Updating Scale

Summary

Fly introduces a new scaling model and command set intended to simplify how applications distribute instances across regions and manage global load. Instead of assigning instance counts to a fixed regional list, the system uses a pool of allowed regions plus global minimum and maximum instance counts, with Standard and Balanced models determining placement. Standard distributes instances evenly through the minimum and adds demand-driven instances without relocating them, while Balanced can move instances from other regions once the maximum is reached to match regional demand. The new flyctl regions command manages the pool, and flyctl scale show, standard, balanced, set, and vm commands configure or inspect scaling mode, counts, and VM size. Regional allocation can still fall back to a nearby region when the selected region cannot create an instance.

Takeaways

1. 1

   A region in the application pool is an eligible location, not a guarantee that an instance will run there; allocation can fall back to a nearby region when necessary.

2. 2

   Standard distributes instances evenly across pool regions up to the minimum, then adds instances where demand occurs without relocating existing instances.

3. 3

   flyctl regions replaces flyctl scale regions, with list, add, and remove subcommands; flyctl scale adds show, standard, balanced, and set controls.