i.SrcName()) {
-				if err := i.Remove(); err != nil {
-					log.Debugf("Remove interface failed: %v", err)
-				}
-			}
-		}
-
-		ep.Lock()
-		joinInfo := ep.joinInfo
-		ep.Unlock()
-
-		// Remove non-interface routes.
-		for _, r := range joinInfo.StaticRoutes {
-			if err := osSbox.RemoveStaticRoute(r); err != nil {
-				log.Debugf("Remove route failed: %v", err)
-			}
-		}
+		releaseOSSboxResources(osSbox, ep)
 	}
 
 	sb.Lock()