diff --git a/bot_bottle/backend/firecracker/cleanup.py b/bot_bottle/backend/firecracker/cleanup.py index af41e29..6e9fe2d 100644 --- a/bot_bottle/backend/firecracker/cleanup.py +++ b/bot_bottle/backend/firecracker/cleanup.py @@ -1,8 +1,23 @@ """Cleanup for the Firecracker backend. -Orphans are: firecracker VMM processes whose config lives under our run -dir, and the per-bottle run dirs. TAP slots free themselves (the flock -drops when the launcher exits), so there is nothing to reclaim there. +Reaps *orphans* only — resources with no live VM behind them: + + * orphan run dirs: a per-bottle run dir (holding the ~1G rootfs.ext4) + whose firecracker process has exited. These leak when a launch is + hard-killed before its teardown runs (host OOM/crash, a cancelled CI + job, `kill -9`); the clean-exit path already removes its own dir in + launch.py. + * orphan VM pids: a firecracker process whose run dir is already gone + — a VMM left lingering after its dir was removed. + +A run dir with a *live* firecracker process is a running bottle and is +left strictly alone: it is neither killed nor removed. (The backend's +`enumerate_active` registry is still a stub — #354 — so a live process +is the only reliable "this bottle is in use" signal we have. Once the +registry lands, registry-orphaned-but-running VMs can be reaped too.) + +TAP slots free themselves (the flock drops when the launcher exits), so +there is nothing to reclaim there. """ from __future__ import annotations @@ -22,38 +37,73 @@ def _run_root() -> Path: return util.cache_dir() / "run" -def _orphan_vm_pids() -> list[int]: - """firecracker processes whose --config-file is under our run dir.""" - run_root = str(_run_root()) +def _run_dir_of(cmd: str, run_root: Path) -> Path | None: + """The bottle run dir a firecracker cmdline belongs to, or None. + + A bottle VM is launched with `--config-file //config.json`, + so the run dir is the config file's parent when it sits directly under + the run root. Anything else (a builder VM, the infra VM elsewhere) is + not ours to reap here. + """ + toks = cmd.split() + for i, tok in enumerate(toks): + if tok == "--config-file" and i + 1 < len(toks): + parent = Path(toks[i + 1]).parent + if parent.parent == run_root: + return parent + return None + + +def _scan_processes(run_root: Path) -> tuple[set[str], list[int]]: + """Inspect running firecracker VMs under ``run_root``. + + Returns ``(live_run_dirs, orphan_pids)``: + * ``live_run_dirs`` — run dirs backed by a running VM (never reaped); + * ``orphan_pids`` — firecracker pids whose run dir no longer exists + (a lingering VMM to kill). + """ result = subprocess.run( ["pgrep", "-a", "firecracker"], capture_output=True, text=True, check=False, ) if result.returncode != 0: - return [] - pids: list[int] = [] + return set(), [] + live: set[str] = set() + orphan_pids: list[int] = [] for line in result.stdout.splitlines(): parts = line.split(None, 1) - if len(parts) != 2 or run_root not in parts[1]: + if len(parts) != 2: continue try: - pids.append(int(parts[0])) + pid = int(parts[0]) except ValueError: continue - return pids + run_dir = _run_dir_of(parts[1], run_root) + if run_dir is None: + continue + if run_dir.is_dir(): + live.add(str(run_dir)) + else: + orphan_pids.append(pid) + return live, orphan_pids -def _run_dirs() -> list[str]: - run_root = _run_root() +def _orphan_run_dirs(run_root: Path, live: set[str]) -> list[str]: + """Run dirs with no live VM behind them — the leaked ones to remove.""" if not run_root.is_dir(): return [] - return sorted(str(p) for p in run_root.iterdir() if p.is_dir()) + return sorted( + str(p) for p in run_root.iterdir() + if p.is_dir() and str(p) not in live + ) def prepare_cleanup() -> FirecrackerBottleCleanupPlan: + run_root = _run_root() + live, orphan_pids = _scan_processes(run_root) return FirecrackerBottleCleanupPlan( - vm_pids=tuple(_orphan_vm_pids()), - run_dirs=tuple(_run_dirs()), + vm_pids=tuple(orphan_pids), + run_dirs=tuple(_orphan_run_dirs(run_root, live)), ) diff --git a/tests/unit/test_firecracker_cleanup.py b/tests/unit/test_firecracker_cleanup.py index 27b0097..8670783 100644 --- a/tests/unit/test_firecracker_cleanup.py +++ b/tests/unit/test_firecracker_cleanup.py @@ -10,7 +10,9 @@ classmethods forward to their module. from __future__ import annotations import subprocess +import tempfile import unittest +from pathlib import Path from unittest.mock import patch from bot_bottle.backend.firecracker import cleanup as fc_cleanup @@ -23,32 +25,69 @@ def _proc(stdout: str = "", returncode: int = 0) -> "subprocess.CompletedProcess return subprocess.CompletedProcess([], returncode, stdout=stdout, stderr="") -class TestOrphanEnumeration(unittest.TestCase): - def test_orphan_vm_pids_filters_by_run_dir(self): - run_root = str(fc_cleanup._run_root()) - out = ( - f"111 firecracker --config-file {run_root}/dev-a/config.json\n" - "222 firecracker --config-file /somewhere/else/config.json\n" - "notanint firecracker --config-file " + run_root + "/x\n" +class TestProcessScan(unittest.TestCase): + def test_run_dir_of_matches_only_direct_children(self): + run_root = Path("/cache/run") + self.assertEqual( + Path("/cache/run/dev-a"), + fc_cleanup._run_dir_of( + f"firecracker --config-file {run_root}/dev-a/config.json", run_root + ), + ) + # infra/builder VMs elsewhere, or nested paths, are not ours. + self.assertIsNone( + fc_cleanup._run_dir_of("firecracker --config-file /elsewhere/config.json", run_root) + ) + self.assertIsNone( + fc_cleanup._run_dir_of("firecracker --no-config", run_root) ) - with patch.object(fc_cleanup.subprocess, "run", return_value=_proc(out)): - self.assertEqual([111], fc_cleanup._orphan_vm_pids()) - def test_orphan_vm_pids_empty_when_pgrep_fails(self): + def test_scan_splits_live_dirs_from_orphan_pids(self): + with tempfile.TemporaryDirectory() as tmp: + run_root = Path(tmp) + (run_root / "live-a").mkdir() # dir present -> live VM, protected + # "gone-b" dir intentionally absent -> lingering VMM, orphan pid + out = ( + f"111 firecracker --config-file {run_root}/live-a/config.json\n" + f"222 firecracker --config-file {run_root}/gone-b/config.json\n" + "333 firecracker --config-file /elsewhere/config.json\n" + "notanint firecracker --config-file x\n" + ) + with patch.object(fc_cleanup.subprocess, "run", return_value=_proc(out)): + live, orphan_pids = fc_cleanup._scan_processes(run_root) + self.assertEqual({str(run_root / "live-a")}, live) + self.assertEqual([222], orphan_pids) + + def test_scan_empty_when_pgrep_fails(self): with patch.object(fc_cleanup.subprocess, "run", return_value=_proc(returncode=1)): - self.assertEqual([], fc_cleanup._orphan_vm_pids()) + self.assertEqual((set(), []), fc_cleanup._scan_processes(Path("/x"))) - def test_run_dirs_empty_when_absent(self): - with patch.object(fc_cleanup.util, "cache_dir") as cache: - cache.return_value.__truediv__.return_value.is_dir.return_value = False - self.assertEqual([], fc_cleanup._run_dirs()) + def test_orphan_run_dirs_excludes_live_and_missing_root(self): + with tempfile.TemporaryDirectory() as tmp: + run_root = Path(tmp) + (run_root / "live-a").mkdir() + (run_root / "dead-b").mkdir() + live = {str(run_root / "live-a")} + self.assertEqual( + [str(run_root / "dead-b")], + fc_cleanup._orphan_run_dirs(run_root, live), + ) + # absent run root -> nothing to reap + self.assertEqual([], fc_cleanup._orphan_run_dirs(Path("/nope/run"), set())) - def test_prepare_cleanup_assembles_plan(self): - with patch.object(fc_cleanup, "_orphan_vm_pids", return_value=[7]), \ - patch.object(fc_cleanup, "_run_dirs", return_value=["/run/x"]): - plan = fc_cleanup.prepare_cleanup() - self.assertEqual((7,), plan.vm_pids) - self.assertEqual(("/run/x",), plan.run_dirs) + def test_prepare_cleanup_reaps_orphans_only(self): + """The live VM's dir is never in the plan; the dead one is.""" + with tempfile.TemporaryDirectory() as tmp: + run_root = Path(tmp) + (run_root / "live-a").mkdir() + (run_root / "dead-b").mkdir() + out = f"111 firecracker --config-file {run_root}/live-a/config.json\n" + with patch.object(fc_cleanup, "_run_root", return_value=run_root), \ + patch.object(fc_cleanup.subprocess, "run", return_value=_proc(out)): + plan = fc_cleanup.prepare_cleanup() + self.assertEqual((), plan.vm_pids) + self.assertEqual((str(run_root / "dead-b"),), plan.run_dirs) + self.assertNotIn(str(run_root / "live-a"), plan.run_dirs) class TestCleanupRemoval(unittest.TestCase):