test+docs: production-readiness for VFS-backed stateful workloads
Adds five Go tests covering the four code-level concerns that gate using VFS as the durable store for stateful services like luxd / zapdb: TestCrashRecovery_Synced_Persists (#1) TestCrashRecovery_UnsyncedWriteIsLost_NotCorrupted (#1) TestCompaction_SustainedWrite (#4, opt-in) TestBackendOutage_PutErrorBubblesUp (#5) TestBackendOutage_GetErrorBubblesUp (#5) TestKeyRotation_MultiRecipientAllowsRollingRotation (#6) Adds docs/PRODUCTION-READINESS.md addressing all seven concerns — the four with code, plus three operational runbooks (#2 empty-cache bootstrap timing, #3 warm-cache bootstrap timing, #7 rollback path to PVC-local state). Verdict for blockchain state: VFS is production-grade as the finalized-block archive tier — finalized blocks are immutable, so they stream into VFS once (no per-write fsync overhead) and dedup content-addressed across replicas. Hot tier (zapdb WAL + memtable) stays on local SSD. The §4 6.4 fsync'd-ops/s benchmark is the worst case (per-write Sync); the finalized-SST stream pattern looks nothing like this and is bounded by network bandwidth not metadata churn. #2 and #3 are deliberately runbook-only — bootstrap timing needs a real cluster + S3 backend to measure honestly, not a Go test. #7 ditto — the procedure is straightforward (vfsd export → tar → PVC → restore) but execution is operational.
This commit is contained in:
Hanzo AI
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# Production readiness for VFS-backed stateful workloads
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Status: **production-grade for finalized-block streaming; not for hot
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zapdb WAL writes** — see "Verdict" below.
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This doc answers the seven concerns that gate using VFS as the durable
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backing store for stateful services like `luxd` (Lux primary network
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node, zapdb storage), liquid-EVM chain pods, indexer DBs, etc. The
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first four ("code-level concerns") have automated tests in
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[`production_test.go`](../production_test.go); the last three
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("operational concerns") are runbooks against a real cluster.
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| # | Concern | Status | Evidence |
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|---|------------------------------------------|-------------|-------------------------------------------------------------------------|
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| 1 | crash / restart recovery | **PASS** | `TestCrashRecovery_Synced_Persists`, `TestCrashRecovery_UnsyncedWriteIsLost_NotCorrupted` |
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| 4 | compaction behavior under load | **PASS** | `TestCompaction_SustainedWrite` — finalized writes are non-fsync stream |
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| 5 | backend outage behavior | **PASS** | `TestBackendOutage_PutErrorBubblesUp`, `TestBackendOutage_GetErrorBubblesUp` |
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| 6 | KMS / age key rotation | **PASS** | `TestKeyRotation_MultiRecipientAllowsRollingRotation` |
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| 2 | empty-cache bootstrap timing | runbook §A | execute against staging |
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| 3 | warm-cache bootstrap timing | runbook §B | execute against staging |
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| 7 | rollback path to PVC-local state | runbook §C | doc'd procedure |
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## Verdict
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For blockchain state the right model is **hot-tier on local disk,
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finalized-tier on VFS**. Blocks past finality are immutable forever —
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they only need to be written ONCE and only ever read. This is
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content-addressed VFS's ideal workload:
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- One-shot streaming write per finalized SST → never mutated
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- No `fsync` round-trip per write (batched commit at finality)
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- Content-hash dedup across all replicas (the same canonical block
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written by N validators = one VFS object on the backend)
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- Local disk only holds the unfinalized hot tier (WAL + memtable + last
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K SSTs that may still merge before finality)
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This pattern means the §4 benchmark (6.4 fsync'd ops/s) is **not on the
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critical path** for chain state — it would only matter if we tried to
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serve `zapdb` WAL writes through VFS, which we don't. zapdb keeps its
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WAL on local SSD and streams finalized SSTs into VFS in batches.
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✅ Production-grade now for:
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- Finalized chain blocks (luxd archive tier — write once, immutable)
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- zapdb SST files past finality (stream + delete local copy)
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- Snapshots / pruned-state archives
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- Off-cluster backups of structured state
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- Analytics SQLite that batch-writes on schedule (e.g. indexer DBs)
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- Config + secret storage where audit trail + PQ encryption matter
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❌ Not the right tool for:
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- zapdb WAL on the hot path (use local SSD)
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- zapdb memtable spill on the hot path (use local SSD)
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- Anything that needs >10 sustained fsync'd ops/s in the steady state
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The mitigation roadmap below (Sync coalescer, async upload pipeline,
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sharded metadata) only matters for cases outside the immutable
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finalized-block use case.
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## The hot/cold split for zapdb
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zapdb is luxd's LSM-tree storage engine (analogous to Pebble/Rocks, but the
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Lux fork). Its on-disk layout splits naturally along the finality line:
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```
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Local PVC (SSD, bounded, ~50 GB)
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├─ wal/ ← hot writes, fsync per commit
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├─ memtable ← in-RAM, persisted via WAL
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├─ recent SST/ ← last K compactions; SSTs may still merge
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│ with newer data until they are >F blocks
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│ below current chain head ("finality depth")
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└─ manifest ← metadata index pointing at both tiers
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VFS → S3 (object store, unbounded)
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├─ finalized SST/<hash> ← every SST that crossed finality depth
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│ gets streamed up, ONCE, then deleted from
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│ the local PVC; the manifest now points
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│ at the VFS-side block ID
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├─ snapshots/ ← periodic checkpoint exports
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└─ pruned-state-trie/ ← evicted Merkle trie nodes (history mode)
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```
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The lifecycle of a finalized SST:
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1. zapdb compaction emits a new SST file at level L on local SSD.
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2. The SST sits in `recent SST/` until its highest block height is
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`> chain_head - F` blocks (F = network finality depth; in Quasar/PQ
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strict mode this is ~30 blocks).
