Hi all, The case of automatic evacuation (or resurrection currently), is a topic which surfaces once in a while, but it isn't yet fully supported by OpenStack and/or by the cluster services. There was some attempts to bring the feature into OpenStack, however it turns out it cannot be easily integrated with. On the other hand evacuation may be executed from the outside using Nova client or Nova API calls for evacuation initiation.
I did some research regarding the ways how it could be designed, based on Russel Bryant blog post[1] as a starting point. Apart from it, I've also taken high availability and reliability into consideration when designing the solution. Together with coworker, we did first PoC[2] to enable cluster to be able to perform evacuation. The idea behind that PoC was simple - providing additional, small service which would trigger and supervise the evacuation process, which would be triggered from the outside (in this example we were using Pacemaker fencing facility, but it might be anything) using RabbitMQ directly. Those services are running on the control plane in AA fashion. That work well for us. So we started exploring other possibilities like oslo.messaging just to use it in the same manner as we did in the poc. It turns out that the implementation will not be as easy, because there is no facility in the oslo.messaging for letting sending an ACK from the client after the job is done (not as soon as it gets the message). We also looked at the existing OpenStack projects for a candidate which provide service for managing long running tasks. There is the Mistral project, which gives us almost all the features we need. The one missing feature is the HA of the Mistral tasks execution. The question is, how such problem (long running tasks) could be resolved in OpenStack? [1] http://blog.russellbryant.net/2014/10/15/openstack-instance-ha-proposal/ [2] https://github.com/dawiddeja/evacuationd -- Cheers, Roman Dobosz __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: [email protected]?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
