From e4dc6709de8ab20717d4d6b1b4868159ad729ebe Mon Sep 17 00:00:00 2001
From: Jan Safranek <jsafrane@redhat.com>
Date: Wed, 23 Mar 2016 12:07:16 +0100
Subject: [PATCH] Remove limit of attached AWS devices from kubelet.

Limit of nr. of attached EBS volumes to a node is now enforced by scheduler. It
can be adjusted by KUBE_MAX_PD_VOLS env. variable there.

Therefore we don't need the same check in kubelet. If the system admin wants to
attach more, we should allow it.

Kubelet limit is now 650 attached volumes ('ba'..'zz').
---
 pkg/cloudprovider/providers/aws/aws.go | 36 +++++++-------------------
 1 file changed, 10 insertions(+), 26 deletions(-)

diff --git a/pkg/cloudprovider/providers/aws/aws.go b/pkg/cloudprovider/providers/aws/aws.go
index 9db23bb61d..b1003bb49d 100644
--- a/pkg/cloudprovider/providers/aws/aws.go
+++ b/pkg/cloudprovider/providers/aws/aws.go
@@ -904,23 +904,6 @@ type awsInstanceType struct {
 // This should be stored as a single letter (i.e. c, not sdc or /dev/sdc)
 type mountDevice string
 
-// TODO: Also return number of mounts allowed?
-func (self *awsInstanceType) getEBSMountDevices() []mountDevice {
-	// See: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/block-device-mapping-concepts.html
-	// We will generate "ba", "bb", "bc"..."bz", "ca", ..., up to DefaultMaxEBSVolumes
-	devices := []mountDevice{}
-	count := 0
-	for first := 'b'; count < DefaultMaxEBSVolumes; first++ {
-		for second := 'a'; count < DefaultMaxEBSVolumes && second <= 'z'; second++ {
-			device := mountDevice(fmt.Sprintf("%c%c", first, second))
-			devices = append(devices, device)
-			count++
-		}
-	}
-
-	return devices
-}
-
 type awsInstance struct {
 	ec2 EC2
 
@@ -1050,19 +1033,20 @@ func (self *awsInstance) getMountDevice(volumeID string, assign bool) (assigned
 		return mountDevice(""), false, nil
 	}
 
-	// Check all the valid mountpoints to see if any of them are free
-	valid := instanceType.getEBSMountDevices()
-	chosen := mountDevice("")
-	for _, mountDevice := range valid {
-		_, found := deviceMappings[mountDevice]
-		if !found {
-			chosen = mountDevice
-			break
+	// Find the first unused device in sequence 'ba', 'bb', 'bc', ... 'bz', 'ca', ... 'zz'
+	var chosen mountDevice
+	for first := 'b'; first <= 'z' && chosen == ""; first++ {
+		for second := 'a'; second <= 'z' && chosen == ""; second++ {
+			candidate := mountDevice(fmt.Sprintf("%c%c", first, second))
+			if _, found := deviceMappings[candidate]; !found {
+				chosen = candidate
+				break
+			}
 		}
 	}
 
 	if chosen == "" {
-		glog.Warningf("Could not assign a mount device (all in use?).  mappings=%v, valid=%v", deviceMappings, valid)
+		glog.Warningf("Could not assign a mount device (all in use?).  mappings=%v", deviceMappings)
 		return "", false, fmt.Errorf("Too many EBS volumes attached to node %s.", self.nodeName)
 	}