Ignore any .mount cgroup in docker

container/docker/factory.go

@@ -141,17 +141,21 @@ func ContainerNameToDockerId(name string) string {
 	return id
 }
 
+// isContainerName returns true if the cgroup with associated name
+// corresponds to a docker container.
 func isContainerName(name string) bool {
+	// always ignore .mount cgroup even if associated with docker and delegate to systemd
+	if strings.HasSuffix(name, ".mount") {
+		return false
+	}
 	return dockerCgroupRegexp.MatchString(path.Base(name))
 }
 
 // Docker handles all containers under /docker
 func (self *dockerFactory) CanHandleAndAccept(name string) (bool, bool, error) {
-	// docker factory accepts all containers it can handle.
-	canAccept := true
-
+	// if the container is not associated with docker, we can't handle it or accept it.
 	if !isContainerName(name) {
-		return false, canAccept, fmt.Errorf("invalid container name")
+		return false, false, nil
 	}
 
 	// Check if the container is known to docker and it is active.
@@ -160,10 +164,10 @@ func (self *dockerFactory) CanHandleAndAccept(name string) (bool, bool, error) {
 	// We assume that if Inspect fails then the container is not known to docker.
 	ctnr, err := self.client.ContainerInspect(context.Background(), id)
 	if err != nil || !ctnr.State.Running {
-		return false, canAccept, fmt.Errorf("error inspecting container: %v", err)
+		return false, true, fmt.Errorf("error inspecting container: %v", err)
 	}
 
-	return true, canAccept, nil
+	return true, true, nil
 }
 
 func (self *dockerFactory) DebugInfo() map[string][]string {

container/docker/factory_test.go

@@ -49,3 +49,24 @@ func TestEnsureThinLsKernelVersion(t *testing.T) {
 		}
 	}
 }
+
+func TestIsContainerName(t *testing.T) {
+	tests := []struct {
+		name     string
+		expected bool
+	}{
+		{
+			name:     "/system.slice/var-lib-docker-overlay-9f086b233ab7c786bf8b40b164680b658a8f00e94323868e288d6ce20bc92193-merged.mount",
+			expected: false,
+		},
+		{
+			name:     "/system.slice/docker-72e5a5ff5eef3c4222a6551b992b9360a99122f77d2229783f0ee0946dfd800e.scope",
+			expected: true,
+		},
+	}
+	for _, test := range tests {
+		if actual := isContainerName(test.name); actual != test.expected {
+			t.Errorf("%s: expected: %v, actual: %v", test.name, test.expected, actual)
+		}
+	}
+}