[ClusterLabs Developers] Impact of changing Pacemaker daemon names on other projects?

[Jan Pokorný]

On 29/03/18 11:13 -0500, Ken Gaillot wrote:
> As I'm sure you've seen, there is a strong sentiment on the users list
> to change all the Pacemaker daemon names in Pacemaker 2.0.0, mainly to
> make it easier to read the logs.
> 
> This will obviously affect any other scripts and projects that look for
> the old names. I'd like to hear more developer input on how far we
> should go with this, and how much or little of a headache it will
> cause. I'm interested in both the public projects that use pacemaker
> (crmsh, pcs, sbd, dlm, openstack) and one-off scripts that people
> commonly put together.
> 
> In order of minimum impact to maximum impact, we could actually do this
> in stages:
> 
> 1. Log tags: This hopefully wouldn't affect anyone. For example, from
> 
> Mar 12 12:10:49 [11120] node1 pacemakerd:     info:
> crm_log_init:     Changed active directory to /var/lib/pacemaker/cores
> 
> to
> 
> Mar 12 12:10:49 [11120] node1 pcmk-launchd:     info:
> crm_log_init:     Changed active directory to /var/lib/pacemaker/cores
> 
> 2. Process names: what shows up in "ps". I'm hoping this would affect
> very little outside code, so we can at least get this far.
> 
> 3. Library names: for example, -lstonithd to -lpcmk-fencing. Other
> projects would need their configure script to auto-detect which is
> available. Not difficult, but it makes all older versions of other
> projects incompatible with Pacemaker 2.0. This is mostly what I want
> feedback on, whether this is a good idea. The only advantage is
> consistency and clarity.

Good news is that pkg-config/pkgconf (PKG_CHECK_MODULES et al.
Autoconf macros) honours names of *.pc files, hence compatibility
can be maintained with symlinks.

> 4. Public API symbols: for example, crm_meta_name() ->
> pcmk_meta_name(). This would be a huge project with huge impact, and
> will definitely not be done for 2.0.0. We would immediately start using
> the new convention for new API symbols, and more slowly update existing
> ones (with compatibility wrappers for the old names).

Value added here would be putting some commitment behind the "true
public API" when the symbols get sifted carefully, leaving some other
naming prefixes reserved for private only ones (without any commitment
whatsoever).

-- 
Poki
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