client/fingerprint: move existing cgroup concerns to cgutil

client/fingerprint/cgroup.go

@@ -3,6 +3,8 @@ package fingerprint
 import (
 	"time"
 
+	"github.com/hashicorp/nomad/client/lib/cgutil"
+
 	log "github.com/hashicorp/go-hclog"
 )
 
@@ -30,7 +32,7 @@ type DefaultMountPointDetector struct {
 
 // Call out to the default cgroup library
 func (b *DefaultMountPointDetector) MountPoint() (string, error) {
-	return FindCgroupMountpointDir()
+	return cgutil.FindCgroupMountpointDir()
 }
 
 // NewCGroupFingerprint returns a new cgroup fingerprinter

client/fingerprint/cgroup_default.go

@@ -2,12 +2,6 @@
 
 package fingerprint
 
-// FindCgroupMountpointDir is used to find the cgroup mount point on a Linux
-// system. Here it is a no-op implemtation
-func FindCgroupMountpointDir() (string, error) {
-	return "", nil
-}
-
 func (f *CGroupFingerprint) Fingerprint(*FingerprintRequest, *FingerprintResponse) error {
 	return nil
 }

client/fingerprint/cgroup_linux.go

@@ -4,28 +4,12 @@ package fingerprint
 
 import (
 	"fmt"
-
-	"github.com/opencontainers/runc/libcontainer/cgroups"
 )
 
 const (
 	cgroupAvailable = "available"
 )
 
-// FindCgroupMountpointDir is used to find the cgroup mount point on a Linux
-// system.
-func FindCgroupMountpointDir() (string, error) {
-	mount, err := cgroups.GetCgroupMounts(false)
-	if err != nil {
-		return "", err
-	}
-	// It's okay if the mount point is not discovered
-	if len(mount) == 0 {
-		return "", nil
-	}
-	return mount[0].Mountpoint, nil
-}
-
 // Fingerprint tries to find a valid cgroup mount point
 func (f *CGroupFingerprint) Fingerprint(req *FingerprintRequest, resp *FingerprintResponse) error {
 	mount, err := f.mountPointDetector.MountPoint()

client/fingerprint/cpu_linux.go

@@ -5,5 +5,9 @@ import (
 )
 
 func (f *CPUFingerprint) deriveReservableCores(req *FingerprintRequest) ([]uint16, error) {
-	return cgutil.GetCPUsFromCgroup(req.Config.CgroupParent)
+	parent := req.Config.CgroupParent
+	if parent == "" {
+		parent = cgutil.DefaultCgroupParent
+	}
+	return cgutil.GetCPUsFromCgroup(parent)
 }

drivers/exec/driver.go

@@ -9,9 +9,10 @@ import (
 	"sync"
 	"time"
 
+	"github.com/hashicorp/nomad/client/lib/cgutil"
+
 	"github.com/hashicorp/consul-template/signals"
 	hclog "github.com/hashicorp/go-hclog"
-	"github.com/hashicorp/nomad/client/fingerprint"
 	"github.com/hashicorp/nomad/drivers/shared/eventer"
 	"github.com/hashicorp/nomad/drivers/shared/executor"
 	"github.com/hashicorp/nomad/drivers/shared/resolvconf"
@@ -313,7 +314,7 @@ func (d *Driver) buildFingerprint() *drivers.Fingerprint {
 		return fp
 	}
 
-	mount, err := fingerprint.FindCgroupMountpointDir()
+	mount, err := cgutil.FindCgroupMountpointDir()
 	if err != nil {
 		fp.Health = drivers.HealthStateUnhealthy
 		fp.HealthDescription = drivers.NoCgroupMountMessage

drivers/java/driver.go

@@ -9,9 +9,10 @@ import (
 	"runtime"
 	"time"
 
+	"github.com/hashicorp/nomad/client/lib/cgutil"
+
 	"github.com/hashicorp/consul-template/signals"
 	hclog "github.com/hashicorp/go-hclog"
-	"github.com/hashicorp/nomad/client/fingerprint"
 	"github.com/hashicorp/nomad/drivers/shared/eventer"
 	"github.com/hashicorp/nomad/drivers/shared/executor"
 	"github.com/hashicorp/nomad/drivers/shared/resolvconf"
@@ -281,7 +282,7 @@ func (d *Driver) buildFingerprint() *drivers.Fingerprint {
 			return fp
 		}
 
-		mount, err := fingerprint.FindCgroupMountpointDir()
+		mount, err := cgutil.FindCgroupMountpointDir()
 		if err != nil {
 			fp.Health = drivers.HealthStateUnhealthy
 			fp.HealthDescription = drivers.NoCgroupMountMessage