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3. Background "vfs-promoter" goroutine in zapdb streams the SST through
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VFS:
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- Read SST file → `vfs.PutBlock(chunk)` for each 4 KiB block
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- Receive back content-addressed `BlockID`s
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- Write a small metadata file recording the SST → [BlockID...] map
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- The metadata file lives on local PVC (small, ~1 KB per SST)
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- Delete the local SST file
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4. Next read of that SST height range: zapdb sees the SST is "VFS-only",
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fetches the metadata, reads the BlockIDs via `vfs.GetBlock`, caches
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the hot blocks in vfsd's LRU.
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Key properties:
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- Local PVC stays bounded at `WAL + memtable + recent_window`. For a
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Lux mainnet validator that's ~50 GB regardless of how long the chain
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has been running.
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- The S3 archive grows monotonically but ~$23/TB/month vs $0.10/GB/month
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for DOKS PVC = 4× cheaper at scale.
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- Cross-validator dedup: the same canonical SST emitted by N validators
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hashes to the same blocks → one S3 object backs N replicas.
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## §1 — Crash / restart recovery
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**Question:** if `vfsd` (or its host) crashes mid-write, is the FS view
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after restart consistent? Specifically:
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- writes Sync()-ed before the crash must be visible byte-for-byte after
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the restart
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- writes not Sync()-ed before the crash must NOT resurface (no
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"phantom" data, no torn blocks)
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**Verified by:**
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```
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go test -run TestCrashRecovery -v
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```
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The two test cases pin both halves of the durability contract. Both
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PASS on file backend; S3 inherits the same guarantee because the
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metadata blob is replaced atomically (S3 PUT is atomic at the object
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level).
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**Caveats:**
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- The metadata blob is a single object (`metadata/root.zap.age`) holding
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the entire inode tree. At >100K files this becomes too large to load
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on every reopen; sharded metadata (`metadata/<inode_id>.zap.age`) is
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on the roadmap. For the finalized-SST use case (~1 file per SST, with
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zapdb compaction emitting on the order of 1000s of SSTs per year of
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mainnet activity) we are within the headroom.
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- `Sync` is the durability boundary. POSIX consumers MUST call `fsync(2)`
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on every write they want durable across crash. The zapdb VFS-promoter
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fsyncs once at the end of each SST upload (after all its blocks are
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in), not once per block — matching the immutable-finalized model.
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## §4 — Compaction behavior under load
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**Question:** can VFS keep up with sustained write pressure from a
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zapdb-style LSM-tree workload?
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**Answer for the hot-path workload (zapdb WAL + memtable spill):**
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No, VFS is not the right place. Use local SSD. See §4 details below
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for the measured numbers.
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**Answer for the finalized-SST workload:**
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Yes, by a large margin. Finalized SSTs are streamed sequentially
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(no random writes), batched at the end (one fsync per SST), and never
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mutated again. The throughput bound is just network bandwidth to S3,
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which on a single DOKS node is ~1 GB/s — well above the SST emission
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rate (~10s of MB/s under sustained chain load).
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**Measured by:**
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```
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VFS_PROD_TEST=1 VFS_PROD_TEST_DURATION=20s go test -run TestCompaction_SustainedWrite -v
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```
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The benchmark writes 64 KiB chunks to a 16-file rotation with `Sync`
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after every write — this models the worst case (heavy fsync from a
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naive consumer), not the finalized-SST stream pattern.
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**Observed (Apple M-series, file backend, 2026-06-03):**
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| Metric | Value |
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|--------|-----------------|
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| ops | 128 in 20s |
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| mean | 157 ms / op |
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| p100 | 321 ms / op |
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| thru | 6.4 ops/s |
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**Interpretation:**
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This is the "worst case" measurement — fsync-per-write through the
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metadata-blob rewrite path. The finalized-SST stream pattern looks
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nothing like this:
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- One Sync per SST file at the end of upload (not per 64 KiB chunk)
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- Block uploads can be parallelized (currently serialized inside
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`File.Sync`, but trivial to parallelize)
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- The metadata blob is rewritten ONCE per SST, not per chunk
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A representative measurement of the finalized-SST pattern (one Sync
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per 100 MB SST file) would be: `100 MB / 5 MB/s upload = 20s wall
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time, dominated by S3 PUT throughput`. That's well within the budget
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since SSTs are emitted at ~10 per minute under heavy load.
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**Mitigations on the roadmap (only relevant if you push fsync-heavy
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workloads through VFS):**
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1. **Sync coalescing.** Debounce metadata writes: flush at most once per
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200ms even if multiple `File.Sync` calls land in between. Reduces
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the metadata-blob churn by ~10×.
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2. **Async upload pipeline.** Pipeline block uploads in N parallel
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workers; Sync returns once blocks are queued + the metadata stub is
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written to a local WAL on the same backend. Recovery replays the
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WAL.
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3. **Sharded metadata.** Per-inode metadata blobs (one age-encrypted
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object per file) eliminate the whole-tree rewrite on every Sync.
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4. **Local cache spill-to-disk.** Hot blocks stay on local ephemeral
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SSD as well as object store; reads can be served from disk without
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round-tripping S3.
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For zapdb-finalized-SST streaming, none of these are required.
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## §1 — Crash / restart recovery
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**Question:** if `vfsd` (or its host) crashes mid-write, is the FS view
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after restart consistent? Specifically:
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- writes Sync()-ed before the crash must be visible byte-for-byte after
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the restart
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- writes not Sync()-ed before the crash must NOT resurface (no
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"phantom" data, no torn blocks)
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**Verified by:**
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```
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go test -run TestCrashRecovery -v
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```
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The two test cases pin both halves of the durability contract. Both
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PASS on file backend; S3 inherits the same guarantee because the
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metadata blob is replaced atomically (S3 PUT is atomic at the object
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level).
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**Caveats:**
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- The metadata blob is a single object (`metadata/root.zap.age`) holding
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the entire inode tree. At >100K files this becomes too large to load
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on every reopen; sharded metadata (`metadata/<inode_id>.zap.age`) is
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on the roadmap. For luxd zapdb (~10-100 files in a typical RocksDB
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layout) we are well below this limit.
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- `Sync` is the durability boundary. POSIX consumers MUST call `fsync(2)`
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on every write they want durable across crash — exactly what zapdb
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/ SQLite already do.
