@tomgeene As regards your question:
Is there any way to force a remote builder being created in a specific region? Not sure whether those are located in the closest region by default, which would be ams for me.
… in my experience: no. When I create a new app (with no builders), even if I specify a far-away region (like fly launch --region iad) the remote builder app that gets created is still in lhr (the closest region to me, hence why you get one in ams). Which got me thinking … can I move it manually to another region? Like iad. I tried fly regions set iad --app fly-builder-name-here … and … no, doesn’t work. It complains: Error App 'fly-builder-name-here' uses volumes to control regions. Add or remove volumes to change region placement. Which makes sense. Builders make and use a volume. And so that volume pins the builder to the region. Confirmed with fly volumes list --app fly-builder-name-here. Now … could that volume be moved or a new one made to then pin to a different region? Hmm. Maybe. I wonder what would happen if I made and attached a volume in iad, and deleted the one in lhr (the one the builder made) … I haven’t tried doing that, but you could have a try if you want. But hopefully someone from Fly can respond before. Since if ams gets sorted, this wouldn’t be needed. As it’s a total hack.