Configuration

Every knob OpenBucket exposes, in one place. The standalone app reads its config from the environment; the embedded module (OpenBucketModule.forRoot) takes the same settings as typed options. Both fail fast — a missing or malformed secret refuses to boot rather than starting insecure.

Grab the essentials and go:

# The five required standalone settings:
DATA_DIR=/data
JWT_SECRET=$(openssl rand -base64 48)
ADMIN_PASSWORD_HASH=$(node scripts/hash-password.mjs 'your-admin-password')
ROOT_ACCESS_KEY_ID=AKIAEXAMPLE000000000
ROOT_SECRET_ACCESS_KEY=$(openssl rand -base64 48)

Everything else has a sensible default. The full, commented template lives in .env.example.

Generate strong secrets

JWT_SECRET, ROOT_SECRET_ACCESS_KEY, KEY_ENCRYPTION_SECRET, WEBHOOK_SECRET, and a token-mode METRICS_TOKEN are all validated as strong secrets: at least 32 characters, at least 8 distinct characters, not a single repeated character, and not a known placeholder (changeme, secret, password, …). openssl rand -base64 48 clears the bar every time.

Standalone environment variables

The standalone app validates process.env on boot and refuses to start if anything required is missing or malformed. Unknown variables are ignored.

Core (required)

Variable	Required	Default	Notes
DATA_DIR	✅	—	Directory for the SQLite metadata DB, blob payloads, and the generated sse.key. No trailing slash.
JWT_SECRET	✅	—	Strong secret (≥ 32 chars). Signs admin JWTs.
ADMIN_PASSWORD_HASH	✅	—	argon2id hash — generate with node scripts/hash-password.mjs '<password>'.
ROOT_ACCESS_KEY_ID	✅	—	16–32 uppercase alphanumerics (^[A-Z0-9]{16,32}$).
ROOT_SECRET_ACCESS_KEY	✅	—	Strong secret (≥ 32 chars). The root SigV4 credential.

Runtime & admin auth

Variable	Default	Notes
NODE_ENV	production	One of development / test / production.
PORT	9000	HTTP listen port.
MOUNT_PATH	— (root)	Route prefix everything mounts under — S3 (<MOUNT_PATH>/<bucket>/<key>), admin API (<MOUNT_PATH>/api/admin), admin console (<MOUNT_PATH>/admin), health & metrics. Empty = root. Set it to run behind a reverse proxy at a subpath (e.g. /storage). Normalized to a leading slash, no trailing slash.
LOG_LEVEL	info	trace / debug / info / warn / error / fatal.
ADMIN_USERNAME	admin	Bootstrap admin login.
JWT_ACCESS_TTL_SECONDS	900	Access-token lifetime (60–3600).
JWT_REFRESH_TTL_SECONDS	604800	Refresh-token lifetime (3600–2592000, i.e. 1 h–30 d).

Running at a subpath

MOUNT_PATH moves the whole OpenBucket surface under one prefix so it can sit behind a reverse proxy at, say, https://example.com/storage/… without a dedicated subdomain. The admin SPA's <base href> is rewritten to match, and the admin API stays guarded at <MOUNT_PATH>/api/admin/*. Point your S3 client's endpoint at https://example.com/storage (path-style). It is the standalone twin of the embedded module's OpenBucketModule.forRoot({ mountPath }). See Deployment → behind a reverse proxy.

S3 protocol

Variable	Default	Notes
OPENBUCKET_REGION	us-east-1	Region reported to clients. Match it in your SDK config.
OPENBUCKET_ENDPOINT	—	Optional DNS-safe hostname clients use to reach the store.
OPENBUCKET_SSE_KEY	generated	base64 of exactly 32 bytes for at-rest SSE-S3. Auto-generated to <DATA_DIR>/sse.key on first boot when unset.
KEY_ENCRYPTION_SECRET	root secret	Strong secret. KEK material for scoped sub-key secrets at rest. Falls back to ROOT_SECRET_ACCESS_KEY when unset — so rotating the root secret without setting this invalidates existing sub-key secrets.