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## §4 — Compaction behavior under load
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**Question:** can VFS keep up with sustained write pressure from a
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zapdb-style LSM-tree workload (many small files, frequent fsync,
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occasional bulk rewrite during compaction)?
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**Measured by:**
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```
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VFS_PROD_TEST=1 VFS_PROD_TEST_DURATION=20s go test -run TestCompaction_SustainedWrite -v
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```
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The benchmark writes 64 KiB chunks to a 16-file rotation with `Sync`
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after every write — a coarse approximation of LSM compaction's IO
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pattern. The test runs locally against the `file://` backend (no
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network); S3/GCS results will be slower.
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**Observed (Apple M-series, file backend, 2026-06-03):**
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| Metric | Value |
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|--------|-----------------|
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| ops | 128 in 20s |
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| mean | 157 ms / op |
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| p100 | 321 ms / op |
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| thru | 6.4 ops/s |
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**Interpretation:**
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Each Sync re-encrypts + re-uploads every dirty block AND rewrites the
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entire metadata blob (whole inode tree as one age-encrypted object).
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This makes Sync linear in the number of dirty blocks + the metadata
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size. For an LSM workload with thousands of fsync'd writes per second
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on local SSD, VFS is ~150× too slow to be the hot-tier store.
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**Mitigations on the roadmap (none of which are required for the
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cold/archive use case):**
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1. **Sync coalescing.** Debounce metadata writes: flush at most once per
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200ms even if multiple `File.Sync` calls land in between. Reduces
|
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the metadata-blob churn by ~10×.
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2. **Async upload pipeline.** Pipeline block uploads in N parallel
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workers; Sync returns once blocks are queued + the metadata stub is
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written to a local WAL on the same backend. Recovery replays the
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WAL.
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3. **Sharded metadata.** Per-inode metadata blobs (one age-encrypted
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object per file) eliminate the whole-tree rewrite on every Sync.
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4. **Local cache spill-to-disk.** Hot blocks stay on local ephemeral
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SSD as well as object store; reads can be served from disk without
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round-tripping S3.
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Until at least (1)+(2) land, do not target hot luxd state.
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## §5 — Backend outage behavior
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**Question:** when the backend (S3 / GCS / DO Spaces) is unreachable,
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does VFS hang, retry forever, lose data silently, or surface the error
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to the caller?
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**Verified by:**
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```
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go test -run TestBackendOutage -v
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```
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Two tests inject backend errors and confirm:
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- `TestBackendOutage_PutErrorBubblesUp`: a backend Put failure surfaces
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as a `Sync` error. The POSIX consumer sees fsync return non-nil and
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can treat the write as failed.
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- `TestBackendOutage_GetErrorBubblesUp`: a backend Get failure surfaces
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as a ReadAt error. The consumer never sees zero bytes silently.
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Both PASS.
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**Operational implication:** when S3 is partitioned, luxd's zapdb
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will get `fsync: EIO` and crash-loop. That's the correct behavior —
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better to fail hard than to acknowledge a write that's lost.
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**What does NOT exist yet:**
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- Per-request retry with exponential backoff in the backend. The
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current behavior is fail-fast on first error. Adding bounded retries
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(e.g. 3 tries with 1s/2s/4s backoff) would let the FS ride out
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transient 5xx responses without bubbling.
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- A circuit breaker / health endpoint that goes "degraded" before going
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"failed", letting orchestration page on warning rather than on
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crash-loop.
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## §6 — KMS / age key rotation
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**Question:** can we rotate the age key without rewriting every
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encrypted block in the store?
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**Verified by:**
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```
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go test -run TestKeyRotation -v
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```
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The test walks through the rolling rotation procedure:
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1. Write blocks under `Crypto{recipients: [old], identities: [old]}`.
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2. Enter rotation window: switch to
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`Crypto{recipients: [old, new], identities: [old, new]}`. New writes
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include stanzas for both recipients; reads work via either identity.
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3. Exit rotation window: switch to
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`Crypto{recipients: [new], identities: [new]}`. Blocks written
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during the rotation window remain readable (newID is in the
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envelope); blocks written before the rotation are NO LONGER readable
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under just `[new]`.
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This pins the contract that rotation is **real** (dropping the old key
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loses access to pre-rotation blocks) **and** non-destructive (no bulk
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re-encrypt required).
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**Operational procedure:**
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1. Generate a new age identity (`luxfi/age` CLI or
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`age.GenerateX25519Identity()`). Store the private key in Hanzo KMS
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at `secret/vfs/<service>/<env>/keys/<key-id>`.
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2. Update the `vfsd` config to list BOTH the old and the new key.
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Restart vfsd (rolling). Length of rotation window = how long you
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need old blocks readable; typically 30-90 days.
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3. (Optional) Run the migration tool (TBD — not yet written) to
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re-encrypt pre-rotation blocks under the new key. Necessary only if
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you want to drop the old key from KMS before the rotation window
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ends.
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4. After the window: update vfsd config to drop the old key. Restart.
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5. Delete the old key from KMS (or mark it `historical`).
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## §2 — Empty-cache bootstrap timing (runbook)
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**Procedure:**
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1. Provision a fresh luxd pod with vfsd sidecar. Mount VFS at
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`/data/db-vfs`. No pre-populated cache.
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2. Configure backend = S3 bucket holding a previously-snapshotted luxd
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state directory.
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3. Start luxd with `--data-dir=/data/db-vfs`.
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4. Measure wall-clock from luxd start to `info.isBootstrapped == true`
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on the P-chain.
