Fuzzball v4.2.1 release notes

Fuzzball v4.2.1 is a patch release that makes the AWS v4.1.0 -> v4.2.0 in-place upgrade reliable. The upgrade previously wedged in about one in ten attempts when a targeted EKS control-plane update persisted an inconsistent Pulumi snapshot; v4.2.1 removes that failure mode. It contains no other user-visible changes.

• AWS v4.1.0 -> v4.2.0 upgrades wedging on a corrupt Pulumi snapshot. The targeted EKS control-plane up step ran with Pulumi’s default parallel step execution. Parallel checkpointing could record a renamed dependency’s untargeted Same step after its dependents’ steps, saving a topologically invalid snapshot; the stack then refused subsequent operations and the upgrade had to be recovered by hand. About one AWS v4.1.0 -> v4.2.0 upgrade in ten hit this. The targeted up is now serialized (--parallel=1); its EKS operations are inherently sequential, so throughput is unaffected. Deployments already past v4.2.0 are not exposed to the bug; this fix matters for anyone still on v4.1.0 who has not yet upgraded.