From 38bc1b1a310dbf5650192ea556fb909a9033dc9b Mon Sep 17 00:00:00 2001
From: Nick Ethier <nethier@hashicorp.com>
Date: Thu, 8 Apr 2021 01:03:58 -0400
Subject: [PATCH] client/fingerprint: move existing cgroup concerns to cgutil

---
 client/fingerprint/cgroup.go         |  4 +++-
 client/fingerprint/cgroup_default.go |  6 ------
 client/fingerprint/cgroup_linux.go   | 16 ----------------
 client/fingerprint/cpu_linux.go      |  6 +++++-
 drivers/exec/driver.go               |  5 +++--
 drivers/java/driver.go               |  5 +++--
 6 files changed, 14 insertions(+), 28 deletions(-)

diff --git a/client/fingerprint/cgroup.go b/client/fingerprint/cgroup.go
index b6f171782..791a6e67f 100644
--- a/client/fingerprint/cgroup.go
+++ b/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
diff --git a/client/fingerprint/cgroup_default.go b/client/fingerprint/cgroup_default.go
index 8ee17d1a1..70d68cf3c 100644
--- a/client/fingerprint/cgroup_default.go
+++ b/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
 }
diff --git a/client/fingerprint/cgroup_linux.go b/client/fingerprint/cgroup_linux.go
index 176810ed0..2bf58faac 100644
--- a/client/fingerprint/cgroup_linux.go
+++ b/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()
diff --git a/client/fingerprint/cpu_linux.go b/client/fingerprint/cpu_linux.go
index e6b78747e..a31b8e60b 100644
--- a/client/fingerprint/cpu_linux.go
+++ b/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)
 }
diff --git a/drivers/exec/driver.go b/drivers/exec/driver.go
index 1eb5d78a2..b7cfb0058 100644
--- a/drivers/exec/driver.go
+++ b/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
diff --git a/drivers/java/driver.go b/drivers/java/driver.go
index 51f7c8f54..c34888f6e 100644
--- a/drivers/java/driver.go
+++ b/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