Set GCE PD attachable volume limit based on machineType

pkg/volume/gce_pd/gce_pd.go

@@ -17,10 +17,12 @@ limitations under the License.
 package gce_pd
 
 import (
+	"context"
 	"fmt"
 	"os"
 	"path"
 	"strconv"
+	"strings"
 
 	"github.com/golang/glog"
 	"k8s.io/api/core/v1"
@@ -56,6 +58,18 @@ const (
 	gcePersistentDiskPluginName = "kubernetes.io/gce-pd"
 )
 
+// The constants are used to map from the machine type (number of CPUs) to the limit of
+// persistent disks that can be attached to an instance. Please refer to gcloud doc
+// https://cloud.google.com/compute/docs/disks/#increased_persistent_disk_limits
+const (
+	OneCPU         = 1
+	EightCPUs      = 8
+	VolumeLimit16  = 16
+	VolumeLimit32  = 32
+	VolumeLimit64  = 64
+	VolumeLimit128 = 128
+)
+
 func getPath(uid types.UID, volName string, host volume.VolumeHost) string {
 	return host.GetPodVolumeDir(uid, kstrings.EscapeQualifiedNameForDisk(gcePersistentDiskPluginName), volName)
 }
@@ -104,7 +118,7 @@ func (plugin *gcePersistentDiskPlugin) GetAccessModes() []v1.PersistentVolumeAcc
 
 func (plugin *gcePersistentDiskPlugin) GetVolumeLimits() (map[string]int64, error) {
 	volumeLimits := map[string]int64{
-		util.GCEVolumeLimitKey: 16,
+		util.GCEVolumeLimitKey: VolumeLimit16,
 	}
 	cloud := plugin.host.GetCloudProvider()
 
@@ -120,6 +134,33 @@ func (plugin *gcePersistentDiskPlugin) GetVolumeLimits() (map[string]int64, erro
 		return nil, fmt.Errorf("Expected gce cloud got %s", cloud.ProviderName())
 	}
 
+	instances, ok := cloud.Instances()
+	if !ok {
+		glog.Warning("Failed to get instances from cloud provider")
+		return volumeLimits, nil
+	}
+
+	instanceType, err := instances.InstanceType(context.TODO(), plugin.host.GetNodeName())
+	if err != nil {
+		glog.Errorf("Failed to get instance type from GCE cloud provider")
+		return volumeLimits, nil
+	}
+	if strings.HasPrefix(instanceType, "n1-") {
+		splits := strings.Split(instanceType, "-")
+		if len(splits) < 3 {
+			return volumeLimits, nil
+		}
+		last := splits[2]
+		if num, err := strconv.Atoi(last); err == nil {
+			if num == OneCPU {
+				volumeLimits[util.GCEVolumeLimitKey] = VolumeLimit32
+			} else if num < EightCPUs {
+				volumeLimits[util.GCEVolumeLimitKey] = VolumeLimit64
+			} else {
+				volumeLimits[util.GCEVolumeLimitKey] = VolumeLimit128
+			}
+		}
+	}
 	return volumeLimits, nil
 }