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[Bug 1771382] [NEW] ds-identify caches errors

To: yahoo-eng-team@xxxxxxxxxxxxxxxxxxx
From: MartinSteigerwald <martin.steigerwald@xxxxxxxxx>
Date: Tue, 15 May 2018 15:37:38 -0000
Reply-to: Bug 1771382 <1771382@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx

Public bug reported:

cloud-init 18.2 from
http://download.opensuse.org/repositories/Cloud:/Tools/SLE_12_SP3/ on
SLES 12 SP 3 with NoCloud data source via Cloud Init drive made by
Proxmox.

On SLES 12 SP3 NoCloud data source was not working, despite

slestemplate:~ # blkid -c /dev/null -o export
[…]
DEVNAME=/dev/sr0
UUID=2018-05-15-16-34-27-00
LABEL=cidata
TYPE=iso9660
[…]

with necessary files on it. blkid gives 0 as returncode

Why?

I only kept parts of the output:

slestemplate:/etc/cloud # cat /run/cloud-init/ds-identify.log
[up 8.63s] ds-identify
policy loaded: mode=search report=false found=all maybe=all notfound=disabled
no datasource_list found, using default: MAAS ConfigDrive NoCloud AltCloud Azure Bigstep CloudSigma CloudStack DigitalOcean AliYun Ec2 GCE OpenNebula OpenStack OVF SmartOS Scaleway Hetzner IBMCloud
ERROR: failed running [127]: blkid -c /dev/null -o export
[…]
FS_LABELS=unavailable:error
ISO9660_DEVS=unavailable:error

It might have been that I did not yet add the CloudInit drive in Proxmox
yet.

A subsequent call to

slestemplate:~ # /usr/lib/cloud-init/ds-identify

did not yet yield a different result.

Only by analysing the source I found that it caches results and I can
use the `--force` option to override this. I did this and the NoCloud
datasource got detected properly. Apparently this is cached now.

The tool would only inform of the caching as a DEBUG message. However I
set logging to INFO for all parts of Cloud Init as the FileHandler
clutters the log with tons of messages how many bytes it read from each
file. Sure, I could use INFO only for FileHandler.

Several issues reduce the ease of administration here:

1. Don´t cache errors. Really… just… don´t.

2. Don´t cache errors almost *silently* (just as a debug message).

3. Decide wisely what is a debug message and what is not.

4. A search for `ds-identify` in the documentation available at
https://cloudinit.readthedocs.io/en/latest/ did not yield any result.

5. And in general: Keep it short and simple.

IMHO the first is the most important: Don´t cache errors. If the
resource now is there, recognize it, without further discussion.

** Affects: cloud-init
Importance: Undecided
Status: New

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https://bugs.launchpad.net/bugs/1771382

Title:
ds-identify caches errors

Status in cloud-init:
New

Bug description:
cloud-init 18.2 from
http://download.opensuse.org/repositories/Cloud:/Tools/SLE_12_SP3/ on
SLES 12 SP 3 with NoCloud data source via Cloud Init drive made by
Proxmox.