Upgrade Erlang to 26.0
The RabbitMQ cluster currently runs on Erlang 25 enforced via a version lock to prevent compatibility problems on unexpected Erlang upgrade. With the pending release of RabbitMQ 3.13 [1], only Erlang 26 is going to be supported.
When naively upgrading a node to Erlang 26, the node cannot join the cluster afterwards. This might be caused by some SSL layer peer verification stuff which has always been a bit problematic.
Something like cki-tools#123 might make it possible to do a complete cluster replacement, but normally that should not be necessary.
AC:
-
prevent unplanned upgrade to RabbitMQ 3.13 -
follow https://cki-project.org/docs/cki/operations/upgrade-rabbitmq/ to upgrade the Erlang version to 26.0, and fix any resulting problems
[1] https://github.com/rabbitmq/rabbitmq-server/releases/tag/v3.13.0-rc.4
Edited by Michael Hofmann