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Merge pull request #712 from iverberk/f-cgroup-finterprinter
Add periodic cgroup fingerprinter
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,88 @@ | ||
package fingerprint | ||
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import ( | ||
"fmt" | ||
"log" | ||
"time" | ||
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client "github.com/hashicorp/nomad/client/config" | ||
"github.com/hashicorp/nomad/nomad/structs" | ||
) | ||
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const ( | ||
cgroupAvailable = "available" | ||
cgroupUnavailable = "unavailable" | ||
interval = 15 | ||
) | ||
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type CGroupFingerprint struct { | ||
logger *log.Logger | ||
lastState string | ||
mountPointDetector MountPointDetector | ||
} | ||
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// An interface to isolate calls to the cgroup library | ||
// This facilitates testing where we can implement | ||
// fake mount points to test various code paths | ||
type MountPointDetector interface { | ||
MountPoint() (string, error) | ||
} | ||
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// Implements the interface detector which calls the cgroups library directly | ||
type DefaultMountPointDetector struct { | ||
} | ||
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// Call out to the default cgroup library | ||
func (b *DefaultMountPointDetector) MountPoint() (string, error) { | ||
return FindCgroupMountpointDir() | ||
} | ||
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// NewCGroupFingerprint returns a new cgroup fingerprinter | ||
func NewCGroupFingerprint(logger *log.Logger) Fingerprint { | ||
f := &CGroupFingerprint{ | ||
logger: logger, | ||
lastState: cgroupUnavailable, | ||
mountPointDetector: &DefaultMountPointDetector{}, | ||
} | ||
return f | ||
} | ||
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// Fingerprint tries to find a valid cgroup moint point | ||
func (f *CGroupFingerprint) Fingerprint(cfg *client.Config, node *structs.Node) (bool, error) { | ||
mount, err := f.mountPointDetector.MountPoint() | ||
if err != nil { | ||
f.clearCGroupAttributes(node) | ||
return false, fmt.Errorf("Failed to discover cgroup mount point: %s", err) | ||
} | ||
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// Check if a cgroup mount point was found | ||
if mount == "" { | ||
// Clear any attributes from the previous fingerprint. | ||
f.clearCGroupAttributes(node) | ||
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if f.lastState == cgroupAvailable { | ||
f.logger.Printf("[INFO] fingerprint.cgroups: cgroups are unavailable") | ||
} | ||
f.lastState = cgroupUnavailable | ||
return true, nil | ||
} | ||
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node.Attributes["unique.cgroup.mountpoint"] = mount | ||
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if f.lastState == cgroupUnavailable { | ||
f.logger.Printf("[INFO] fingerprint.cgroups: cgroups are available") | ||
} | ||
f.lastState = cgroupAvailable | ||
return true, nil | ||
} | ||
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// clearCGroupAttributes clears any node attributes related to cgroups that might | ||
// have been set in a previous fingerprint run. | ||
func (f *CGroupFingerprint) clearCGroupAttributes(n *structs.Node) { | ||
delete(n.Attributes, "unique.cgroup.mountpoint") | ||
} | ||
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// Periodic determines the interval at which the periodic fingerprinter will run. | ||
func (f *CGroupFingerprint) Periodic() (bool, time.Duration) { | ||
return true, interval * time.Second | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,24 @@ | ||
// +build linux | ||
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package fingerprint | ||
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import ( | ||
"github.com/opencontainers/runc/libcontainer/cgroups" | ||
) | ||
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// FindCgroupMountpointDir is used to find the cgroup mount point on a Linux | ||
// system. | ||
func FindCgroupMountpointDir() (string, error) { | ||
mount, err := cgroups.FindCgroupMountpointDir() | ||
if err != nil { | ||
switch e := err.(type) { | ||
case *cgroups.NotFoundError: | ||
// It's okay if the mount point is not discovered | ||
return "", nil | ||
default: | ||
// All other errors are passed back as is | ||
return "", e | ||
} | ||
} | ||
return mount, nil | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,100 @@ | ||
package fingerprint | ||
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import ( | ||
"fmt" | ||
"testing" | ||
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"github.com/hashicorp/nomad/client/config" | ||
"github.com/hashicorp/nomad/nomad/structs" | ||
) | ||
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// A fake mount point detector that returns an empty path | ||
type MountPointDetectorNoMountPoint struct{} | ||
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func (m *MountPointDetectorNoMountPoint) MountPoint() (string, error) { | ||
return "", nil | ||
} | ||
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// A fake mount point detector that returns an error | ||
type MountPointDetectorMountPointFail struct{} | ||
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func (m *MountPointDetectorMountPointFail) MountPoint() (string, error) { | ||
return "", fmt.Errorf("cgroup mountpoint discovery failed") | ||
} | ||
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// A fake mount point detector that returns a valid path | ||
type MountPointDetectorValidMountPoint struct{} | ||
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func (m *MountPointDetectorValidMountPoint) MountPoint() (string, error) { | ||
return "/sys/fs/cgroup", nil | ||
} | ||
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// A fake mount point detector that returns an empty path | ||
type MountPointDetectorEmptyMountPoint struct{} | ||
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func (m *MountPointDetectorEmptyMountPoint) MountPoint() (string, error) { | ||
return "", nil | ||
} | ||
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func TestCGroupFingerprint(t *testing.T) { | ||
f := &CGroupFingerprint{ | ||
logger: testLogger(), | ||
lastState: cgroupUnavailable, | ||
mountPointDetector: &MountPointDetectorMountPointFail{}, | ||
} | ||
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node := &structs.Node{ | ||
Attributes: make(map[string]string), | ||
} | ||
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ok, err := f.Fingerprint(&config.Config{}, node) | ||
if err == nil { | ||
t.Fatalf("expected an error") | ||
} | ||
if ok { | ||
t.Fatalf("should not apply") | ||
} | ||
if a, ok := node.Attributes["unique.cgroup.mountpoint"]; ok { | ||
t.Fatalf("unexpected attribute found, %s", a) | ||
} | ||
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f = &CGroupFingerprint{ | ||
logger: testLogger(), | ||
lastState: cgroupUnavailable, | ||
mountPointDetector: &MountPointDetectorValidMountPoint{}, | ||
} | ||
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node = &structs.Node{ | ||
Attributes: make(map[string]string), | ||
} | ||
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ok, err = f.Fingerprint(&config.Config{}, node) | ||
if err != nil { | ||
t.Fatalf("unexpected error, %s", err) | ||
} | ||
if !ok { | ||
t.Fatalf("should apply") | ||
} | ||
assertNodeAttributeContains(t, node, "unique.cgroup.mountpoint") | ||
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f = &CGroupFingerprint{ | ||
logger: testLogger(), | ||
lastState: cgroupUnavailable, | ||
mountPointDetector: &MountPointDetectorEmptyMountPoint{}, | ||
} | ||
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node = &structs.Node{ | ||
Attributes: make(map[string]string), | ||
} | ||
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ok, err = f.Fingerprint(&config.Config{}, node) | ||
if err != nil { | ||
t.Fatalf("unexpected error, %s", err) | ||
} | ||
if !ok { | ||
t.Fatalf("should apply") | ||
} | ||
if a, ok := node.Attributes["unique.cgroup.mountpoint"]; ok { | ||
t.Fatalf("unexpected attribute found, %s", a) | ||
} | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,8 @@ | ||
// +build !linux | ||
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package fingerprint | ||
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// FindCgroupMountpointDir returns an empty path on non-Linux systems | ||
func FindCgroupMountpointDir() (string, error) { | ||
return "", nil | ||
} |
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