Object Storage

Object storage exposes an S3 API to the storage cluster for applications to put and get data.

Prerequisites

This guide assumes a Rook cluster as explained in the Quickstart.

Create an Object Store

The below sample will create a CephObjectStore that starts the RGW service in the cluster with an S3 API.

NOTE: This sample requires at least 3 bluestore OSDs, with each OSD located on a different node.

The OSDs must be located on different nodes, because the failureDomain is set to host and the erasureCoded chunk settings require at least 3 different OSDs (2 dataChunks + 1 codingChunks).

See the Object Store CRD, for more detail on the settings available for a CephObjectStore.

apiVersion: ceph.rook.io/v1
kind: CephObjectStore
metadata:
  name: my-store
  namespace: rook-ceph
spec:
  metadataPool:
    failureDomain: host
    replicated:
      size: 3
  dataPool:
    failureDomain: host
    erasureCoded:
      dataChunks: 2
      codingChunks: 1
  preservePoolsOnDelete: true
  gateway:
    type: s3
    sslCertificateRef:
    port: 80
    securePort:
    instances: 1

After the CephObjectStore is created, the Rook operator will then create all the pools and other resources necessary to start the service. This may take a minute to complete.

# Create the object store
kubectl create -f object.yaml

# To confirm the object store is configured, wait for the rgw pod to start
kubectl -n rook-ceph get pod -l app=rook-ceph-rgw

Create a Bucket

Now that the object store is configured, next we need to create a bucket where a client can read and write objects. A bucket can be created by defining a storage class, similar to the pattern used by block and file storage. First, define the storage class that will allow object clients to create a bucket. The storage class defines the object storage system, the bucket retention policy, and other properties required by the administrator. Save the following as storageclass-bucket-delete.yaml (the example is named as such due to the Delete reclaim policy).

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
   name: rook-ceph-bucket
provisioner: rook-ceph.ceph.rook.io/bucket
reclaimPolicy: Delete
parameters:
  objectStoreName: my-store
  objectStoreNamespace: rook-ceph
  region: us-east-1

kubectl create -f storageclass-bucket-delete.yaml

Based on this storage class, an object client can now request a bucket by creating an Object Bucket Claim (OBC). When the OBC is created, the Rook-Ceph bucket provisioner will create a new bucket. Notice that the OBC references the storage class that was created above. Save the following as object-bucket-claim-delete.yaml (the example is named as such due to the Delete reclaim policy):

apiVersion: objectbucket.io/v1alpha1
kind: ObjectBucketClaim
metadata:
  name: ceph-bucket
spec:
  generateBucketName: ceph-bkt
  storageClassName: rook-ceph-bucket

kubectl create -f object-bucket-claim-delete.yaml

Now that the claim is created, the operator will create the bucket as well as generate other artifacts to enable access to the bucket. A secret and ConfigMap are created with the same name as the OBC and in the same namespace. The secret contains credentials used by the application pod to access the bucket. The ConfigMap contains bucket endpoint information and is also consumed by the pod. See the Object Bucket Claim Documentation for more details on the CephObjectBucketClaims.

Client Connections

The following commands extract key pieces of information from the secret and configmap:”

#config-map, secret, OBC will part of default if no specific name space mentioned
export AWS_HOST=$(kubectl -n default get cm ceph-bucket -o yaml | grep BUCKET_HOST | awk '{print $2}')
export AWS_ACCESS_KEY_ID=$(kubectl -n default get secret ceph-bucket -o yaml | grep AWS_ACCESS_KEY_ID | awk '{print $2}' | base64 --decode)
export AWS_SECRET_ACCESS_KEY=$(kubectl -n default get secret ceph-bucket -o yaml | grep AWS_SECRET_ACCESS_KEY | awk '{print $2}' | base64 --decode)

Consume the Object Storage

Now that you have the object store configured and a bucket created, you can consume the object storage from an S3 client.

