cloud-init: Attempt to mkswap on a partition fails: invalid block count argument: ''

[Graham Leggett]

If an attempt is made to configure a swap partition on an Ubuntu Bionic machine as follows (not a swap file, a swap partition), the attempt to mkswap fails.

The expected behaviour is that mkswap and swapon are executed correctly, and /dev/xvdg becomes a valid swap disk. In addition, when filename points at a partition, size and maxsize should be ignored.

fs_setup:
  - label: vidi
    device: /dev/xvde
    filesystem: ext4
  - label: swap
    device: /dev/xvdg
    filesystem: swap
mounts:
- [ /dev/xvde, /var/lib/vidispine, ext4, defaults, 0, 0 ]
- [ /dev/xvdg, none, swap, sw, 0, 0 ]
swap:
    filename: /dev/xvdg
    size: auto
    maxsize: 17179869184
mount_default_fields: [ None, None, "auto", "defaults", "0", "2" ]

When the machine starts up for the first time, the following error is logged after the swap size parameter is passed as the empty string:

2020-02-07 20:21:55,242 - cc_disk_setup.py[WARNING]: Force flag for swap is unknown.
2020-02-07 20:21:55,255 - util.py[WARNING]: Failed during filesystem operation
Failed to exec of '['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']':
Unexpected error while running command.
Command: ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']
Exit code: 1
Reason: -
Stdout:
Stderr: mkswap: invalid block count argument: ''
2020-02-07 20:21:55,530 - cc_mounts.py[WARNING]: Activate mounts: FAIL:swapon -a
2020-02-07 20:21:55,530 - util.py[WARNING]: Activate mounts: FAIL:swapon -a

[Chad Smith (chad.smith)]

Please attach the tarfile of cloud-init collect-logs. and mention the version of cloud-init that is running.

[Graham Leggett (minfrin)]

Version is 19.4-33-gbb4131a2-0ubuntu1~18.04.1 from Ubuntu Bionic.

The full log is as follows:

2020-02-07 21:00:18,780 - cc_disk_setup.py[DEBUG]: Creating new filesystem.
2020-02-07 21:00:18,780 - util.py[DEBUG]: Running command ['udevadm', 'settle'] with allowed return codes [0] (shell=False, capture=True)
2020-02-07 21:00:18,798 - cc_disk_setup.py[DEBUG]: Checking /dev/xvdg against default devices
2020-02-07 21:00:18,798 - cc_disk_setup.py[DEBUG]: Identifying device to create swap filesytem on
2020-02-07 21:00:18,798 - util.py[DEBUG]: Running command ['/bin/lsblk', '--pairs', '--output', 'NAME,TYPE,FSTYPE,LABEL', '/dev/xvdg'] with allowed return codes [0] (shel
l=False, capture=True)
2020-02-07 21:00:18,802 - cc_disk_setup.py[DEBUG]: Automatic device for /dev/xvdg identified as /dev/xvdg
2020-02-07 21:00:18,802 - cc_disk_setup.py[DEBUG]: File system type 'swap' with label 'swap' will be created on /dev/xvdg
2020-02-07 21:00:18,803 - util.py[DEBUG]: Running command ['/bin/lsblk', '--pairs', '--output', 'NAME,TYPE,FSTYPE,LABEL', '/dev/xvdg', '--nodeps'] with allowed return cod
es [0] (shell=False, capture=True)
2020-02-07 21:00:18,806 - cc_disk_setup.py[WARNING]: Force flag for swap is unknown.
2020-02-07 21:00:18,806 - cc_disk_setup.py[DEBUG]: Creating file system swap on /dev/xvdg
2020-02-07 21:00:18,806 - cc_disk_setup.py[DEBUG]: Using cmd: ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']
2020-02-07 21:00:18,806 - util.py[DEBUG]: Running command ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', ''] with allowed return codes [0] (shell=False, capture=True)
2020-02-07 21:00:18,817 - util.py[DEBUG]: Creating fs for /dev/xvdg took 0.037 seconds
2020-02-07 21:00:18,817 - util.py[WARNING]: Failed during filesystem operation
Failed to exec of '['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']':
Unexpected error while running command.
Command: ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']
Exit code: 1
Reason: -
Stdout:
Stderr: mkswap: invalid block count argument: ''
2020-02-07 21:00:18,822 - util.py[DEBUG]: Failed during filesystem operation
Failed to exec of '['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']':
Unexpected error while running command.
Command: ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']
Exit code: 1
Reason: -
Stdout:
Stderr: mkswap: invalid block count argument: ''
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/cloudinit/config/cc_disk_setup.py", line 994, in mkfs
    util.subp(fs_cmd, shell=shell)
  File "/usr/lib/python3/dist-packages/cloudinit/util.py", line 2065, in subp
    cmd=args)
cloudinit.util.ProcessExecutionError: Unexpected error while running command.
Command: ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']
Exit code: 1
Reason: -
Stdout:
Stderr: mkswap: invalid block count argument: ''

