[ClusterLabs] Detect when corosync has started

[Christine Caulfield]

On 28/08/15 16:37, Brian Campbell wrote:
> I'm running Corosync/Pacemaker on an Ubuntu derivative, and to make
> them easier to manage wrote upstart jobs to start them up rather than
> using the init scripts.
> 
> After doing so, my config scripts, which start up corosync and
> pacemaker and then configure them appropriately, start failing, I'm
> assuming because the upstart job returns slightly more quickly than
> the init scripts did. If I add a short sleep before configuring them,
> it succeeds.
> 
> However, that short sleep would make every configuration operation a
> little bit more slow, so I don't want to do that every time I
> reconfigure. I would like instead to check if corosync is functional,
> and then poll it a few times until it finishes starting if it's not
> running, rather than just unconditionally sleeping for an arbitrary
> amount of time.
> 
> Is checking the return value from "corosync-cfgtool -s" the best way
> to determine this? On systems with corosync running, it returns 0,
> while on those where it's not running, it returns 1. Is that a
> reliable way to tell if it's up and responding?
> 

That will tell you if corosync is running. What it won't tell you is if
there are any other nodes in the cluster yet - so it could still be in
the joining phase. But it's probably the best option there is at the
moment. Depending on what you actually need, using corosync-quorumtool
to determine whether the cluster has quorum might be more useful.

cman_tool in RHEL5/6 had an option to wait until the cluster was up and
(optionally) had quorum. I wonder if this might be useful for corosync?

Chrissie


> Likewise, what's the best way to tell if Pacemaker is up, and able to
> be configured? Just check the status of "crm_mon -X"? That does seem
> to return success when it's running, and failures when it's not, I
> just want to check to see if that will be reliable when it's being
> started as well.
> 
> -- Brian
> 
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