[openstack-dev] [glance] [nova] Glance bug with Kilo upgrade & Nova

Flavio Percoco flavio at redhat.com
Tue Jun 9 07:22:02 UTC 2015

On 09/06/15 07:09 +0000, Bhandaru, Malini K wrote:
>Flavio, would a DB script that writes an empty string or NOP or something instead of NULL In the column do the trick?
>Then the problem degenerates to a new DB upgrade script.

I now remembered about a change[0] - that I wrote myself - that required
a bump on the API version - which we did - that allows None values to
be returned in the API. This is probably what is causing this

A DB migration would certainly work, I'd love to avoid it but I guess
that's the best solution in this case.


[0] https://review.openstack.org/#/c/138184/

>-----Original Message-----
>From: Flavio Percoco [mailto:flavio at redhat.com]
>Sent: Monday, June 08, 2015 11:47 PM
>To: OpenStack Development Mailing List (not for usage questions)
>Cc: openstack-operators at lists.openstack.org
>Subject: Re: [openstack-dev] [glance] [nova] Glance bug with Kilo upgrade & Nova
>On 08/06/15 11:46 -0400, Clayton O'Neill wrote:
>>We tested testing Kilo upgrades in our hardware dev environments last
>>week and the second time through ran into this bug which right now is
>>probably a show-stopper for us.
>>The issue here is that the v1 Glance API allows you to create images
>>with properties that are 'NULL' in the Glance database.  For example:
>>    glance image-create --name cirros_test --disk-format qcow2
>>--container-format bare --file cirros-0.3.4-x86_64-disk.img --is-public
>>True --is-protected True --progress --property description=
>>It's apparently also fairly easy to end up with a NULL description when
>>editing images properties via Horizon.
>>The issue is that the v2 Glance API returns these NULL properties to
>>the client, which then validates them against the schema returned by the v2 API.
>>This schema returns specifies that the description property *must* be a string.
>>In the Kilo release, Nova has been changed to use the v2 API, so
>>suddenly this matters.  The net effect is that end users can pretty
>>easily create properties with NULL values, and then won't be able to boot instances using those images.
>>What makes this worse is that it's completely opaque to end users,
>>since this just reports that no node was available to schedule the instance.
>>However, Nova *only* uses the v2 api to list images if the
>>glance.allowed_direct_url_schemes config key is set in the config file.
>>However, this config item defaults to an empty array, meaning that by
>>default it's *always* set.  There doesn't appear to be a way to unset a
>>value with oslo-config that has a default value, blocking off that
>>route to work around the issue.  Disabling the v2 Glance API we don't
>>think will work, since Nova appears to assume the v2 API is available.
>AFAIK, Nova supports V2 image-lists since before Juno when the allowed_direct_url_schemes config option is set. Are you referring to another change? Has the default been changed in Nova? I'm asking because I was working on this migration to V2 and we decided to postpone it to L.
>>Another work around we've looked at is to change the DB schema for
>>image properties (yuck) to not allow NULL values.  This results in
>>Glance returning a
>>500 error since glance-api is attempting to insert an invalid value. 
>>This is better than instances failing in an opaque fashion, but still pretty horrible.
>>Has anyone else run into this issue yet?  Are there other work arounds
>>that we've not thought of other than "Don't create images with NULL properties?"
>>User education is definitely an option, but given the failure mode,
>>it's not a great solution for us.
>I believe this needs to be fixed in the client rather than the API and/or the schemas. I'll take a look at this right away.
>Another workaround could be updateting `schema-image.json` to add the schemas that are missing and let the client download the final schema from the V2 API.
>Keep an eye on the bug, patches coming your way (assuming what I have in mind will work).
>Flavio Percoco

Flavio Percoco
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