[Ryan Harper (raharper)]

Could you please attach the tarball created from running:

cloud-init collect-logs

This collects all of the cloud-init metadata and logs that are used during boot; that way we don't have to keep asking for additional logs from different places.

[Graham Leggett (minfrin)]

Looks like this bug was fixed in https://github.com/canonical/cloud-init/pull/143

[Ryan Harper (raharper)]

With some more debugging, the base image was older than when this fix went into upstream

https://github.com/canonical/cloud-init/pull/143/files

On current images, the following cloud-config is successful (I removed the swap: config):

#cloud-config
fs_setup:
  - label: vidi
    device: /dev/vdb
    filesystem: ext4
  - label: swap
    device: /dev/vdc
    filesystem: swap

mounts:
- [ /dev/vdb, /var/lib/vidispine, ext4, defaults, 0, 0 ]
- [ /dev/vdc, none, swap, sw, 0, 0 ]

mount_default_fields: [ None, None, "auto", "defaults", "0", "2" ]

----

ubuntu@test-mkswap:~$ cat /etc/fstab
LABEL=cloudimg-rootfs / ext4 defaults 0 0
LABEL=UEFI /boot/efi vfat defaults 0 0
/dev/vdb /var/lib/vidispine ext4 defaults,comment=cloudconfig 0 0
/dev/vdc none swap sw,comment=cloudconfig 0 0
ubuntu@test-mkswap:~$ cat /proc/swaps
Filename Type Size Used Priority
/dev/vdc partition 41943036 0 -2
ubuntu@test-mkswap:~$ grep mkswap /var/log/cloud-init.log
2020-02-07 21:42:01,154 - cc_set_hostname.py[DEBUG]: Setting the hostname to test-mkswap.novalocal (test-mkswap)
2020-02-07 21:42:01,155 - __init__.py[DEBUG]: Non-persistently setting the system hostname to test-mkswap
2020-02-07 21:42:01,155 - util.py[DEBUG]: Running command ['hostname', 'test-mkswap'] with allowed return codes [0] (shell=False, capture=True)
2020-02-07 21:42:04,373 - cc_disk_setup.py[DEBUG]: Using cmd: ['/sbin/mkswap', '/dev/vdc', '-L', 'swap']
2020-02-07 21:42:04,373 - util.py[DEBUG]: Running command ['/sbin/mkswap', '/dev/vdc', '-L', 'swap'] with allowed return codes [0] (shell=False, capture=True)
2020-02-07 21:42:04,712 - cc_update_hostname.py[DEBUG]: Updating hostname to test-mkswap.novalocal (test-mkswap)
2020-02-07 21:42:04,712 - __init__.py[DEBUG]: Attempting to update hostname to test-mkswap in 1 files

[Ryan Harper (raharper)]

<minfrin> The machine I'm working on uses cloud-init to update itself, it might only have the fix after the updates.
<rharper> ah, interesting
<rharper> cat /etc/cloud/build.info
<rharper> that'll give us a point in time for which version you have
<rharper> and I suspect you're right, the top of your cloud-init.log will the original version
<minfrin> build_name: serverserial: 20190514
<minfrin> Definitely way older than the PR.
<rharper> yep
<minfrin> I suspect the fix in our case is to use the latest image of Ubuntu from end Jan 2020.
<rharper> yep

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/3605