[Beaker-devel] More conservative removal of implicit job sharing

Nick Coghlan ncoghlan at redhat.com
Mon Aug 26 01:56:50 UTC 2013


I've been pondering the removal of the old implicit job sharing model
from Beaker 0.15, and I'm concerned that it may break existing
installations in a way that won't be uncovered until a site upgrades to
0.15 and their users complain about not being able to update jobs any
more. At the moment, the only way for installation admins to cope with
such complaints is to roll back to 0.14 (a non-trivial exercise).

Since we don't track job activity the way we do system activity (as
described in bug 995012), installation admins also can't easily check if
their users are relying on the feature before they do the upgrade.

Accordingly, I think a slight reworking of our approach to this
deprecation may be in order:

- in 0.15, implicit job sharing remains enabled by default, but can be
switched off through a config option
- in the subsequent release, it is off by default, but the config option
can still be used to turn it back on
- only in the release after *that* (and assuming we don't have users
complaining about the "off by default" release) do we remove the feature
entirely

This change is now covered in
https://bugzilla.redhat.com/show_bug.cgi?id=1000861, and I'd like to
make that a blocker for 0.15.

I'd also like to make this our general policy for any future backwards
incompatible changes without a simple workaround:

- release N adds a config option to turn off the deprecated feature
- release N+1 changes the config option to being off by default
- release N+2 (at the earliest) actually removes the feature

Yes, it's more work for us, but I really want new Beaker releases to be
something that users look forward to, rather than something they fear as
"What did they break this time?" :)

Cheers,
Nick.

-- 
Nick Coghlan
Red Hat Infrastructure Engineering & Development, Brisbane

Testing Solutions Team Lead
Beaker Development Lead (http://beaker-project.org/)


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