Trap close error on shutdown

Fixes #1499

This traps any Accept() errors on server shutdown so that it exits
cleanly.

It also changes gracefulstop to stop on the grpc server as the daemon
will not shutdown if there are connected clients.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

server/server.go

@@ -8,6 +8,7 @@ import (
 	"net/http/pprof"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/boltdb/bolt"
 	containers "github.com/containerd/containerd/api/services/containers/v1"
@@ -129,14 +130,14 @@ func (s *Server) ServeGRPC(l net.Listener) error {
 	// handler.  This needs to be the last service registered so that it can collect
 	// metrics for every other service
 	grpc_prometheus.Register(s.rpc)
-	return s.rpc.Serve(l)
+	return trapClosedConnErr(s.rpc.Serve(l))
 }
 
 // ServeMetrics provides a prometheus endpoint for exposing metrics
 func (s *Server) ServeMetrics(l net.Listener) error {
 	m := http.NewServeMux()
 	m.Handle("/metrics", metrics.Handler())
-	return http.Serve(l, m)
+	return trapClosedConnErr(http.Serve(l, m))
 }
 
 // ServeDebug provides a debug endpoint
@@ -150,12 +151,12 @@ func (s *Server) ServeDebug(l net.Listener) error {
 	m.Handle("/debug/pprof/profile", http.HandlerFunc(pprof.Profile))
 	m.Handle("/debug/pprof/symbol", http.HandlerFunc(pprof.Symbol))
 	m.Handle("/debug/pprof/trace", http.HandlerFunc(pprof.Trace))
-	return http.Serve(l, m)
+	return trapClosedConnErr(http.Serve(l, m))
 }
 
-// Stop gracefully stops the containerd server
+// Stop the containerd server canceling any open connections
 func (s *Server) Stop() {
-	s.rpc.GracefulStop()
+	s.rpc.Stop()
 }
 
 func loadPlugins(config *Config) ([]*plugin.Registration, error) {
@@ -219,3 +220,13 @@ func interceptor(
 	}
 	return grpc_prometheus.UnaryServerInterceptor(ctx, req, info, handler)
 }
+
+func trapClosedConnErr(err error) error {
+	if err == nil {
+		return nil
+	}
+	if strings.Contains(err.Error(), "use of closed network connection") {
+		return nil
+	}
+	return err
+}