---
title: Container Object Storage Interface (COSI)
---

The Ceph COSI driver provisions buckets for object storage. This document instructs on enabling the driver and consuming a bucket from a sample application.

!!! note
    The Ceph COSI driver is currently in experimental mode.

## Prerequisites

COSI requires:
1. A running Rook [object store](object-storage.md)
2. [COSI controller](https://github.com/kubernetes-sigs/container-object-storage-interface-controller#readme)

Deploy the COSI controller with these commands:

```bash
kubectl apply -k github.com/kubernetes-sigs/container-object-storage-interface-api
kubectl apply -k github.com/kubernetes-sigs/container-object-storage-interface-controller
```

## Ceph COSI Driver

The Ceph COSI driver will be started when the CephCOSIDriver CR is created and when the first CephObjectStore is created.

```yaml
apiVersion: ceph.rook.io/v1
kind: CephCOSIDriver
metadata:
  name: ceph-cosi-driver
  namespace: rook-ceph
spec:
  deploymentStrategy: "Auto"
```

```console
cd deploy/examples/cosi
kubectl create -f cephcosidriver.yaml
```

The driver is created in the same namespace as Rook operator.

## Admin Operations

### Create a BucketClass and BucketAccessClass

The BucketClass and BucketAccessClass are CRDs defined by COSI. The BucketClass defines the bucket class for the bucket. The BucketAccessClass defines the access class for the bucket. Rook will automatically create a secret named with `rook-ceph-object-user-<store-name>-cosi` which contains credentials used by the COSI driver. This secret is referred by the BucketClass and BucketAccessClass as defined below:

```yaml
kind: BucketClass
apiVersion: objectstorage.k8s.io/v1alpha1
metadata:
  name: sample-bcc
driverName: ceph.objectstorage.k8s.io
deletionPolicy: Delete
parameters:
  objectStoreUserSecretName: rook-ceph-object-user-my-store-cosi
  objectStoreUserSecretNamespace: rook-ceph
---
kind: BucketAccessClass
apiVersion: objectstorage.k8s.io/v1alpha1
metadata:
  name: sample-bac
driverName: ceph.objectstorage.k8s.io
authenticationType: KEY
parameters:
  objectStoreUserSecretName: rook-ceph-object-user-my-store-cosi
  objectStoreUserSecretNamespace: rook-ceph
```

```console
kubectl create -f bucketclass.yaml -f bucketaccessclass.yaml
```

## User Operations

### Create a Bucket

To create a bucket, use the BucketClass to pointing the required object store and then define BucketClaim request as below:

```yaml
kind: BucketClaim
apiVersion: objectstorage.k8s.io/v1alpha1
metadata:
  name: sample-bc
  namespace: default # any namespace can be used
spec:
  bucketClassName: sample-bcc
  protocols:
    - s3
```

```console
kubectl create -f bucketclaim.yaml
```

### Bucket Access

Define access to the bucket by creating the BucketAccess resource:

```yaml
kind: BucketAccess
apiVersion: objectstorage.k8s.io/v1alpha1
metadata:
  name: sample-access
  namespace: default # any namespace can be used
spec:
  bucketAccessClassName: sample-bac
  bucketClaimName: sample-bc
  protocol: s3
  # Change to the name of the secret where access details are stored
  credentialsSecretName: sample-secret-name
```

```console
kubectl create -f bucketaccess.yaml
```

The secret will be created which contains the access details for the bucket in JSON format in the namespace of BucketAccess:

``` console
kubectl get secret sample-secret-name -o jsonpath='{.data.BucketInfo}' | base64 -d
```

```json
{
  "metadata": {
    "name": "bc-81733d1a-ac7a-4759-96f3-fbcc07c0cee9",
    "creationTimestamp": null
  },
  "spec": {
    "bucketName": "sample-bcc1fc94b04-6011-45e0-a3d8-b6a093055783",
    "authenticationType": "KEY",
    "secretS3": {
      "endpoint": "http://rook-ceph-rgw-my-store.rook-ceph.svc:80",
      "region": "us-east",
      "accessKeyID": "LI2LES8QMR9GB5SZLB02",
      "accessSecretKey": "s0WAmcn8N1eIBgNV0mjCwZWQmJiCF4B0SAzbhYCL"
    },
    "secretAzure": null,
    "protocols": [
      "s3"
    ]
  }
}
```

### Consuming the Bucket via secret

To access the bucket from an application pod, mount the secret for accessing the bucket:

```yaml
  volumes:
  - name: cosi-secrets
    secret:
      #  Set the name of the secret from the BucketAccess
      secretName: sample-secret-name
  spec:
    containers:
    - name: sample-app
      volumeMounts:
      - name: cosi-secrets
        mountPath: /data/cosi
```

The Secret will be mounted in the pod in the path: `/data/cosi/BucketInfo`. The app must parse the JSON object to load the bucket connection details.