Hi Stackers!

I would like to sync about the planned timeline of dropping eventlet
support from OpenStack / Oslo.

Nova definitely needs at least the full 2026.1 cycle to have a chance
to transform the nova-compute service. But this plan already feels
stretched based on the progress in the current cycle. So being
conservative means we need the 2026.2 cycle as a buffer.

Nova would like to keep a release where we support both eventlet and
threading in parallel. So that operators can do the switching from
eventlet to threading outside of the upgrade procedure. (This was an
explicit request from them during the PTG). So 2026.2 could be that
version where nova fully supports both concurrency mode, while
eventlet can be marked deprecated. Then the 2027.1 release could be
the first release dropping eventlet.

However we need to align with the SLURP upgrade as well. 2026.1 is a
SLURP. But in that release Nova might not be ready to have all
services running in threading mode. So the 2026.1 - 2027.1 SLURP
upgrade would force the operators to change the concurrency mode
during the upgrade itself.

I see two ways forward:
* A) We say that operators who want to do the concurrency mode change
outside of an upgrade could not skip the 2026.2 release, i.e. they
cannot do SLURP directly from 2026.1. to 2027.1.
* B) We keep supporting the eventlet mode in the 2027.1 release as
well and only dropping support in 2028.1.

What do you think?

Cheers
gibi