On 07/20/2016 11:47 AM, Adam Spiers wrote: > Ken Gaillot <kgail...@redhat.com> wrote: >> Hello all, >> >> I've been meaning to address the implementation of "reload" in Pacemaker >> for a while now, and I think the next release will be a good time, as it >> seems to be coming up more frequently. > > [snipped] > > I don't want to comment directly on any of the excellent points which > have been raised in this thread, but it seems like a good time to make > a plea for easier reload / restart of individual instances of cloned > services, one node at a time. Currently, if nodes are all managed by > a configuration management system (such as Chef in our case), when the > system wants to perform a configuration run on that node (e.g. when > updating a service's configuration file from a template), it is > necessary to place the entire node in maintenance mode before > reloading or restarting that service on that node. It works OK, but > can result in ugly effects such as the node getting stuck in > maintenance mode if the chef-client run failed, without any easy way > to track down the original cause. > > I went through several design iterations before settling on this > approach, and they are detailed in a lengthy comment here, which may > help you better understand the challenges we encountered: > > > https://github.com/crowbar/crowbar-ha/blob/master/chef/cookbooks/crowbar-pacemaker/providers/service.rb#L61
Wow, that is a lot of hard-earned wisdom. :-) I don't think the problem is restarting individual clone instances. You can already restart an individual clone instance, by unmanaging the resource and disabling any monitors on it, then using crm_resource --force-* on the desired node. The problem (for your use case) is that is-managed is cluster-wide for the given resource. I suspect coming up with a per-node interface/implementation for is-managed would be difficult. If we implement --force-reload, there won't be a problem with reloads, since unmanaging shouldn't be necessary. FYI, maintenance mode is supported for Pacemaker Remote nodes as of 1.1.13. > Similar challenges are posed during upgrade of Pacemaker-managed > OpenStack infrastructure. > > Cheers, > Adam > > _______________________________________________ > Users mailing list: Users@clusterlabs.org > http://clusterlabs.org/mailman/listinfo/users > > Project Home: http://www.clusterlabs.org > Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf > Bugs: http://bugs.clusterlabs.org > _______________________________________________ Users mailing list: Users@clusterlabs.org http://clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org