Hello @seh,
Thanks for posting, and apologies for the long wait time on a response. We recently had another topic on the Consul Primary DC. @mkeeler posted here: Does/should the primary datacenter ever change? - #5 by mkeeler
Not only should you not need to account for the primary DC changing but many features of Consul rely on having a stable primary DC. For example, Consul’s ACL system will perform all writes (except for DC local tokens) within the primary DC and then replicate the data out to all the other datacenters. The primary DC is the source of truth for ACL policies, roles etc. If you were to manually change your primary datacenter configuration after setting all of this up, lots of things would stop working. It might in theory be possible to change your primary DC but this would require a lot of coordination and planning and is not something you should ever hope to do.
In short - when identifying DC’s, be sure to select a location that is prioritized for stability and control, and you should likely never need to swap DC’s.
I hope this helps, and thank you again for your patience as we work to catch up with all our replies!