Modal Storage Knowledge

Use this skill for Modal persistence and shared-state primitives. For compute, GPU, autoscaling, or deployment topics, use modal-compute:modal-compute-knowledge.

Quick routing

• Volumes: durable filesystem state mounted into functions/classes; call vol.commit() after writes that must persist.
• Dict: distributed key-value state for small shared metadata, caches, and coordination.
• Queue: producer/consumer task handoff and distributed job queues.
• CloudBucketMount: direct access to S3/GCS-compatible object storage through Modal mounts.
• Secrets: use named secrets for storage credentials; never hardcode keys.

Essential workflow

1. Identify whether the workload needs filesystem semantics, key-value state, queueing, or object-store access.
2. Mount the storage primitive explicitly on every function/class that needs it.
3. For Volumes, commit after writes and reload/read carefully across concurrent workers.
4. Keep credentials in Modal Secrets and scope them to the functions that require access.
5. Validate with a small read/write/delete test before scaling parallel jobs.

Detailed reference

See references/storage-volumes-cloud.md for examples, gotchas, and deeper storage guidance.