Playground: cover the leaked-fc leak on failed restore - #1131
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Two paths could leave a firecracker process alive after a query- triggered restore failed, holding fc-tap-<slot> and breaking the next /query with "Open tap device failed: … Resource busy (os error 16). Invalid TUN/TAP Backend provided by fc-tap-N": 1. vm_manager._restore_snapshot: _boot's own except handler already reaps on _configure_boot failure, but if the guest agent never answers /health (_wait_for_agent) or the daemon never reports /ready (_wait_for_daemon_ready), we fall through with vm.pid still set and no cleanup. Wrap both waits and shut down the fc process + teardown_tap on failure. 2. main._dispatch_query: even with the vm_manager fix, an out-of-band raise (e.g. an aiohttp ServerDisconnectedError before we ever entered _restore_snapshot's try) can still leak. Kick the VM before the second attempt so ensure_tap on attempt-2 always sees a clean slot.
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Two paths could leave a firecracker process alive after a query- triggered restore failed, holding fc-tap- and breaking the next /query with "Open tap device failed: … Resource busy (os error 16). Invalid TUN/TAP Backend provided by fc-tap-N":
vm_manager._restore_snapshot: _boot's own except handler already reaps on _configure_boot failure, but if the guest agent never answers /health (_wait_for_agent) or the daemon never reports /ready (_wait_for_daemon_ready), we fall through with vm.pid still set and no cleanup. Wrap both waits and shut down the fc process + teardown_tap on failure.
main._dispatch_query: even with the vm_manager fix, an out-of-band raise (e.g. an aiohttp ServerDisconnectedError before we ever entered _restore_snapshot's try) can still leak. Kick the VM before the second attempt so ensure_tap on attempt-2 always sees a clean slot.