Limits & quotas

Variable	Default	Notes
MAX_OBJECT_SIZE_MB	5120	Per-object size cap in MiB (5 GiB). Max 5242880.
MAX_MULTIPART_PARTS	10000	Max parts per multipart upload (also the ceiling).
MULTIPART_TTL_HOURS	24	Abandoned-multipart reaper TTL.
MAX_CONCURRENT_MULTIPART_UPLOADS	1000	Cap on in-flight multipart sessions. 0 = unlimited.
DATA_DIR_MIN_FREE_BYTES	104857600	Refuse writes below this free-space reserve (100 MiB).
STORAGE_QUOTA_BYTES	0	Aggregate stored-byte quota. 0 = disabled.
STORAGE_QUOTA_OBJECTS	0	Aggregate object-count quota. 0 = disabled.
S3_THROTTLE_LIMIT	1000	Per-IP S3 data-plane request budget per window. 0 disables.
S3_THROTTLE_TTL_MS	60000	S3 throttle window.

Image transforms

On-the-fly, cached image derivatives (?w=&h=&fit=&format=&q=) on GET.

Variable	Default	Notes
IMAGE_TRANSFORM_ENABLED	true	Master switch. false makes every GET serve the plain object.
MAX_TRANSFORM_DIMENSION	4096	Max requested output width/height in px. Ceiling 16384.
MAX_TRANSFORM_INPUT_BYTES	52428800	Refuse to transform a source larger than this (50 MiB).
IMAGE_TRANSFORM_LIMIT_INPUT_PIXELS	576000000	Decoded-canvas ceiling (decompression-bomb guard, 24000×24000).
IMAGE_TRANSFORM_CONCURRENCY	4	Max concurrent sharp operations. Max 64.
DERIVATIVE_CACHE_MAX_BYTES	5368709120	Derivative-cache size ceiling (5 GiB). 0 = unbounded.

Analytics & audit

Variable	Default	Notes
USAGE_ROLLUP_INTERVAL_MS	900000	Usage-rollup sample interval (floor 60000).
USAGE_RETENTION_DAYS	90	Prune usage samples older than this.
AUDIT_RETENTION_DAYS	90	Prune persisted audit rows older than this.
AUDIT_FLUSH_MS	2000	Audit buffer → SQLite flush interval (floor 250).
AUDIT_BUFFER_MAX	10000	Max buffered audit events before oldest is dropped (min 100).

Object-event webhooks

Setting WEBHOOK_URL enables durable, HMAC-signed delivery of object events. The URL must be https unless the host is loopback; the secret is then required.

Variable	Required	Default	Notes
WEBHOOK_URL		—	Target endpoint. Presence enables the delivery outbox.
WEBHOOK_SECRET	when URL set	—	Strong secret. HMAC-SHA256 signing key.
WEBHOOK_EVENTS		all three	Comma-separated: object.created,object.deleted,multipart.completed.
WEBHOOK_MAX_ATTEMPTS		8	Attempts before dead-letter (1–50).
WEBHOOK_TIMEOUT_MS		5000	Per-request timeout (500–60000).
WEBHOOK_POLL_MS		15000	Delivery tick interval (1000–300000).

Async replication

Mirror every object mutation to an external S3-compatible target. When OB_REPLICATION_ENABLED=true, the bucket and both credentials are required together — a partial config refuses to boot.

Variable	Required*	Default	Notes
OB_REPLICATION_ENABLED		false	Master switch. Off ⇒ zero cost, outbox stays empty.
OB_REPLICATION_ENDPOINT		—	S3-compatible endpoint (R2/B2/MinIO). Omit for real AWS S3. http:// warns at boot (plaintext).
OB_REPLICATION_REGION		us-east-1	Target region.
OB_REPLICATION_BUCKET	✅	—	Remote target bucket (must already exist).
OB_REPLICATION_ACCESS_KEY_ID	✅	—	Target credential.
OB_REPLICATION_SECRET_ACCESS_KEY	✅	—	Target credential (never logged).
OB_REPLICATION_FORCE_PATH_STYLE		true	true for MinIO/S3-compat; false for AWS.
OB_REPLICATION_MAX_ATTEMPTS		12	Dead-letter cap (1–50).
OB_REPLICATION_DRAIN_INTERVAL_MS		5000	Drain tick interval (1000–300000).
OB_REPLICATION_BATCH_KEYS		50	Distinct keys drained per tick (1–1000).
OB_REPLICATION_LARGE_OBJECT_THRESHOLD_BYTES		67108864	Stream via multipart above this (64 MiB).

* Required only when OB_REPLICATION_ENABLED=true.

