HealthLog/docs/ops/backup-restore.md

Off-host backup & restore

HealthLog ships with an optional daily off-host backup that ships every user's JSON dump, encrypted with AES-256-GCM under a SEPARATE key (BACKUP_ENCRYPTION_KEY), to any S3-compatible bucket — Cloudflare R2, AWS S3, Backblaze B2, MinIO, etc.

The backup runs at 02:30 Europe/Berlin every day from the worker container (queue data-backup-offhost). Object key layout:

<bucket>/YYYY-MM-DD/user-<userId>.json.enc

Wire format (binary)

magic   = "HLBK"           (4 bytes, ASCII)
version = 0x01             (1 byte)
iv      = 12 random bytes  (AES-GCM nonce)
authTag = 16 bytes         (AES-GCM tag)
ciphertext = N bytes       (AES-256-GCM, key = BACKUP_ENCRYPTION_KEY)
plaintext  = JSON dump (UTF-8)

Required env vars

Var	Required	Notes
BACKUP_ENCRYPTION_KEY	yes	64 hex chars or 32-byte base64. Different from ENCRYPTION_KEY.
BACKUP_S3_ENDPOINT	yes	e.g. https://<account>.r2.cloudflarestorage.com
BACKUP_S3_BUCKET	yes
BACKUP_S3_ACCESS_KEY	yes
BACKUP_S3_SECRET_KEY	yes
BACKUP_S3_REGION	no	defaults to auto (Cloudflare R2)
BACKUP_RETENTION_DAYS	no	defaults to 30

Bucket lifecycle (recommended)

The worker prunes objects older than BACKUP_RETENTION_DAYS, but the storage provider's lifecycle rule is the canonical safety net:

Filter: "" (all objects)
Action: Expire after 30 days

For Cloudflare R2 add this from the bucket's Settings → Lifecycle.

Smoke test

After deploying, hit POST /api/admin/backup/test (admin-only). It performs a 1-byte PUT + GET round-trip and returns:

{
  "data": {
    "endpoint": "https://...r2.cloudflarestorage.com",
    "bucket": "healthlog-backups",
    "region": "auto",
    "putLatencyMs": 142,
    "getLatencyMs": 38,
    "ok": true
  },
  "error": null
}

The credentials are never returned.

Restore

Pick a key (e.g. 2026-05-08/user-clx123.json.enc) from the bucket and run the restore script with the same backup credentials and encryption key the backup was written under — a freshly generated BACKUP_ENCRYPTION_KEY cannot decrypt any existing object:

BACKUP_S3_ENDPOINT=https://...r2.cloudflarestorage.com       \
BACKUP_S3_BUCKET=healthlog-backups                           \
BACKUP_S3_ACCESS_KEY=...                                     \
BACKUP_S3_SECRET_KEY=...                                     \
BACKUP_S3_REGION=auto                                        \
BACKUP_ENCRYPTION_KEY=<the key the backup was written under> \
pnpm dlx tsx scripts/restore-backup.ts \
  2026-05-08/user-clx123.json.enc \
  /tmp/restored.json

Run this command from a source checkout with the production backup variables exported. The script imports the full application dependency graph, which the minimal production image does not expose as an operator scripting environment.

The script downloads the object, decrypts it, and writes the JSON dump to disk. Importing the JSON back into a HealthLog instance is left to the operator (use prisma db seed or a custom script).

What a backup deliberately does not carry

Every credential-shaped row is left out, and this is not an oversight to fix: API tokens, trusted devices, step-up elevations, known devices, clinician share links, and the account grants behind shared record access. Restoring data is rolling a record back to a known state. Restoring an authorization is different in kind, because a grant the owner revoked on Tuesday would come back alive out of Monday's file with nobody deciding it and neither person told.

What this means in practice depends on where you restore to.

Onto the same instance. Nothing changes. The restore replaces the account's data tables and does not touch grants, tokens or devices, so shared access carries on exactly as it was. Somebody who had read access before the restore still has it afterwards, now looking at the restored data.

Onto a fresh instance. None of it comes with the file. Nobody has access to anybody's record, every API token has to be reissued, every device re-trusted, and both people have to invite and accept again before sharing works. That is the fail-safe direction — access lost, never access resumed — and re-consenting is the right amount of ceremony for handing someone your health record a second time. Plan for it rather than discovering it.

