On 11/11/2013 11:48 AM, Mike Kolesnik wrote:
----- Original Message -----
Hi Mike,
----- Original Message -----
From: "Mike Kolesnik" <mkole...@redhat.com>
To: "engine-devel" <engine-devel@ovirt.org>
Cc: "Barak Azulay" <bazu...@redhat.com>, "Martin Perina"
<mper...@redhat.com>, "Livnat Peer" <lp...@redhat.com>,
"Itamar Heim" <ih...@redhat.com>
Sent: Monday, November 11, 2013 8:49:33 AM
Subject: Custom properties per device + vNIC profile = not working (< 3.3)
Hi,
I came across a situation where I wanted to define custom properties on a
vNIC profile sitting under a network in a 3.2 data center.
From what I saw the configuration value for custom properties
(CustomDeviceProperties) is split into 4, one per each version (3.0, 3.1,
3.2, 3.3).
Since vNIC profile is located under the DC tree, it takes the DC version -
3.2 in this specific case.
Custom Device Properties were designed to be specified for each cluster
version
independently, it doesn't care about DC version. AFAIK cluster version
defines
what features are available ...
I tried to set the config value for 3.2 but got:
$ engine-config -s
CustomDeviceProperties="{type=interface;prop={myProp=[a-zA-Z0-9-]+}}"
--cver=3.2
Cannot set value {type=interface;prop={myProp=[a-zA-Z0-9-]+}} to key
CustomDeviceProperties. Device custom properties are not supported in
version 3.2
This is already not very good, since in a 3.2 DC there can be 3.3 clusters
with 3.3 hosts that do support custom device properties.
Specify your properties for 3.3 version, since they will be used in 3.3
clusters ...
But the effective version is the DC version as I explained.
In a DC 3.0-3.3 I can have clusters which the minimal version is the DC
version, and the maximal version is 3.3.
For example I can have the following:
DC - version 3.0
+ Cluster 1 - version 3.0
+ Cluster 2 - version 3.1
+ Cluster 3 - version 3.2
+ Cluster 4 - version 3.3
In this constellation, I could use custom device properties only on Cluster 4,
but it's not possible to define them since the vNIC profile is using the DC
version 3.0.
So effectively this feature is not usable to me unless I use a 3.3 DC.
I also tried to alter the config value in the DB directly, but the custom
properties code ignored it since custom properties are not supported in
3.2.
So, de facto, I have no reasonable way as a user to define custom device
properties to use for my vNIC profiles in DC < 3.3.
There are two configuration properties for Custom Device Properties:
1) SupportCustomDeviceProperties
- defines in what version properties are supported
- cannot be altered by users of course
2) CustomDeviceProperties
- holds properties specification for each version
- can be defined using engine-config
I opened the bug https://bugzilla.redhat.com/show_bug.cgi?id=1028757 for
this, however I also want to discuss the situation:
I looked at the bug and the problem is, that management network profile
is bound to DC and not the Cluster. And that's something we never thought of
...
1. As a user, I can't set custom properties for level < 3.3 which is not
good.
Well, it's 3.3 feature, so it looks OK for me
Removing the blocking, and loading custom properties for all versions would
fix the bug and allow using custom device properties for older versions,
the
reasonable place to block this would be running a VM (or plugging a
device).
Basically this is the lesser issue..
2. I just don't see the added value of splitting the definition of the
properties per level..
The idea behind the version splitting was:
1) We have a device with a feature that doesn't work correctly with version
3.3,
but it's fixed in 3.4
2) By specifying custom property per version we cane disable this feature for
3.3
and enable for 3.4
Custom properties is not for specifying which features are enabled, there is a
whole other mechanism for that..
Custom properties is for hooks (and other possible extensions), which by
definition are not something that is guaranteed to exist so I see no point to
force the user to update multiple configurations and cause confusion for him..
as martin explained, we have predefined custom properties, which are
based on the vdsm version, and hence are actually features we know to
expose or not to expose.
user-defined custom properties - are up to the admin, but we let these
be at cluster level as well to allow more granularity.
The custom properties are extensions which might or might not be available
to
a certain VM, I don't see how having different sets of custom properties
per
version (what version, DC version, cluster version?) would make any
difference - either the VM can utilize the extension given some state of
the
system, or it can't, but the determining factor is not the version but
rather the availability of the extension.
For example, I can have a hook for vNIC altering some property installed on
host A and not host B, if the VM runs on host A it will get this capability
and on host B it won't, regardless the DC version the VM is in.
This is not to say we shouldn't block custom properties on the engine-VDSM
API level since it's only available since 3.3, but this is handled by
another config value (SupportCustomDeviceProperties) which is not alterable
by the user.
So basically, I think splitting the value per version is over complication
and see no added value to the users, just more maintenance should they
choose to use this feature.
Your thoughts please.
AFAIK only network and storage team wanted to use device custom properties
in 3.3 version, but I'm not sure what's current usage status.
But IMHO it's too late for 3.3 to change specification ...
Since I can have cluster 3.3 in a DC < 3.3, and this is the upgrade path for
existing users,
I'd argue that the bug is severe enough and should be fixed asap even for 3.3
versions.
please note that if you expose this at cluster level and not DC level,
you need to make sure to verify it when moving a VM between clusters in
same DC.
also, if this is somehow related to logical networks, not vnic specific,
than logical networks are DC level entities.
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