[ClusterLabs] Resource agents differences from 1.1.14 and 1.1.18

[Salvatore D'angelo]

Hi, thanks for reply

> On 21 Jun 2018, at 15:09, Jan Pokorný <jpokorny at redhat.com> wrote:
> 
> Hello Salvatore,
> 
> On 21/06/18 12:44 +0200, Salvatore D'angelo wrote:
>> I am trying to upgrade my PostgresSQL cluster managed by pacemaker
>> to pacemaker 1.1.8 or 2.0.0.  I have some resource agents that I
>> patched to have them working with my cluster.
>> 
>> Can someone tell me if something is changed in the OCF interface
>> from 1.1.14 release and the 1.1.8/2.0.0?
> 
> You can consider the OCF specification/interface stable and no
> breakages are really imminent.

Good to know

>  There are admittedly some parts with
> less than well-defined semantics (if it's defined at all; for instance,
> questions on what's the proper interpretation of "unique" slash
> reloadable parameters was raised in the past [1,2]).
> 
> This stability is moreover enforced with the requirement of cross
> compatibility between various OCF conformant agent vs. resource
> manager implementations (say those maintained in resource-agents
> project vs. pacemaker, plus various versions thereof, without any
> apriori defined ways of how to negotiate any further inteface
> specifics, but see [3], for instance).
> 
>> I am using the following resource agents:
>> 
>> /usr/lib/ocf/resource.d/heartbeat/Filesystem
>> /usr/lib/ocf/resource.d/heartbeat/ethmonitor
>> /usr/lib/ocf/resource.d/heartbeat/pgsql (patched)
> 
> ^ this is really contained within resource-agents project, and as
>  mentioned, nothing pushes you to update this piece of software
>  even if you intend to update pacemaker (granted, keeping step
>  with overall evolutionary "time snapshots" is always wise)
> 
>> /usr/lib/ocf/resource.d/pacemaker/HealthCPU (patched)
>> /usr/lib/ocf/resource.d/pacemaker/ping (patched)
>> /usr/lib/ocf/resource.d/pacemaker/SysInfo (patched)
> 
> ^ and these are from pacemaker's realms, so there's naturally
>  a closer coupling possibly beyond what standard mandates, but
>  again, OCF forms a "fixed point", basis upon which the graph
>  connecting the functionality user(s) and providers is formed,
>  so presumably you can mix and match various versions even if
>  the bits come from the very same project
> 
>> I am doing some tests to verify this but I would like to know if
>> there is at high level something I should be aware.
> 
> Nothing comes to my mind, though your are always best served with
> your own investigation (since you are modifying the agents anyway).
> 
> As a rule of thumb, I'd start with checking the changelogs of the
> mentioned projects, and deeper concerns can ultimately be resolved
> with the review of cross-version changes on the source code level,
> e.g.:
> 
>  git clone https://github.com/ClusterLabs/resource-agents.git
>  pushd resource-agents
>  # let's say you start with agents from v3.9.7 release
>  git diff v3.9.7 v4.1.1 -- heartbeat/{Filesystem,ethmonitor,pgsql}
>  popd
> 
>  git clone https://github.com/ClusterLabs/pacemaker.git
>  pushd pacemaker
>  git diff Pacemaker-1.1.14 Pacemaker-1.1.18 -- \
>      extra/resources/{HealthCPU,SysInfo,ping}
>  popd
> 
> It's more like showing how to fish than serving you a meal,
> but hopefully this helps regardless (perhaps even more than
> latter would do).
> 

Yes, that’s exactly what I did. I just double checked.

> 
> [1] https://lists.clusterlabs.org/pipermail/users/2016-June/010635.html
> [2] https://lists.clusterlabs.org/pipermail/users/2017-September/013743.html
> [3] https://github.com/ClusterLabs/OCF-spec/issues/17
> 
> -- 
> Jan (Poki)
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