The full per-model reasoning lives in src/lib/export/backup-plan.ts, where every excluded model carries a written verdict and a structural test refuses to let a new model land without one.

The weekly in-database backup (data-backup)

Separate from the off-host job above, and easy to confuse with it. A second pg-boss job writes one WEEKLY_AUTO row per user into data_backups.data — the same JSON document, gzipped and then encrypted under ENCRYPTION_KEY / ENCRYPTION_KEYS, staying inside the instance. It is what /api/admin/backups/<id>/restore reads.

Container memory

This is the part that bites. The job runs inside the app process, so V8's heap limit is the app's heap limit, and a container capped at 1 GB gives Node a 524 MB old-space limit by default. A long-lived record is bigger than it looks: several hundred thousand measurements serialise to a JSON document of a few hundred megabytes, and the writer used to need the object graph and that document resident at the same time. On a seeded account of 445 000 measurements under a 546 MB limit that is FATAL ERROR: Reached heap limit about thirty seconds in — and since the job shares the process, the whole instance restarted and every signed-in session on it went with it.

Two things changed, and both matter to an operator:

• The writer streams. The three tables that grow without bound — measurements, intake events, mood entries — are read a page at a time and serialised straight into gzip and the cipher, and every other section is released as soon as its JSON exists. On the same fixture doubled to 890 000 measurements, the pass completes inside a 296 MB heap limit; before the change, half that record did not fit in 546 MB.
• It stops itself, on its own size. The envelope writer counts the encrypted bytes it has produced for an account and gives up on the account whose stored copy would not fit this process — a fifth of V8's heap limit, which is 105 MB on the 524 MB limit a 1 GB container gets. That backup then fails for that one account, is counted in the run's users_failed and records_oversized meta, and the pass carries on with everybody else. A memory failure is a failed job rather than a restart for every user on the host.

If records_oversized is non-zero in job.data_backup, the answer is more memory, not a retry: raise the container's limit, or set NODE_OPTIONS=--max-old-space-size=<MB> to something under it. The limit is derived from the heap limit, so it rises with it.

The check deliberately reads bytes it produced and not the process's heap. A version that read the heap shipped in v1.38.6 and compared the whole process's live usage — garbage included — against 80 % of the limit. A Next.js server that has been up for a week sits at 400 MB of largely collectable heap, so the weekly pass aborted every account on the first chunk, including one whose whole stored copy is 1.2 MB, and reported success while doing it. If you are on v1.38.6, a data-backup run that finishes in seconds having backed up nothing is that defect and not your record.

The stored column is the remaining ceiling

data_backups.data is a single text column, so the finished artifact has to exist as one value before it can be written — that copy cannot be streamed away. It is the only thing left in the job that grows with the record: at a compressed blob of ~42 MB the pass peaks around 236 MB, and the growth from there is roughly twice the blob's size (the base64 answer, plus the driver's copy of it on the way to the wire). That is the ceiling the size check is set against — a fifth of the heap limit, so two copies plus the process's own live set still fit — and an account that reaches it fails as a job with a message naming both numbers. The fix at that point is to stop storing the artifact in one column: chunk it across rows, or keep only the off-host copy. Reading it back has the same shape, and worse: a restore parses the whole document, so the read path needs several times the blob in heap. An operator restoring a very large account should give the container more memory for the duration.

Monthly restore drill (automatic)

Since v1.16.4 a pg-boss job (data-restore-drill, cron 11 4 1 * * — 04:11 on the 1st of each month) exercises the read path end-to-end: fetch the most recent backup object from the bucket, decrypt it under the current BACKUP_ENCRYPTION_KEY, JSON-parse it, and sanity-check the payload shape. It performs no database restore — it validates the artefact, not the import path.

Outcomes:

• Success — record counts, object age, and sizes land in the wide-event meta (job.restore_drill).
• Stale chain — the newest object is older than 3 days: the nightly uploader has stalled (or the lifecycle rule is too aggressive). The drill pages via the worker error reporter (stderr + GlitchTip).
• Failure — empty bucket, fetch error, decryption failure (wrong or rotated key), malformed JSON: pages the same way. A decryption failure right after a BACKUP_ENCRYPTION_KEY change means the new key cannot read the existing objects — re-encrypt or accept that pre-rotation backups are only readable with the retired key.
• Not configured — deployments without the BACKUP_S3_* vars skip silently (wide-event warning only).

The drill needs no IAM grant beyond the uploader's existing GetObject + ListBucket.