Merge pull request #2672 from odinuge/machine-info-backport-v0.35

Cherry-pick #2490  Make a copy of MachineInfo in GetMachineInfo() to v0.35

manager/manager.go

@@ -772,7 +772,8 @@ func (m *manager) GetMachineInfo() (*info.MachineInfo, error) {
 	m.machineMu.RLock()
 	defer m.machineMu.RUnlock()
 	// Copy and return the MachineInfo.
-	return &m.machineInfo, nil
+	machineInfoCopy := m.machineInfo
+	return &machineInfoCopy, nil
 }
 
 func (m *manager) GetVersionInfo() (*info.VersionInfo, error) {

manager/manager_test.go

@@ -177,6 +177,35 @@ func expectManagerWithContainersV2(containers []string, query *info.ContainerInf
 	return m, infosMap, handlerMap
 }
 
+func TestMachineInfoReturnValue(t *testing.T) {
+	containers := []string{
+		"/c1",
+		"/c2",
+	}
+
+	query := &info.ContainerInfoRequest{
+		NumStats: 256,
+	}
+
+	m, _, _ := expectManagerWithContainers(containers, query, t)
+
+	firstMachineInfo, err := m.GetMachineInfo()
+	if err != nil {
+		t.Fatalf("Unable to get machine info: %v", err)
+	}
+
+	secondMachineInfo, err := m.GetMachineInfo()
+	if err != nil {
+		t.Fatalf("Unable to get machine info: %v", err)
+	}
+
+	// Since the manager updates machine info in the background it should always return a copy
+	// to avoid race conditions at a later stage.
+	if firstMachineInfo == secondMachineInfo {
+		t.Fatalf("machineInfo should return a copy on each call")
+	}
+
+}
 func TestGetContainerInfo(t *testing.T) {
 	containers := []string{
 		"/c1",