Each Firecracker bottle created its run dir (holding an ~1G
rootfs.ext4) but never removed it — launch teardown only terminated
the VM. Every run leaked its rootfs, filling the CI runner's disk
(187 stale sandbox-tester dirs / 141G in one incident).
Register a run-dir rmtree callback on the ExitStack before the
vm.terminate callback so, LIFO, the VM is gone before its rootfs is
removed. ignore_errors keeps teardown resilient.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
didericis
2cd06814e6