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

[Paulo Ricardo Paz Vital]

On Apr 27 09:47PM, 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.
>

Not yet, but Trujillo is working in a task to enable/disable any Wok plugin.
For now and based on my preliminary tests, Kimchi plugin can continue be loaded
and when libvirtd service is up again, it's able to connect and continue to
work as normal.

> 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.
>

My proposal will make wokd not down if libvirtd goes down, but if wokd is down
will always check if libvirtd is up, and if not will up it. At least, that was
I got from my preliminary tests. 

> >
> >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
>

--
Paulo Ricardo Paz Vital
Linux Technology Center, IBM Systems
http://www.ibm.com/linux/ltc/