Cold-object tiering

Offload cold objects to the replication target and rehydrate transparently on read. A no-op unless a replication target is also configured.

Variable	Default	Notes
OPENBUCKET_TIER_ENABLED	false	Master switch.
OPENBUCKET_TIER_INLINE_MAX_BYTES	268435456	Proxy read-through at/under this size; larger ⇒ presigned redirect (256 MiB).
OPENBUCKET_TIER_READTHROUGH_TIMEOUT_MS	30000	Latency bound on a proxied fetch before 503 SlowDown.
OPENBUCKET_TIER_MAX_CONCURRENT_REHYDRATE	8	Global concurrent-rehydration cap. 0 = unlimited.
OPENBUCKET_TIER_PRESIGN_TTL_SECONDS	300	TTL for presigned redirect URLs (30–3600).

Scheduled backups

Write a .zip snapshot on a schedule with union retention. When OB_SCHEDULED_BACKUP_ENABLED=true, exactly one of INTERVAL_MINUTES / CRON must be set.

Variable	Default	Notes
OB_SCHEDULED_BACKUP_ENABLED	false	Master switch.
OB_SCHEDULED_BACKUP_SCOPE	instance	instance = one snapshot; buckets = one per bucket.
OB_SCHEDULED_BACKUP_INTERVAL_MINUTES	—	Fixed interval (5–43200). Mutually exclusive with CRON.
OB_SCHEDULED_BACKUP_CRON	—	5-field cron. Mutually exclusive with INTERVAL_MINUTES.
OB_SCHEDULED_BACKUP_DIR	<DATA_DIR>/backups	Absolute snapshot directory.
OB_SCHEDULED_BACKUP_KEEP_LAST	7	Keep the newest N snapshots (hard floor, 1–1000).
OB_SCHEDULED_BACKUP_MAX_AGE_DAYS	30	Also keep anything younger than this (union, 1–3650).
OB_SCHEDULED_BACKUP_CHECK_INTERVAL_MS	60000	"Is a snapshot due?" wake tick (10000–3600000).
OB_SCHEDULED_BACKUP_PUSH_TO_REPLICATION	false	Also push each .zip to the replication target.

Integrity scrubbing

A background scrubber re-hashes local blobs against their stored SHA-256 to detect bit-rot. Strictly rate-limited so it never starves request traffic.

Variable	Default	Notes
OB_INTEGRITY_SCRUB_ENABLED	false	Master switch. A fresh install does zero extra I/O.
OB_INTEGRITY_SCRUB_INTERVAL_MS	60000	Tick interval (floor 1000).
OB_INTEGRITY_SCRUB_MAX_OBJECTS_PER_TICK	1000	Hard per-tick object cap (min 1).
OB_INTEGRITY_SCRUB_MAX_BYTES_PER_TICK	1073741824	Per-tick byte budget (1 GiB).

Restore caps & shutdown

Variable	Default	Notes
RESTORE_MAX_TOTAL_BYTES	107374182400	Total decompressed payload accepted from a restore archive (100 GiB).
RESTORE_MAX_ENTRY_BYTES	5368709120	Per-entry decompressed cap (5 GiB).
RESTORE_MAX_ENTRIES	1000000	Max payload entries in a restore archive.
RESTORE_MAX_MANIFEST_BYTES	4194304	Max buffered manifest.json bytes (4 MiB).
METRICS_MODE	off	Prometheus scrape gate: off / public / token.
METRICS_TOKEN	—	Strong bearer token — required when METRICS_MODE=token.
OTEL_TRACING_ENABLED	false	OpenTelemetry tracing (no-op unless @opentelemetry/api + an SDK are installed).
SHUTDOWN_DRAIN_MS	30000	In-flight drain budget on SIGTERM (1000–120000).

Module options (forRoot)

When you embed OpenBucket, pass these to OpenBucketModule.forRoot(...) instead of environment variables. Only dataDir and rootCredentials are required.