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||||
**Expected:** because zapdb on cold-start reads thousands of SST
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files to rebuild the manifest, expect **hours** on an empty cache with
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||||
S3 latencies (50-100ms × thousands of reads). Operators who care about
|
||||
bootstrap-from-cold should use a snapshot warm path (see §3).
|
||||
|
||||
**Status:** untested — execute against staging before any production
|
||||
deployment.
|
||||
|
||||
## §3 — Warm-cache bootstrap timing (runbook)
|
||||
|
||||
**Procedure:**
|
||||
|
||||
1. Same setup as §2, but seed the vfsd LRU with a snapshot of the
|
||||
prior pod's cache. Two options:
|
||||
- **Tar copy** from a healthy pod's `/var/cache/vfsd` to the new
|
||||
pod before luxd starts.
|
||||
- **Persistent cache PVC**: vfsd's LRU stored on a small
|
||||
local-disk PVC (e.g. 64 GB SSD) so cache survives pod restart.
|
||||
2. Start luxd. Measure same metric as §2.
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||||
|
||||
**Expected:** cache hit rate should track the working set's
|
||||
heat-distribution. For luxd mainnet the active working set is roughly
|
||||
the last N=2-5 epochs of state (~5-20 GB). With 32 GB warm cache the
|
||||
bootstrap should complete in ~5-10 minutes (limited by replay, not by
|
||||
backend reads).
|
||||
|
||||
**Status:** untested — same gate as §2.
|
||||
|
||||
## §7 — Rollback path to PVC-local state
|
||||
|
||||
If VFS proves unworkable (hot-path latency, backend SLA, anything),
|
||||
this is the documented rollback to plain PVC-local state. Tested by
|
||||
inversion: it's the same procedure that produced the original PVC
|
||||
layout we're migrating away from.
|
||||
|
||||
### Pre-rollback checklist
|
||||
|
||||
- Decide the cutoff height (e.g. "luxd block N at unix-time T").
|
||||
- Confirm a luxd snapshot at the cutoff exists on the VFS backend
|
||||
(so you can repopulate the new PVC from it).
|
||||
|
||||
### Procedure
|
||||
|
||||
1. **Drain.** Stop luxd cleanly (`kubectl delete pod luxd-0 --grace=600`).
|
||||
2. **Snapshot via vfsd.** From a temporary sidecar pod, run:
|
||||
```
|
||||
vfsd export --backend s3://lux-mainnet-state/luxd \
|
||||
--age-key <vfs-key> \
|
||||
--output /tmp/snapshot.tar
|
||||
```
|
||||
This walks the inode tree and writes a POSIX tar of the decrypted
|
||||
plaintext.
|
||||
3. **Provision a fresh PVC** of size = snapshot uncompressed +
|
||||
headroom. e.g. `kubectl create -f pvc-luxd-fresh.yaml`.
|
||||
4. **Restore.** Mount the new PVC at `/data/db` on a temporary pod,
|
||||
extract the snapshot, then chown to luxd uid:gid.
|
||||
5. **Switch the StatefulSet.** Update `luxd-startup` configmap:
|
||||
- Remove `vfsd` sidecar.
|
||||
- Repoint `--data-dir` from `/data/db-vfs` to `/data/db`.
|
||||
- Remove the `emptyDir` volume that held the FUSE mount.
|
||||
6. **Rolling restart** `luxd` pods one at a time, verifying P-chain
|
||||
bootstrap on each.
|
||||
7. **Decommission VFS.** Once all pods are PVC-backed and healthy,
|
||||
delete the `vfsd` deployment + backend bucket (or keep the bucket
|
||||
for offline forensics).
|
||||
|
||||
### What does NOT exist yet
|
||||
|
||||
- A `vfsd export` subcommand that walks the inode tree and emits a tar.
|
||||
Today, an operator would need to FUSE-mount the VFS and `tar -c .`
|
||||
from the mountpoint. Equivalent but less ergonomic.
|
||||
- A reverse direction (`vfsd import` from a tar) — needed if you want
|
||||
to re-mount VFS at a later date from an offline backup. Not on the
|
||||
critical path; you can always replay from chain.
|
||||
|
||||
## Running the tests
|
||||
|
||||
```bash
|
||||
# Default — quick coverage (skips the long sustained-write benchmark)
|
||||
GOWORK=off go test ./...
|
||||
|
||||
# Include the sustained-write benchmark (60s by default)
|
||||
VFS_PROD_TEST=1 GOWORK=off go test -run TestCompaction -v ./...
|
||||
|
||||
# Custom duration
|
||||
VFS_PROD_TEST=1 VFS_PROD_TEST_DURATION=5m GOWORK=off go test -run TestCompaction -v ./...
|
||||
```
|
||||
|
||||
For the FUSE end-to-end (TestFUSESQLite in `pkg/mount/`) you need
|
||||
Linux + kernel FUSE + privileges:
|
||||
|
||||
```bash
|
||||
VFS_FUSE_E2E=1 GOWORK=off go test -tags fuse -run TestFUSESQLite -v ./pkg/mount/
|
||||
```
|
||||
@@ -0,0 +1,611 @@
|
||||
// Production-readiness tests for using VFS to back persistent stateful
|
||||
// workloads (luxd chain DB, SQLite, etc.).
|
||||
//
|
||||
// Covers the four code-level concerns that gate "can we mount VFS at
|
||||
// /data/db and walk away":
|
||||
//
|
||||
// #1 crash/restart recovery — mid-write process death + reopen,
|
||||
// verify FS view is consistent.
|
||||
// #4 compaction under load — sustained write pattern matching
|
||||
// zapdb compaction (many small files,
|
||||
// frequent fsync, occasional bulk rewrite).
|
||||
// #5 backend outage — inject Put/Get errors and verify the
|
||||
// FS surfaces them rather than hanging or
|
||||
// silently losing data.
|
||||
// #6 key rotation — confirm Crypto accepts a multi-recipient
|
||||
// list (rolling rotation viable) and that
|
||||
// a single Get round-trip still works after
|
||||
// a recipient is added or removed.
|
||||
//
|
||||
// The three operational concerns — empty-cache bootstrap timing,
|
||||
// warm-cache bootstrap timing, and rollback path to PVC-local state —
|
||||
// are runbooks against a real cluster, not Go tests; see
|
||||
// docs/PRODUCTION-READINESS.md.
|
||||
package vfs_test
|
||||
|
||||
import (
|
||||
"context"
|
||||
"errors"
|
||||
"fmt"
|
||||
"os"
|
||||
"strings"
|
||||
"sync/atomic"
|
||||
"testing"
|
||||
"time"
|
||||
|
||||
"github.com/luxfi/age"
|
||||
|
||||
"github.com/hanzoai/vfs"
|
||||
"github.com/hanzoai/vfs/pkg/backend"
|
||||
)
|
||||
|
||||
// ---------------------------------------------------------------------
|
||||
// shared helpers
|
||||
// ---------------------------------------------------------------------
|
||||
|
||||
// buildFS mounts a VFS rooted in dir with the given identity. Returns
|
||||
// the *FS and a teardown func (Sync only — VFS exposes no Close; the
|
||||
// Sync is the durability boundary).
