[Kimchi-devel] [RFC] Issue 201 - Kimchi should handle libvirt connection failures

[Aline Manera]

On 04/27/2016 09:47 PM, Daniel Henrique Barboza wrote:
>
>
> On 04/26/2016 06:29 PM, Paulo Ricardo Paz Vital wrote:
>> Today, Kimchi (and Ginger) has a strong dependency with Libvirt, well 
>> described
>> in the kimchid.service.{fedora,ubuntu} file that extends the 
>> wokd.service
>> configuration to make it dependent of libvirt service. The current 
>> configuration
>> stops wokd service automatically if libvirt service is stopped.
>>
>> To prevent wokd to stop automatically if libvirt stops, a new 
>> configuration must
>> be set up and loaded, making wokd service still available to user. 
>> This is the
>> easiest part to solve this issue.
>>
>> The real issue is that most of the Kimchi operations need to connect 
>> to libvirt
>> service and the current implementation, simple stops the cherrypy 
>> server if a
>> connection is not available (after 10 seconds trying to connect), 
>> causing a
>> "502 bad gateway" error from NGINX. With this implementation from 
>> Kimchi, Wok
>> and GingerBase (and Ginger if installed) will not be available to 
>> user even
>> though they don't depend on the libvirt service.
>>
>> Basically, the proposal to solve the issue is:
>>
>> 1) Modify the kimchid.service.{fedora,ubuntu} files to "reduce" the 
>> dependency
>> on libvirt service while wokd is already running - none change will 
>> modify the
>> start up dependency; and
>>
>> 2) Modify how Kimchi handle the missing libvirt connection to no stop 
>> the
>> cherrypy server and provide information to user by Virtualization tab 
>> and its
>> sub-tabs, keeping all other plugins enabled and operating.
> Do we have a standard way in WoK to disable a plug-in? If not, this would
> be a good place to start.
>
> Note that if libvirtd service is down -> kimchi down then it would 
> make sense
> to consider libvirtd up -> kimchi up, preferably without reloading WoK
> service. Not sure if this is feasible though.
>
In case user is on Kimchi UI and libvirt goes down, IMO we should not 
reload Wok to remove Kimchi tabs, instead of that we should informe user 
through a notification that libvirt went down and Kimchi will not work 
properly.

>>
>> Feel free to make any suggestion. Patches will be submitted by the 
>> end of this
>> week.
>>
>> Thanks and best regards,
>> -- 
>> Paulo Ricardo Paz Vital
>> Linux Technology Center, IBM Systems
>> http://www.ibm.com/linux/ltc/
>>
>> _______________________________________________
>> Kimchi-devel mailing list
>> Kimchi-devel at ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/kimchi-devel
>
> _______________________________________________
> Kimchi-devel mailing list
> Kimchi-devel at ovirt.org
> http://lists.ovirt.org/mailman/listinfo/kimchi-devel
>