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Bucket Claim

Rook supports the creation of new buckets and access to existing buckets via two custom resources:

  • an Object Bucket Claim (OBC) is custom resource which requests a bucket (new or existing) and is described by a Custom Resource Definition (CRD) shown below.
  • an Object Bucket (OB) is a custom resource automatically generated when a bucket is provisioned. It is a global resource, typically not visible to non-admin users, and contains information specific to the bucket. It is described by an OB CRD, also shown below.

An OBC references a storage class which is created by an administrator. The storage class defines whether the bucket requested is a new bucket or an existing bucket. It also defines the bucket retention policy. Users request a new or existing bucket by creating an OBC which is shown below. The ceph provisioner detects the OBC and creates a new bucket or grants access to an existing bucket, depending the storage class referenced in the OBC. It also generates a Secret which provides credentials to access the bucket, and a ConfigMap which contains the bucket's endpoint. Application pods consume the information in the Secret and ConfigMap to access the bucket. Please note that to make provisioner watch the cluster namespace only you need to set ROOK_OBC_WATCH_OPERATOR_NAMESPACE to true in the operator manifest, otherwise it watches all namespaces.

The OBC provisioner name found in the storage class by default includes the operator namespace as a prefix. A custom prefix can be applied by the operator setting in the rook-ceph-operator-config configmap: ROOK_OBC_PROVISIONER_NAME_PREFIX.


Changing the prefix is not supported on existing clusters. This may impact the function of existing OBCs.


OBC Custom Resource

kind: ObjectBucketClaim
  name: ceph-bucket [1]
  namespace: rook-ceph [2]
  bucketName: [3]
  generateBucketName: photo-booth [4]
  storageClassName: rook-ceph-bucket [5]
  additionalConfig: [6]
    maxObjects: "1000"
    maxSize: "2G"
  1. name of the ObjectBucketClaim. This name becomes the name of the Secret and ConfigMap.
  2. namespace(optional) of the ObjectBucketClaim, which is also the namespace of the ConfigMap and Secret.
  3. bucketName name of the bucket. Not recommended for new buckets since names must be unique within an entire object store.
  4. generateBucketName value becomes the prefix for a randomly generated name, if supplied then bucketName must be empty. If both bucketName and generateBucketName are supplied then BucketName has precedence and GenerateBucketName is ignored. If both bucketName and generateBucketName are blank or omitted then the storage class is expected to contain the name of an existing bucket. It's an error if all three bucket related names are blank or omitted.
  5. storageClassName which defines the StorageClass which contains the names of the bucket provisioner, the object-store and specifies the bucket retention policy.
  6. additionalConfig is an optional list of key-value pairs used to define attributes specific to the bucket being provisioned by this OBC. This information is typically tuned to a particular bucket provisioner and may limit application portability. Options supported:

    • maxObjects: The maximum number of objects in the bucket
    • maxSize: The maximum size of the bucket, please note minimum recommended value is 4K.

OBC Custom Resource after Bucket Provisioning

kind: ObjectBucketClaim
  creationTimestamp: "2019-10-18T09:54:01Z"
  generation: 2
  name: ceph-bucket
  namespace: default [1]
  resourceVersion: "559491"
  ObjectBucketName: obc-default-ceph-bucket [2]
  additionalConfig: null
  bucketName: photo-booth-c1178d61-1517-431f-8408-ec4c9fa50bee [3]
  storageClassName: rook-ceph-bucket [4]
  phase: Bound [5]
  1. namespace where OBC got created.
  2. ObjectBucketName generated OB name created using name space and OBC name.
  3. the generated (in this case), unique bucket name for the new bucket.
  4. name of the storage class from OBC got created.
  5. phases of bucket creation:
    • Pending: the operator is processing the request.
    • Bound: the operator finished processing the request and linked the OBC and OB
    • Released: the OB has been deleted, leaving the OBC unclaimed but unavailable.
    • Failed: not currently set.

App Pod

apiVersion: v1
kind: Pod
  name: app-pod
  namespace: dev-user
  - name: mycontainer
    image: redis
    envFrom: [1]
    - configMapRef:
        name: ceph-bucket [2]
    - secretRef:
        name: ceph-bucket [3]
  1. use env: if mapping of the defined key names to the env var names used by the app is needed.
  2. makes available to the pod as env variables: BUCKET_HOST, BUCKET_PORT, BUCKET_NAME
  3. makes available to the pod as env variables: AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY


kind: StorageClass
  name: rook-ceph-bucket
    aws-s3/object [1]
provisioner: [2]
parameters: [3]
  objectStoreName: my-store
  objectStoreNamespace: rook-ceph
  bucketName: ceph-bucket [4]
reclaimPolicy: Delete [5]
  1. label(optional) here associates this StorageClass to a specific provisioner.
  2. provisioner responsible for handling OBCs referencing this StorageClass.
  3. all parameter required.
  4. bucketName is required for access to existing buckets but is omitted when provisioning new buckets. Unlike greenfield provisioning, the brownfield bucket name appears in the StorageClass, not the OBC.
  5. rook-ceph provisioner decides how to treat the reclaimPolicy when an OBC is deleted for the bucket. See explanation as specified in Kubernetes

    • Delete = physically delete the bucket.
    • Retain = do not physically delete the bucket.