Check for non-active/supported cgroups

crosbymichael · crosbymichael · commit 4dacf2bc1300 · 2019-02-14T15:59:40.000-05:00
Signed-off-by: Michael Crosby &lt;crosbymichael@gmail.com&gt;
diff --git a/cgroup.go b/cgroup.go
@@ -35,14 +35,20 @@ func New(hierarchy Hierarchy, path Path, resources *specs.LinuxResources) (Cgrou
 	if err != nil {
 		return nil, err
 	}
+	var active []Subsystem
 	for _, s := range subsystems {
+		// check if subsystem exists
 		if err := initializeSubsystem(s, path, resources); err != nil {
+			if err == ErrControllerNotActive {
+				continue
+			}
 			return nil, err
 		}
+		active = append(active, s)
 	}
 	return &cgroup{
 		path:       path,
-		subsystems: subsystems,
+		subsystems: active,
 	}, nil
 }
 
@@ -60,6 +66,9 @@ func Load(hierarchy Hierarchy, path Path) (Cgroup, error) {
 			if os.IsNotExist(errors.Cause(err)) {
 				return nil, ErrCgroupDeleted
 			}
+			if err == ErrControllerNotActive {
+				continue
+			}
 			return nil, err
 		}
 		if _, err := os.Lstat(s.Path(p)); err != nil {
diff --git a/paths.go b/paths.go
@@ -57,6 +57,9 @@ func PidPath(pid int) Path {
 	return existingPath(paths, "")
 }
 
+// ErrControllerNotActive is returned when a controller is not supported or enalbed
+var ErrControllerNotActive = errors.New("controller is not supported")
+
 func existingPath(paths map[string]string, suffix string) Path {
 	// localize the paths based on the root mount dest for nested cgroups
 	for n, p := range paths {
@@ -77,7 +80,7 @@ func existingPath(paths map[string]string, suffix string) Path {
 		root, ok := paths[string(name)]
 		if !ok {
 			if root, ok = paths[fmt.Sprintf("name=%s", name)]; !ok {
-				return "", fmt.Errorf("unable to find %q in controller set", name)
+				return "", ErrControllerNotActive
 			}
 		}
 		if suffix != "" {
diff --git a/paths_test.go b/paths_test.go
@@ -112,3 +112,29 @@ func TestEmptySubsystem(t *testing.T) {
 		}
 	}
 }
+
+func TestSystemd240(t *testing.T) {
+	const data = `8:net_cls:/
+	7:memory:/system.slice/docker.service
+	6:freezer:/
+	5:blkio:/system.slice/docker.service
+	4:devices:/system.slice/docker.service
+	3:cpuset:/
+	2:cpu,cpuacct:/system.slice/docker.service
+	1:name=systemd:/system.slice/docker.service
+	0::/system.slice/docker.service`
+	r := strings.NewReader(data)
+	paths, err := parseCgroupFromReader(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	path := existingPath(paths, "")
+	_, err = path("net_prio")
+	if err == nil {
+		t.Fatal("error for net_prio shoulld not be nil")
+	}
+	if err != ErrControllerNotActive {
+		t.Fatalf("expected error %q but received %q", ErrControllerNotActive, err)
+	}
+}

Original file line number	Diff line number	Diff line change
`@@ -35,14 +35,20 @@ func New(hierarchy Hierarchy, path Path, resources *specs.LinuxResources) (Cgrou`
`35`	`35`	`if err != nil {`
`36`	`36`	`return nil, err`
`37`	`37`	`}`
	`38`	`+ var active []Subsystem`
`38`	`39`	`for _, s := range subsystems {`
	`40`	`+ // check if subsystem exists`
`39`	`41`	`if err := initializeSubsystem(s, path, resources); err != nil {`
	`42`	`+ if err == ErrControllerNotActive {`
	`43`	`+ continue`
	`44`	`+ }`
`40`	`45`	`return nil, err`
`41`	`46`	`}`
	`47`	`+ active = append(active, s)`
`42`	`48`	`}`
`43`	`49`	`return &cgroup{`
`44`	`50`	`path: path,`
`45`		`- subsystems: subsystems,`
	`51`	`+ subsystems: active,`
`46`	`52`	`}, nil`
`47`	`53`	`}`
`48`	`54`
`@@ -60,6 +66,9 @@ func Load(hierarchy Hierarchy, path Path) (Cgroup, error) {`
`60`	`66`	`if os.IsNotExist(errors.Cause(err)) {`
`61`	`67`	`return nil, ErrCgroupDeleted`
`62`	`68`	`}`
	`69`	`+ if err == ErrControllerNotActive {`
	`70`	`+ continue`
	`71`	`+ }`
`63`	`72`	`return nil, err`
`64`	`73`	`}`
`65`	`74`	`if _, err := os.Lstat(s.Path(p)); err != nil {`
Original file line number	Diff line number	Diff line change
`@@ -57,6 +57,9 @@ func PidPath(pid int) Path {`
`57`	`57`	`return existingPath(paths, "")`
`58`	`58`	`}`
`59`	`59`
	`60`	`+// ErrControllerNotActive is returned when a controller is not supported or enalbed`
	`61`	`+var ErrControllerNotActive = errors.New("controller is not supported")`
	`62`	`+`
`60`	`63`	`func existingPath(paths map[string]string, suffix string) Path {`
`61`	`64`	`// localize the paths based on the root mount dest for nested cgroups`
`62`	`65`	`for n, p := range paths {`
`@@ -77,7 +80,7 @@ func existingPath(paths map[string]string, suffix string) Path {`
`77`	`80`	`root, ok := paths[string(name)]`
`78`	`81`	`if !ok {`
`79`	`82`	`if root, ok = paths[fmt.Sprintf("name=%s", name)]; !ok {`
`80`		`- return "", fmt.Errorf("unable to find %q in controller set", name)`
	`83`	`+ return "", ErrControllerNotActive`
`81`	`84`	`}`
`82`	`85`	`}`
`83`	`86`	`if suffix != "" {`