cloud-init fails to grow disk on physical servers with multipath.

This bug was originally filed in Launchpad as [LP: #1556260](https://bugs.launchpad.net/cloud-init/+bug/1556260)

Launchpad details

affected_projects = ['cloud-init (Ubuntu)']

assignee = None

assignee_name = None

date_closed = None

date_created = 2016-03-11T19:44:11.969495+00:00

date_fix_committed = None

date_fix_released = None

id = 1556260

importance = medium

is_complete = False

lp_url = https://bugs.launchpad.net/cloud-init/+bug/1556260

milestone = None

owner = jinendra

owner_name = jinendra

private = False

status = triaged

submitter = jinendra

submitter_name = jinendra

tags = []

duplicates = []

_Launchpad user **jinendra(jinendra)** wrote on 2016-03-11T19:44:11.969495+00:00_

for provisioning ubuntu trusty on baremetal, cloud-init fails to grow root partition, below is the error.
physical server is HP bl460c blade , booting from SAN and using multipath ,

====================================
- cc_growpart.py[DEBUG]: No 'growpart' entry in cfg. Using default: {'ignore_growroot_disabled': False, 'mode': 'auto', 'devices': ['/']}
- util.py[DEBUG]: Running command ['growpart', '--help'] with allowed return codes [0] (shell=False, capture=True)
- util.py[DEBUG]: Reading from /proc/1005/mountinfo (quiet=False)
- util.py[DEBUG]: Read 1121 bytes from /proc/1005/mountinfo
- util.py[DEBUG]: resize_devices took 0.003 seconds
- cc_growpart.py[DEBUG]: '/' SKIPPED: device_part_info(/dev/disk/by-label/cloudimg-rootfs) failed: /dev/disk/by-label/cloudimg-rootfs not a partition
====================================

upon checking seems like cc_growpart.py script is relying on "/sys/class/block/device-name/partition" file to check number of partitions.

but for dm multipath devices , there is no such "partition" attribute exists, hence script error out saying "not a partition".

I do not have any solution for now, but trying to find how to map multipath device like /dev/dm-1 to it's real scsi disk /dev/sda1 .. if that's figured out then we can put some logic to say if base name is dm-x then find mapped sdx and use that device to find a partition etc.

is this just me or someone else also has this issue with cloud-init failing on multipath disks.