[ClusterLabs] Antw: [EXT] Re: Q: effieciently collecting some cluster facts

[Ken Gaillot]

I think crm_mon can do nearly all of that:

* --daemonize: run continuously in the background
* --output-as: html or xml (or text with the upcoming 2.1.0 release)
* --output-to: any file name
* --include/--exclude: limit what sections are displayed, if desired
(with recent releases)
* --resource: limit resource displays to a specific resource, or a
specific set of resources that have been tagged in the CIB (with 2.0.5)

The XML output will give an abundance of information, for example about
DC and quorum:

 <current_dc present="true"
             version="2.0.5-141.2a2d6501b.git.el8-2a2d6501b"
             name="rhel8-3" id="3" with_quorum="true"/>

and about each node:

 <node name="cluster01" id="1" online="true"
       standby="false" standby_onfail="false"
       maintenance="false" pending="false" unclean="false"
       shutdown="false" expected_up="true" is_dc="false"
       resources_running="7" type="member"/>



On Thu, 2021-02-25 at 11:26 +0100, Ulrich Windl wrote:
> Thanks,
> 
> I had been expecting some magic user-level command to be used. C
> programming is probably efficient, but I#ll have to write another
> tool first.
> 
> It seems the corosync-quorumtool can also provide the information.
> Is it correct that the "ring id" has the node id of the DC?
> Like here (node id 116 is the DC):
> ------------------
> Date:             Thu Feb 25 11:24:08 2021
> Quorum provider:  corosync_votequorum
> Nodes:            3
> Node ID:          119
> Ring ID:          116/42660
> Quorate:          Yes
> 
> Regards,
> Ulrich
> 
> > > > Christine Caulfield <ccaulfie at redhat.com> schrieb am 25.02.2021
> > > > um 08:22 in
> 
> Nachricht <52d91afa-9b89-4e2e-4663-b1ded39a032e at redhat.com>:
> > The most efficient way of getting corosync facts about nodes/quorum
> > is 
> > to use the votequorum API.
> > 
> > see /usr/include/corosync/votequorum.h
> > and in the corosync sources tarball tests/testvotequorum1.c
> > 
> > CHrissie
> > 
> > 
> > On 25/02/2021 07:16, Ulrich Windl wrote:
> > > Hi!
> > > 
> > > I'm thinking about some simple cluster status display that is
> > > updated 
> > 
> > periodically.
> > > I wonder how to get some "cluster facts" efficiently. Among those
> > > are:
> > > 
> > > * Is corosync running, and how many nodes can be seen?
> > > * Is Pacemaker running, how many nodes does it see, and does it
> > > have a 
> > 
> > quorum?
> > > * Is the current node DC?
> > > * How many resources matching some regular expression are
> > > running?
> > > 
> > > Regards,
> > > Ulrich
-- 
Ken Gaillot <kgaillot at redhat.com>