Use containerd client `Reconnect()` API.

This fixes an issue where the containerd client is cached in a container
object in libcontainerd and becomes stale after containerd is restarted.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

libcontainerd/client_daemon.go

@@ -114,6 +114,13 @@ type client struct {
 	containers map[string]*container
 }
 
+func (c *client) reconnect() error {
+	c.Lock()
+	err := c.remote.Reconnect()
+	c.Unlock()
+	return err
+}
+
 func (c *client) setRemote(remote *containerd.Client) {
 	c.Lock()
 	c.remote = remote

libcontainerd/remote_daemon.go

@@ -309,20 +309,17 @@ func (r *remote) monitorConnection(monitor *containerd.Client) {
 		}
 		<-r.daemonWaitCh
 
-		monitor.Close()
 		os.Remove(r.GRPC.Address)
 		if err := r.startContainerd(); err != nil {
 			r.logger.WithError(err).Error("failed restarting containerd")
 			continue
 		}
 
-		newMonitor, err := containerd.New(r.GRPC.Address)
-		if err != nil {
+		if err := monitor.Reconnect(); err != nil {
 			r.logger.WithError(err).Error("failed connect to containerd")
 			continue
 		}
 
-		monitor = newMonitor
 		var wg sync.WaitGroup
 
 		for _, c := range r.clients {
@@ -331,18 +328,12 @@ func (r *remote) monitorConnection(monitor *containerd.Client) {
 			go func(c *client) {
 				defer wg.Done()
 				c.logger.WithField("namespace", c.namespace).Debug("creating new containerd remote client")
-				c.remote.Close()
-
-				remote, err := containerd.New(r.GRPC.Address, containerd.WithDefaultNamespace(c.namespace))
-				if err != nil {
+				if err := c.reconnect(); err != nil {
 					r.logger.WithError(err).Error("failed to connect to containerd")
 					// TODO: Better way to handle this?
 					// This *shouldn't* happen, but this could wind up where the daemon
 					// is not able to communicate with an eventually up containerd
-					return
 				}
-
-				c.setRemote(remote)
 			}(c)
 
 			wg.Wait()

libcontainerd/remote_daemon_options_linux.go

@@ -16,19 +16,3 @@ func (o oomScore) Apply(r Remote) error {
 	}
 	return fmt.Errorf("WithOOMScore option not supported for this remote")
 }
-
-// WithSubreaper sets whether containerd should register itself as a
-// subreaper
-func WithSubreaper(reap bool) RemoteOption {
-	return subreaper(reap)
-}
-
-type subreaper bool
-
-func (s subreaper) Apply(r Remote) error {
-	if remote, ok := r.(*remote); ok {
-		remote.NoSubreaper = !bool(s)
-		return nil
-	}
-	return fmt.Errorf("WithSubreaper option not supported for this remote")
-}