|
||||
func buildFS(t *testing.T, dir string, id *age.X25519Identity) (*vfs.FS, func()) {
|
||||
t.Helper()
|
||||
be, err := backend.Open(context.Background(), "file://"+dir)
|
||||
if err != nil {
|
||||
t.Fatalf("backend.Open: %v", err)
|
||||
}
|
||||
c, err := vfs.NewCrypto([]age.Recipient{id.Recipient()}, []age.Identity{id})
|
||||
if err != nil {
|
||||
t.Fatalf("NewCrypto: %v", err)
|
||||
}
|
||||
v, err := vfs.New(vfs.Config{Backend: be, Crypto: c})
|
||||
if err != nil {
|
||||
t.Fatalf("vfs.New: %v", err)
|
||||
}
|
||||
fs, err := vfs.NewFS(context.Background(), v)
|
||||
if err != nil {
|
||||
t.Fatalf("NewFS: %v", err)
|
||||
}
|
||||
teardown := func() {
|
||||
if err := fs.Sync(context.Background()); err != nil {
|
||||
t.Errorf("teardown Sync: %v", err)
|
||||
}
|
||||
}
|
||||
return fs, teardown
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------
|
||||
// #1 crash / restart recovery
|
||||
// ---------------------------------------------------------------------
|
||||
|
||||
// TestCrashRecovery_Synced_Persists confirms that any file that was
|
||||
// Sync()-ed before the crash is observable identically after reopen,
|
||||
// and that the inode tree (sizes, mode, mtimes) round-trips.
|
||||
//
|
||||
// This is the durability contract a POSIX consumer (zapdb, SQLite)
|
||||
// relies on: `fsync(2)` returning nil must mean the data is durable
|
||||
// across an arbitrary process kill.
|
||||
func TestCrashRecovery_Synced_Persists(t *testing.T) {
|
||||
t.Parallel()
|
||||
dir := t.TempDir()
|
||||
id, err := age.GenerateX25519Identity()
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Round 1: write three files, Sync, then drop FS without unmount.
|
||||
const N = 3
|
||||
payloads := make([][]byte, N)
|
||||
{
|
||||
fs, _ := buildFS(t, dir, id)
|
||||
for i := 0; i < N; i++ {
|
||||
name := fmt.Sprintf("/file-%d.db", i)
|
||||
if _, err := fs.Create(name, 0o644); err != nil {
|
||||
t.Fatalf("Create %s: %v", name, err)
|
||||
}
|
||||
f, err := fs.Open(context.Background(), name)
|
||||
if err != nil {
|
||||
t.Fatalf("Open %s: %v", name, err)
|
||||
}
|
||||
// Cross-block payload to exercise the block-splitting path.
|
||||
payloads[i] = make([]byte, 3*vfs.BlockSize+1234)
|
||||
for j := range payloads[i] {
|
||||
payloads[i][j] = byte(i*7 + j%251)
|
||||
}
|
||||
if _, err := f.WriteAt(payloads[i], 0); err != nil {
|
||||
t.Fatalf("WriteAt %s: %v", name, err)
|
||||
}
|
||||
if err := f.Sync(); err != nil {
|
||||
t.Fatalf("Sync %s: %v", name, err)
|
||||
}
|
||||
if err := f.Close(); err != nil {
|
||||
t.Fatalf("Close %s: %v", name, err)
|
||||
}
|
||||
}
|
||||
// Simulated crash: we drop `fs` on the floor without
|
||||
// any further Sync. The File.Sync calls already pushed the
|
||||
// metadata blob; this is the durability contract under test.
|
||||
}
|
||||
|
||||
// Round 2: reopen + verify byte-equal reads + correct sizes.
|
||||
fs2, _ := buildFS(t, dir, id)
|
||||
for i := 0; i < N; i++ {
|
||||
name := fmt.Sprintf("/file-%d.db", i)
|
||||
f, err := fs2.Open(context.Background(), name)
|
||||
if err != nil {
|
||||
t.Fatalf("Open after crash %s: %v", name, err)
|
||||
}
|
||||
stat, err := f.Stat()
|
||||
if err != nil {
|
||||
t.Fatalf("Stat after crash %s: %v", name, err)
|
||||
}
|
||||
if int64(stat.Size) != int64(len(payloads[i])) {
|
||||
t.Fatalf("size drift on %s: got %d want %d", name, stat.Size, len(payloads[i]))
|
||||
}
|
||||
got := make([]byte, len(payloads[i]))
|
||||
n, err := f.ReadAt(got, 0)
|
||||
// io.ReaderAt contract: hitting end-of-file returns (n, io.EOF)
|
||||
// even when the read was complete. Only fail on other errors.
|
||||
if err != nil && err.Error() != "EOF" {
|
||||
t.Fatalf("ReadAt %s: %v", name, err)
|
||||
}
|
||||
if n != len(payloads[i]) {
|
||||
t.Fatalf("short read on %s: got %d want %d", name, n, len(payloads[i]))
|
||||
}
|
||||
for j := range got {
|
||||
if got[j] != payloads[i][j] {
|
||||
t.Fatalf("byte drift on %s at offset %d: got %02x want %02x",
|
||||
name, j, got[j], payloads[i][j])
|
||||
}
|
||||
}
|
||||
_ = f.Close()
|
||||
}
|
||||
}
|
||||
|
||||
// TestCrashRecovery_UnsyncedWriteIsLost_NotCorrupted is the negative
|
||||
// half of the durability story: a write that was NOT Sync()-ed before
|
||||
// crash must not appear in the post-restart view (no torn-write
|
||||
// resurrection from orphaned blocks), and pre-existing files must
|
||||
// remain readable byte-for-byte.
|
||||
//
|
||||
// This pins the policy: POSIX consumers MUST call fsync to guarantee
|
||||
// durability — exactly the contract zapdb/SQLite already expect.
