Workers#

A Strata deployment runs the same strata binary in two modes: the gateway handles S3 traffic, and one or more workers handle the background work that does not belong on the request path. Workers run inside the same binary you already deploy — set STRATA_WORKERS=gc,lifecycle,… on a gateway replica and it spawns those loops alongside the HTTP listener.

Every worker is leader-elected: across N gateway replicas, one replica acquires the lease for a given worker and runs it; the others stand by and take over if the leader’s lease expires. Leases are scoped per-worker, so different replicas can lead different workers — gc on replica A, lifecycle on replica B. Workers panic-restart on exponential backoff so a single iteration error never takes a worker offline permanently.

The workers Strata ships with:

Garbage collection — gc#

Walks the chunk-deletion queue and removes chunks that are no longer referenced by any object manifest. Sources of work include DeleteObject, lifecycle expirations, multipart aborts, and CAS losers from concurrent overwrites. Scaled across multiple replicas via STRATA_GC_SHARDS.

Lifecycle — lifecycle#

Applies bucket lifecycle policies. Transitions move objects between storage classes (STANDARD → INTELLIGENT_TIERING, for example); expirations delete objects; multipart-abort rules clean up stale multipart uploads. Per-bucket lease prevents two replicas from working the same bucket concurrently.

Rebalance — rebalance#

Migrates chunks off draining clusters. Walks every bucket whose placement policy references the draining cluster, plans per-chunk moves, and streams the bytes to the destination cluster honoring each bucket’s policy and per-cluster weights. Rate-limited by STRATA_REBALANCE_RATE_MB_S.

Replicator — replicator#

Drains the bucket-replication queue. Replication is configured per bucket via PutBucketReplication; the worker streams writes to a peer Strata endpoint over HTTP PUT, applying filter and storage class transforms.

Notification — notify#

Drains the event-notification queue. Bucket notifications configured via PutBucketNotification fan out to webhook or SQS sinks listed in STRATA_NOTIFY_TARGETS. Failed deliveries route to a dead-letter queue for inspection.

Access log — access-log#

Drains the per-bucket access-log buffer. When a bucket has logging enabled via PutBucketLogging, every request gets buffered; this worker periodically writes one AWS-format log object per flush into the target bucket.

Inventory — inventory#

Walks each bucket on its scheduled cadence and writes an inventory manifest (manifest.json + gzipped CSV) into the configured target bucket. Inventory configurations are managed via PutBucketInventoryConfiguration.

Audit export — audit-export#

Exports audit log rows older than STRATA_AUDIT_EXPORT_AFTER into gzipped JSON-lines objects in the configured export bucket, then deletes the source rows. Keeps the audit log table from growing without bound while preserving the history for compliance.

Manifest rewriter — manifest-rewriter#

One-shot-style worker that walks every object and rewrites its manifest blob into the latest encoding format. Idempotent — re-runs skip already-converted rows. Run this after upgrading to a Strata version that changes the on-disk manifest encoding.

Usage rollup — usage-rollup#

Nightly job that samples per-bucket usage counters and writes one aggregate row per (bucket, storage class, day) into the usage table. The output feeds external billing systems.

Choosing what to run#

You can run workers on dedicated replicas (gateway-only replicas plus worker-only replicas) or on every replica with the supervisor handling leader election across them. For most deployments, set STRATA_WORKERS=gc,lifecycle,notify,access-log,inventory,audit-export,usage-rollup on every gateway replica and let leader election sort out the assignments. Run rebalance only on replicas in the region where you want the migration bandwidth to originate. See Architecture: worker leader election for the implementation model and Monitoring for the metrics each worker exports.