[ClusterLabs Developers] If anybody develops against libpe_status.so: skipped soname bump (Was: Pacemaker 2.0.2 final release now available)

[Jan Pokorný]

On 14/06/19 14:56 -0500, Ken Gaillot wrote:
> On Fri, 2019-06-14 at 20:13 +0200, Jan Pokorný wrote:
>>> On Thu, 2019-06-06 at 10:12 -0500, Ken Gaillot wrote:
>>> 
>>> Source code for the Pacemaker 2.0.2 and 1.1.21 releases is now
>>> available:
>>> 
>>> 
> https://github.com/ClusterLabs/pacemaker/releases/tag/Pacemaker-2.0.2
>>> 
>>> 
> https://github.com/ClusterLabs/pacemaker/releases/tag/Pacemaker-1.1.21
>> 
>> In retrospect (I know, everybody is a general once the battle is
>> over), called out for with some automated tests in Fedora, there were
>> some slight discrepancies -- depending on whether any external
>> clients
>> of particular "wannabe internal" libraries of pacemaker accompanied
>> with "wannabe internal" headers, none of which are marked so
>> expressly
>> (and in case of headers, are usually shipped in dev packages anyway).
> 
> All public API is documented:
> 
>   https://clusterlabs.org/pacemaker/doxygen/
> 
> Anything not documented there is private API.

It's rather simplistic (and hypocritical) view not being part of any
written "contract", isn't it? :-)

> remote.h should be in noinst_HEADERS, thanks for catching that. It
> would also be a good idea to put "_internal" in all internal
> headers' names to be absolutely clear; most of them already have it.

Yes, that was that surprising moment here.

>> For the piece of mind, I am detailing the respective library that
>> would likely have been eligible for an explicit soname bump and why.
>> If you feel affected, please speak up so we have a clear incentive to
>> publish a "hotfix" for downstreams and direct consumers, otherwise
>> at least I don't feel compelled to anything immediate beyond this
>> FYI,
>> and we shall rather do it in 2.0.3 even if not otherwise justified
>> with an inter-release delta, so there isn't a tiniest glitch possible
>> when 2.0.2 is skipped on the upgrade path (which is generally not
>> recommended but would be understandable if you happen to rely on
>> those very libpe_status.so ABI details).
>> 
>> The mentioned ABI changes are:
>> 
>> * libpe_status.so.28.0.2 (2.0.1: soname 28.0.1)
>>   - include/crm/pengine/remote.h: function renames, symbolic notation:
>>     { -> pe__}{is_baremetal_remote_node -> is_remote_node,
>>                is_container_remote_node -> is_guest_node,
>>                is_remote_node -> is_guest_or_remote_node,
>>                is_rsc_baremetal_remote_node -> resource_is_remote_conn,
>>                rsc_contains_remote_node -> resource_contains_guest_node}
>> 
>> (all other ABI breaking changes appear self-contained for not
>> being related to anything exposed through what could be considered
>> a public header/API -- not to be confused with ABI)
> 
> Since those functions are internal API, we don't need a soname bump.
> Distributing the header was a mistake and should not be considered
> making it public API. The only functions in there that had doxygen
> blocks were marked internal, so that helps.
> 
> As an aside, the entire libpe_status was undocumented until 2.0.1,
> but that was an oversight (a missing \file line).

In FOSS, (un)documentation aspect doesn't play that much of a role...

> In practice there were some projects that used it, and we did bump
> the soname for most functions. Now however it's documented properly,
> so the line should be clear.

Not at all, see above.

Traces of the pre-existing mess have some momentum.

Anyway, good to know the root cause, question is how to deal with
the still real fallout.

>> Note that there's at least a single publicly known consumer of
>> libpe_status.so, but luckily, sbd only uses some unaffected pe_*
>> functions.  Said after-the-fact bump of said library would require
>> it to be rebuilt as well (and all the SW that'd be in the same
>> boat), so even less appealing to do that now, but note that
>> such rebuild will be needed with said planned bump for 2.0.3.
>> 
>> But perhaps, some other changes as announced in [1] will be faster
>> than that -- to that account, I'd note that perhaps applying
>> single source -> multiple binary copies of code scheme is not all
>> that bad and we could move some of shared internal only code into
>> static libraries subsequently used to feed the links from the
>> actual daemons/tools code objects -- or the private libraries
>> shall at least be factually privatized/unshared, i.e., put into
>> a private, non-standard location (this is what, e.g., systemd uses)
>> where only "accustomed" executables can find them.
>> 
>> [1]https://lists.clusterlabs.org/pipermail/developers/2019-February/001358.html

-- 
Jan (Poki)
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