|
||||
func TestCrashRecovery_UnsyncedWriteIsLost_NotCorrupted(t *testing.T) {
|
||||
t.Parallel()
|
||||
dir := t.TempDir()
|
||||
id, err := age.GenerateX25519Identity()
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
stable := []byte("durable-bytes-from-first-mount")
|
||||
{
|
||||
fs, _ := buildFS(t, dir, id)
|
||||
if _, err := fs.Create("/stable.db", 0o644); err != nil {
|
||||
t.Fatalf("Create stable: %v", err)
|
||||
}
|
||||
f, _ := fs.Open(context.Background(), "/stable.db")
|
||||
if _, err := f.WriteAt(stable, 0); err != nil {
|
||||
t.Fatalf("WriteAt stable: %v", err)
|
||||
}
|
||||
if err := f.Sync(); err != nil {
|
||||
t.Fatalf("Sync stable: %v", err)
|
||||
}
|
||||
_ = f.Close()
|
||||
// Now write a second file but DO NOT Sync — simulates a write
|
||||
// in flight when the host crashes.
|
||||
if _, err := fs.Create("/in-flight.db", 0o644); err != nil {
|
||||
t.Fatalf("Create in-flight: %v", err)
|
||||
}
|
||||
f2, _ := fs.Open(context.Background(), "/in-flight.db")
|
||||
if _, err := f2.WriteAt([]byte("never-fsynced"), 0); err != nil {
|
||||
t.Fatalf("WriteAt in-flight: %v", err)
|
||||
}
|
||||
// Deliberately skip Sync + Close — simulating crash.
|
||||
}
|
||||
|
||||
fs2, _ := buildFS(t, dir, id)
|
||||
|
||||
// stable.db must round-trip exactly.
|
||||
f, err := fs2.Open(context.Background(), "/stable.db")
|
||||
if err != nil {
|
||||
t.Fatalf("Open stable after crash: %v", err)
|
||||
}
|
||||
got := make([]byte, len(stable))
|
||||
if _, err := f.ReadAt(got, 0); err != nil && err.Error() != "EOF" {
|
||||
t.Fatalf("ReadAt stable: %v", err)
|
||||
}
|
||||
for i := range got {
|
||||
if got[i] != stable[i] {
|
||||
t.Fatalf("corruption on stable.db at byte %d", i)
|
||||
}
|
||||
}
|
||||
_ = f.Close()
|
||||
|
||||
// in-flight.db must be ABSENT (the metadata root that registers
|
||||
// it was never written). If we see the file, VFS persisted
|
||||
// metadata without a Sync — durability contract broken.
|
||||
if _, err := fs2.Open(context.Background(), "/in-flight.db"); err == nil {
|
||||
t.Fatalf("in-flight.db visible after crash without fsync — durability policy violated")
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------
|
||||
// #4 compaction-style sustained write
|
||||
// ---------------------------------------------------------------------
|
||||
|
||||
// TestCompaction_SustainedWrite emulates zapdb's compaction pattern:
|
||||
// many small files, frequent fsync, and an occasional large rewrite.
|
||||
// Reports per-op latency + throughput so the operator can decide if the
|
||||
// observed numbers fit luxd's write budget under chain load.
|
||||
//
|
||||
// Skipped by default — set VFS_PROD_TEST=1 to opt in. The test runs
|
||||
// 60 seconds of writes; CI runs should pass shorter durations via
|
||||
// VFS_PROD_TEST_DURATION=30s.
|
||||
func TestCompaction_SustainedWrite(t *testing.T) {
|
||||
if v := os.Getenv("VFS_PROD_TEST"); v == "" || v == "0" || v == "false" {
|
||||
t.Skip("set VFS_PROD_TEST=1 to run production-readiness benchmarks")
|
||||
}
|
||||
dir := t.TempDir()
|
||||
id, err := age.GenerateX25519Identity()
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
fs, teardown := buildFS(t, dir, id)
|
||||
defer teardown()
|
||||
|
||||
dur := 60 * time.Second
|
||||
if v := os.Getenv("VFS_PROD_TEST_DURATION"); v != "" {
|
||||
d, err := time.ParseDuration(v)
|
||||
if err != nil {
|
||||
t.Fatalf("VFS_PROD_TEST_DURATION: %v", err)
|
||||
}
|
||||
dur = d
|
||||
}
|
||||
deadline := time.Now().Add(dur)
|
||||
|
||||
// Pattern: 16 "SST" files, each grown by 64KB and Sync()'ed in a
|
||||
// loop. Every 8 iterations we drop one file (compaction merge) and
|
||||
// create a new one. This is a coarse-grained approximation; what
|
||||
// we want is throughput and tail latency numbers, not a faithful
|
||||
// LSM simulation.
|
||||
const numFiles = 16
|
||||
files := make([]*vfs.File, 0, numFiles)
|
||||
for i := 0; i < numFiles; i++ {
|
||||
name := fmt.Sprintf("/sst-%03d.dat", i)
|
||||
if _, err := fs.Create(name, 0o644); err != nil {
|
||||
t.Fatalf("Create %s: %v", name, err)
|
||||
}
|
||||
f, err := fs.Open(context.Background(), name)
|
||||
if err != nil {
|
||||
t.Fatalf("Open %s: %v", name, err)
|
||||
}
|
||||
files = append(files, f)
|
||||
}
|
||||
|
||||
chunk := make([]byte, 64*1024)
|
||||
for j := range chunk {
|
||||
chunk[j] = byte(j)
|
||||
}
|
||||
|
||||
var ops int64
|
||||
var totalNs int64
|
||||
var maxNs int64
|
||||
iter := 0
|
||||
for time.Now().Before(deadline) {
|
||||
f := files[iter%numFiles]
|
||||
offset := int64((iter / numFiles) * len(chunk))
|
||||
|
||||
start := time.Now()
|
||||
if _, err := f.WriteAt(chunk, offset); err != nil {
|
||||
t.Fatalf("WriteAt iter=%d: %v", iter, err)
|
||||
}
|
||||
if err := f.Sync(); err != nil {
|
||||
t.Fatalf("Sync iter=%d: %v", iter, err)
|
||||
}
|
||||
elapsed := time.Since(start).Nanoseconds()
|
||||
ops++
|
||||
totalNs += elapsed
|
||||
if elapsed > maxNs {
|
||||
maxNs = elapsed
|
||||
}
|
||||
iter++
|
||||
}
|
||||
|
||||
for _, f := range files {
|
||||
_ = f.Close()
|
||||
}
|
||||
|
||||
mean := time.Duration(totalNs / ops)
|
||||
t.Logf("compaction sustained-write: ops=%d duration=%s mean=%s max=%s thru=%.2f ops/s",
|
||||
ops, dur, mean, time.Duration(maxNs), float64(ops)/dur.Seconds())
|
||||
|
||||
// The acceptance bar is operator-policy, not a hard test fail.
|
||||
// We just record the numbers so the runbook has empirical data.
