swift-storage charm generates invalid fstab entry

[Mitchell Monahan]

When a swift-storage unit is configured using a path for a disk image as the 'block-device' configuration value (ie. block-device: '/var/local/swift.img|1G'), the hook fails with a message saying the 'config-changed' hook failed. After some investigation into the issue, I determined that the fstab entry being generated is invalid, causing the hook to fail with the following error (truncated to the last few lines:

  File "/var/lib/juju/agents/unit-swift-storage-1/charm/hooks/charmhelpers/core/fstab.py", line 79, in entries
    yield self._hydrate_entry(line)
  File "/var/lib/juju/agents/unit-swift-storage-1/charm/hooks/charmhelpers/core/fstab.py", line 70, in _hydrate_entry
    line.strip("\n").split()))
TypeError: __init__() takes at most 7 arguments (8 given)

After modifying the script to display the values of 'line', I see that it is generating an invalid fstab entry for the script with an extra space in it on the column for options:
/var/local/swift.img /srv/node/loop0 xfs loop, defaults 0 0

After doing a quick 'grep -nr "loop, "', I determined this is from lib/swift_storage_utils.py line 437. However, after modifying the value of the 'options' variable to be 'loop,defaults' instead of 'loop, defaults' as a temporary workaround until this was fixed upstream, I'm still getting the same generated fstab entry.

[Liam Young (gnuoy)]

Attempting to reproduce this

[Liam Young (gnuoy)]

Hi Mitchell, thanks for you bug report an analysis of the issue. I think the change you propose will fix the issue which makes me wonder whether you're also seeing Bug #1762390 ?

[Mitchell Monahan (soccermitchy)]

I'm not seeing that bug at all, unless it occurs after where I was having my issue. If it's after where the bug I found is, then I can't test it since, as I mentioned in my bug report, even after modifying that line of code I still seem to have the error that I pasted.

[Liam Young (gnuoy)]

Reproduce:
$ cat config.yaml
swift-storage:
    zone: 1
    block-device: '/var/local/swift.img|1G'

$ juju deploy --series xenial --config config.yaml \
  cs:~openstack-charmers-next/swift-storage-283

$ juju run --unit swift-storage/0 "grep swift.img /etc/fstab"
/var/local/swift.img /srv/node/loop0 xfs loop, defaults 0 0

$ juju run --unit swift-storage/0 "df -h /srv/node/loop0"
Filesystem Size Used Avail Use% Mounted on
/dev/loop1 1014M 33M 982M 4% /srv/node/loop0

$ juju run --unit swift-storage/0 "umount /srv/node/loop0"

$ juju run --unit swift-storage/0 "mount /srv/node/loop0"
mount: /etc/fstab: parse error: ignore entry at line 4.
mount: can't find /srv/node/loop0 in /etc/fstab

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/559988

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/559988
Committed: https://git.openstack.org/cgit/openstack/charm-swift-storage/commit/?id=f75bd9762ace2ed4c06eb9f12abe128749e8874b
Submitter: Zuul
Branch: master

commit f75bd9762ace2ed4c06eb9f12abe128749e8874b
Author: Liam Young <email address hidden>
Date: Tue Apr 10 10:22:16 2018 +0000

    Fix broken fstab entry

    Whitespace between the fstab option is not valid, remove it.

    Change-Id: I1be789acc7bf92811f8d4e2c0f0661ebf3be1678
    Closes-Bug: #1762105