OpenBucketModule.forRoot({
  dataDir: '/var/lib/openbucket',
  rootCredentials: {
    accessKeyId: process.env.OB_ACCESS_KEY!,
    secretAccessKey: process.env.OB_SECRET_KEY!,
  },
  admin: {
    username: 'admin',
    passwordHash: process.env.OB_ADMIN_HASH!, // argon2id
    jwtSecret: process.env.OB_JWT_SECRET!,
  },
});

Top-level options

Option	Required	Default	Notes
dataDir	✅	—	SQLite DB + blob payloads + generated sse.key. Created on boot if absent.
rootCredentials	✅	—	{ accessKeyId, secretAccessKey } — the root SigV4 credential.
mountPath		/storage	Route prefix for all OpenBucket routes. Path-style only; '' mounts at the root.
region		us-east-1	Region reported to clients.
endpoint		—	DNS-safe hostname for endpoint discovery / presign defaults.
sseKey		generated	base64 of 32 bytes. Else generated + persisted to <dataDir>/sse.key.

admin — the admin surface

Omit the whole block to run a headless, S3-only store (no admin API, no JWT guard, no console). A present-but-partial block is rejected at boot.

Field	Required	Default	Notes
username	✅	—	Bootstrap admin login.
passwordHash	✅	—	argon2id hash of the admin password.
jwtSecret	✅	—	Strong secret signing admin JWTs.
serveUi		true	Serve the bundled Angular SPA at <mountPath>/admin.
jwtAccessTtl		900	Access-token TTL in seconds.
jwtRefreshTtl		604800	Refresh-token TTL in seconds (7 days).

limits

Field	Default	Notes
maxObjectSizeMb	5120000	Max single-object size in MiB.
maxMultipartParts	10000	Max parts per multipart upload.
multipartTtlHours	24	Abandoned-multipart TTL.

webhooks

Omit to disable HTTP webhook delivery (in-process @OnObject* handlers still work). Presence of url enables the transactional outbox + delivery runner.

Field	Required	Default	Notes
url	✅	—	Target endpoint. https required unless loopback.
secret	✅	—	Strong secret. HMAC-SHA256 signing key.
events		all three	Subset of object.created / object.deleted / multipart.completed.
maxAttempts		8	Attempts before dead-letter.
timeoutMs		5000	Per-request timeout.
pollMs		15000	Delivery tick interval.

replication

Omit to disable. A present-but-partial block is rejected at boot (require bucket + both credentials).

Field	Required	Default	Notes
bucket	✅	—	Remote target bucket (must already exist).
credentials	✅	—	{ accessKeyId, secretAccessKey } for the target.
endpoint		—	S3-compatible endpoint. Omit for real AWS S3.
region		us-east-1	Target region.
forcePathStyle		true	true for MinIO/S3-compat; false for AWS.
maxAttempts		12	Dead-letter cap.
drainIntervalMs		5000	Drain tick interval.
batchKeys		50	Distinct keys drained per tick.
largeObjectThresholdBytes		67108864	Stream via multipart above this (64 MiB).

backups

Omit to disable. Exactly one of cron / intervalMinutes must be set.

Field	Default	Notes
scope	instance	instance = one snapshot; buckets = one per bucket.
cron	—	5-field cron. Mutually exclusive with intervalMinutes.
intervalMinutes	—	Fixed interval (minutes). Mutually exclusive with cron.
dir	<dataDir>/backups	Absolute snapshot directory.
keepLast	7	Keep the newest N snapshots.
maxAgeDays	30	Also keep anything younger than this.
checkIntervalMs	60000	"Is a snapshot due?" wake tick.
pushToReplication	false	Also push each snapshot to the replication target.

metrics & tracing

Field	Default	Notes
metrics.mode	off	off / public / token — gates <mountPath>/metrics.
metrics.token	—	Strong bearer token — required when mode: 'token'.
tracing.enabled	false	OpenTelemetry span wrapping. No-op unless @opentelemetry/api + an SDK are present.

info

Static options in forRootAsync

mountPath, serveUi, and admin (the on/off switch) are static — passed alongside useFactory because routing is wired at module-config time. The admin secrets still come from the async factory. See the NestJS module reference.

Refuse-to-boot validation

Both entry points validate security-critical formats before serving a single request: a non-argon2id passwordHash, a too-short jwtSecret, a weak rootCredentials.secretAccessKey, a token-mode metrics endpoint behind a weak token, or an enabled-but-incomplete replication / backup block all abort startup with a precise message. Fail loud, never silently insecure.

Next steps

• OpenBucketService API — the in-process facade you inject.
• NestJS module reference — the full embedding guide.
• S3 compatibility — what the wire protocol supports.
• Admin API — the JSON admin surface these settings power.
• CLI reference — manage a running instance from a terminal.