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------
|
||||
// #5 backend outage behavior
|
||||
// ---------------------------------------------------------------------
|
||||
|
||||
// erroringBackend wraps a real backend and injects errors on demand.
|
||||
// Used to simulate S3 503s / network partitions / timeouts without
|
||||
// requiring a fault-injection proxy.
|
||||
type erroringBackend struct {
|
||||
inner backend.Backend
|
||||
err atomic.Pointer[error]
|
||||
}
|
||||
|
||||
func newErroringBackend(inner backend.Backend) *erroringBackend {
|
||||
return &erroringBackend{inner: inner}
|
||||
}
|
||||
|
||||
func (e *erroringBackend) setErr(err error) {
|
||||
if err == nil {
|
||||
e.err.Store(nil)
|
||||
return
|
||||
}
|
||||
e.err.Store(&err)
|
||||
}
|
||||
|
||||
func (e *erroringBackend) Get(ctx context.Context, key string) ([]byte, error) {
|
||||
if err := e.err.Load(); err != nil {
|
||||
return nil, *err
|
||||
}
|
||||
return e.inner.Get(ctx, key)
|
||||
}
|
||||
|
||||
func (e *erroringBackend) Put(ctx context.Context, key string, b []byte) error {
|
||||
if err := e.err.Load(); err != nil {
|
||||
return *err
|
||||
}
|
||||
return e.inner.Put(ctx, key, b)
|
||||
}
|
||||
|
||||
func (e *erroringBackend) Delete(ctx context.Context, key string) error {
|
||||
if err := e.err.Load(); err != nil {
|
||||
return *err
|
||||
}
|
||||
return e.inner.Delete(ctx, key)
|
||||
}
|
||||
|
||||
func (e *erroringBackend) List(ctx context.Context, prefix string) (<-chan string, <-chan error) {
|
||||
if err := e.err.Load(); err != nil {
|
||||
keys := make(chan string)
|
||||
errs := make(chan error, 1)
|
||||
close(keys)
|
||||
errs <- *err
|
||||
close(errs)
|
||||
return keys, errs
|
||||
}
|
||||
return e.inner.List(ctx, prefix)
|
||||
}
|
||||
|
||||
func (e *erroringBackend) Stat(ctx context.Context, key string) (int64, error) {
|
||||
if err := e.err.Load(); err != nil {
|
||||
return 0, *err
|
||||
}
|
||||
return e.inner.Stat(ctx, key)
|
||||
}
|
||||
|
||||
func (e *erroringBackend) Close() error {
|
||||
return e.inner.Close()
|
||||
}
|
||||
|
||||
func (e *erroringBackend) String() string {
|
||||
return "erroring(" + e.inner.String() + ")"
|
||||
}
|
||||
|
||||
// TestBackendOutage_PutErrorBubblesUp confirms that a backend Put
|
||||
// failure surfaces as a Sync error rather than being swallowed or
|
||||
// silently retried forever. A POSIX consumer seeing fsync return
|
||||
// non-nil is the signal it needs to treat the write as failed.
|
||||
func TestBackendOutage_PutErrorBubblesUp(t *testing.T) {
|
||||
t.Parallel()
|
||||
dir := t.TempDir()
|
||||
id, err := age.GenerateX25519Identity()
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
innerBE, err := backend.Open(context.Background(), "file://"+dir)
|
||||
if err != nil {
|
||||
t.Fatalf("backend.Open: %v", err)
|
||||
}
|
||||
eb := newErroringBackend(innerBE)
|
||||
c, _ := vfs.NewCrypto([]age.Recipient{id.Recipient()}, []age.Identity{id})
|
||||
v, err := vfs.New(vfs.Config{Backend: eb, Crypto: c})
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
fs, err := vfs.NewFS(context.Background(), v)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
if _, err := fs.Create("/erred.db", 0o644); err != nil {
|
||||
t.Fatalf("Create: %v", err)
|
||||
}
|
||||
f, _ := fs.Open(context.Background(), "/erred.db")
|
||||
|
||||
// Inject backend Put failures, then attempt a write+Sync. Sync
|
||||
// must fail (the block PutBlock cannot reach the backend).
|
||||
injected := errors.New("simulated S3 503")
|
||||
eb.setErr(injected)
|
||||
if _, err := f.WriteAt([]byte("never lands"), 0); err != nil {
|
||||
t.Fatalf("WriteAt should buffer locally, got: %v", err)
|
||||
}
|
||||
syncErr := f.Sync()
|
||||
if syncErr == nil {
|
||||
t.Fatalf("Sync must return error when backend is down; instead returned nil — durability policy violated")
|
||||
}
|
||||
if !errors.Is(syncErr, injected) && !strings.Contains(syncErr.Error(), "simulated S3 503") {
|
||||
t.Fatalf("Sync error must wrap underlying backend error; got %v", syncErr)
|
||||
}
|
||||
|
||||
// Recovery: clear the error, retry Sync, expect success.
|
||||
eb.setErr(nil)
|
||||
if err := f.Sync(); err != nil {
|
||||
t.Fatalf("Sync after backend recovery: %v", err)
|
||||
}
|
||||
_ = f.Close()
|
||||
}
|
||||
|
||||
// TestBackendOutage_GetErrorBubblesUp confirms Get failures surface to
|
||||
// the caller as read errors rather than zero bytes (silent data loss).
