Container Object Storage Interface (COSI)
A Kubernetes API standard for provisioning and managing object storage buckets as native Kubernetes resources, analogous to CSI (Container Storage Interface) for block and file storage.
Summary
A Kubernetes API standard for provisioning and managing object storage buckets as native Kubernetes resources, analogous to CSI (Container Storage Interface) for block and file storage.
COSI standardizes how Kubernetes workloads request and consume object storage. Instead of manually creating S3 buckets and distributing credentials, teams define BucketClaim resources and COSI drivers provision buckets from any S3-compatible backend.
- COSI is not yet GA in Kubernetes. It is an evolving standard under kubernetes-sigs. Production adoption requires evaluating driver maturity for your specific storage backend.
- COSI provisions buckets and access credentials — it does not manage data inside buckets. Data lifecycle, retention, and organization remain application concerns.
scoped_toKubernetes Object Provisioning & Policy — the K8s-native bucket provisioning standardenablesS3 API interoperability — standardized bucket provisioning across S3-compatible backendssolvesPolicy Sprawl — declarative, RBAC-controlled bucket provisioning
Definition
A Kubernetes-native API specification for provisioning and managing object storage buckets and access credentials as declarative Kubernetes resources (BucketClaim, BucketAccess, BucketClass).
Kubernetes has standards for block (CSI) and file storage but lacks one for object storage. COSI fills this gap, enabling Kubernetes workloads to request S3-compatible buckets through the same declarative model used for all other resources.
Kubernetes-native bucket provisioning, declarative S3 access management, GitOps-driven object storage lifecycle.
Connections 4
Outbound 4
Resources 3
COSI project homepage documenting the Kubernetes-native standard for provisioning and consuming object storage buckets.
COSI specification repository defining the gRPC protocol between Kubernetes and object storage providers.
COSI API implementation repository with Kubernetes custom resource definitions for BucketClaim, BucketAccess, and BucketClass.