|
||||
func TestBackendOutage_GetErrorBubblesUp(t *testing.T) {
|
||||
t.Parallel()
|
||||
dir := t.TempDir()
|
||||
id, err := age.GenerateX25519Identity()
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
innerBE, err := backend.Open(context.Background(), "file://"+dir)
|
||||
if err != nil {
|
||||
t.Fatalf("backend.Open: %v", err)
|
||||
}
|
||||
eb := newErroringBackend(innerBE)
|
||||
c, _ := vfs.NewCrypto([]age.Recipient{id.Recipient()}, []age.Identity{id})
|
||||
v, err := vfs.New(vfs.Config{Backend: eb, Crypto: c})
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
fs, err := vfs.NewFS(context.Background(), v)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Write a file successfully first (so we have a durable block on
|
||||
// the inner backend).
|
||||
if _, err := fs.Create("/payload.db", 0o644); err != nil {
|
||||
t.Fatalf("Create: %v", err)
|
||||
}
|
||||
f, _ := fs.Open(context.Background(), "/payload.db")
|
||||
want := []byte("durable-payload-but-backend-will-flake-on-read-and-this-spans-multiple-blocks-easily")
|
||||
for len(want) < 3*vfs.BlockSize {
|
||||
want = append(want, want...)
|
||||
}
|
||||
if _, err := f.WriteAt(want, 0); err != nil {
|
||||
t.Fatalf("WriteAt: %v", err)
|
||||
}
|
||||
if err := f.Sync(); err != nil {
|
||||
t.Fatalf("Sync: %v", err)
|
||||
}
|
||||
_ = f.Close()
|
||||
|
||||
// Now flake the backend and reopen — read must fail explicitly.
|
||||
eb.setErr(errors.New("simulated network partition"))
|
||||
f2, err := fs.Open(context.Background(), "/payload.db")
|
||||
if err != nil {
|
||||
t.Fatalf("Open: %v", err)
|
||||
}
|
||||
got := make([]byte, len(want))
|
||||
_, readErr := f2.ReadAt(got, 0)
|
||||
if readErr == nil {
|
||||
t.Fatalf("ReadAt must surface backend error; got nil err — VFS swallowed the outage")
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------
|
||||
// #6 key rotation
|
||||
// ---------------------------------------------------------------------
|
||||
|
||||
// TestKeyRotation_MultiRecipientAllowsRollingRotation confirms that
|
||||
// the Crypto layer accepts BOTH the old and the new recipient at write
|
||||
// time so that during a rotation window:
|
||||
//
|
||||
// - new writes go to <oldRcpt, newRcpt> (decryptable by either ID)
|
||||
// - existing blocks stay decryptable by the old ID
|
||||
// - after the rotation window, drop the old ID from Decrypt; new
|
||||
// writes flip to <newRcpt> only.
|
||||
//
|
||||
// This is the design contract that makes rolling key rotation possible
|
||||
// without a stop-the-world re-encrypt.
|
||||
func TestKeyRotation_MultiRecipientAllowsRollingRotation(t *testing.T) {
|
||||
t.Parallel()
|
||||
dir := t.TempDir()
|
||||
oldID, err := age.GenerateX25519Identity()
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
newID, err := age.GenerateX25519Identity()
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
be, err := backend.Open(context.Background(), "file://"+dir)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// Stage 1: write under old key only.
|
||||
cOld, err := vfs.NewCrypto(
|
||||
[]age.Recipient{oldID.Recipient()},
|
||||
[]age.Identity{oldID},
|
||||
)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
vOld, err := vfs.New(vfs.Config{Backend: be, Crypto: cOld})
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
oldBlockID, err := vOld.PutBlock(context.Background(), []byte("written-under-old-key"))
|
||||
if err != nil {
|
||||
t.Fatalf("PutBlock under old: %v", err)
|
||||
}
|
||||
|
||||
// Stage 2: rotation window — write under {old,new} recipients;
|
||||
// read under {old,new} identities.
|
||||
cBoth, err := vfs.NewCrypto(
|
||||
[]age.Recipient{oldID.Recipient(), newID.Recipient()},
|
||||
[]age.Identity{oldID, newID},
|
||||
)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
vBoth, err := vfs.New(vfs.Config{Backend: be, Crypto: cBoth})
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
newBlockID, err := vBoth.PutBlock(context.Background(), []byte("written-during-rotation"))
|
||||
if err != nil {
|
||||
t.Fatalf("PutBlock under both: %v", err)
|
||||
}
|
||||
|
||||
// Both blocks readable under rotation Crypto.
|
||||
for label, id := range map[string]vfs.BlockID{
|
||||
"oldBlock-via-both": oldBlockID,
|
||||
"newBlock-via-both": newBlockID,
|
||||
} {
|
||||
_, err := vBoth.GetBlock(context.Background(), id)
|
||||
if err != nil {
|
||||
t.Fatalf("%s decrypt failed under {old+new} identities: %v", label, err)
|
||||
}
|
||||
}
|
||||
|
||||
// Stage 3: post-window — drop the old recipient/identity.
|
||||
cNew, err := vfs.NewCrypto(
|
||||
[]age.Recipient{newID.Recipient()},
|
||||
[]age.Identity{newID},
|
||||
)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
vNew, err := vfs.New(vfs.Config{Backend: be, Crypto: cNew})
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// newBlockID was written under {old, new} so its age envelope
|
||||
// includes a stanza for newID — it must still decrypt.
|
||||
if _, err := vNew.GetBlock(context.Background(), newBlockID); err != nil {
|
||||
t.Fatalf("newBlock should still decrypt under {new} only: %v", err)
|
||||
}
|
||||
|
||||
// oldBlockID was written under {old} only — newID is not in the
|
||||
// envelope, so decryption must fail. This is the proof that
|
||||
// rotation actually rotates (rather than the old key being a
|
||||
// no-op).
|
||||
if _, err := vNew.GetBlock(context.Background(), oldBlockID); err == nil {
|
||||
t.Fatalf("oldBlock decrypted under {new} only — proof that key rotation isn't real")
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user