This section will guide you through testing the connection to the CephObjectStore and uploading and downloading from it. Run the following commands after you have connected to the Rook toolbox.

Connection Environment Variables

To simplify the s3 client commands, you will want to set the four environment variables for use by your client (ie. inside the toolbox). See above for retrieving the variables for a bucket created by an ObjectBucketClaim.

export AWS_HOST=<host>
export AWS_ENDPOINT=<endpoint>
export AWS_ACCESS_KEY_ID=<accessKey>
export AWS_SECRET_ACCESS_KEY=<secretKey>

• Host: The DNS host name where the rgw service is found in the cluster. Assuming you are using the default rook-ceph cluster, it will be rook-ceph-rgw-my-store.rook-ceph.
• Endpoint: The endpoint where the rgw service is listening. Run kubectl -n rook-ceph get svc rook-ceph-rgw-my-store, then combine the clusterIP and the port.
• Access key: The user’s access_key as printed above
• Secret key: The user’s secret_key as printed above

The variables for the user generated in this example might be:

export AWS_HOST=rook-ceph-rgw-my-store.rook-ceph
export AWS_ENDPOINT=10.104.35.31:80
export AWS_ACCESS_KEY_ID=XEZDB3UJ6X7HVBE7X7MA
export AWS_SECRET_ACCESS_KEY=7yGIZON7EhFORz0I40BFniML36D2rl8CQQ5kXU6l

The access key and secret key can be retrieved as described in the section above on client connections or below in the section creating a user if you are not creating the buckets with an ObjectBucketClaim.

Install s3cmd

To test the CephObjectStore we will install the s3cmd tool into the toolbox pod.

yum --assumeyes install s3cmd

PUT or GET an object

Upload a file to the newly created bucket

echo "Hello Rook" > /tmp/rookObj
s3cmd put /tmp/rookObj --no-ssl --host=${AWS_HOST} --host-bucket=  s3://rookbucket

Download and verify the file from the bucket

s3cmd get s3://rookbucket/rookObj /tmp/rookObj-download --no-ssl --host=${AWS_HOST} --host-bucket=
cat /tmp/rookObj-download

Access External to the Cluster

Rook sets up the object storage so pods will have access internal to the cluster. If your applications are running outside the cluster, you will need to setup an external service through a NodePort.

First, note the service that exposes RGW internal to the cluster. We will leave this service intact and create a new service for external access.

$ kubectl -n rook-ceph get service rook-ceph-rgw-my-store
NAME                     CLUSTER-IP   EXTERNAL-IP   PORT(S)     AGE
rook-ceph-rgw-my-store   10.3.0.177   <none>        80/TCP      2m

Save the external service as rgw-external.yaml:

apiVersion: v1
kind: Service
metadata:
  name: rook-ceph-rgw-my-store-external
  namespace: rook-ceph
  labels:
    app: rook-ceph-rgw
    rook_cluster: rook-ceph
    rook_object_store: my-store
spec:
  ports:
  - name: rgw
    port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: rook-ceph-rgw
    rook_cluster: rook-ceph
    rook_object_store: my-store
  sessionAffinity: None
  type: NodePort

Now create the external service.

kubectl create -f rgw-external.yaml

See both rgw services running and notice what port the external service is running on:

$ kubectl -n rook-ceph get service rook-ceph-rgw-my-store rook-ceph-rgw-my-store-external
NAME                              TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
rook-ceph-rgw-my-store            ClusterIP   10.104.82.228    <none>        80/TCP         4m
rook-ceph-rgw-my-store-external   NodePort    10.111.113.237   <none>        80:31536/TCP   39s

Internally the rgw service is running on port 80. The external port in this case is 31536. Now you can access the CephObjectStore from anywhere! All you need is the hostname for any machine in the cluster, the external port, and the user credentials.

Create a User

If you need to create an independent set of user credentials to access the S3 endpoint, create a CephObjectStoreUser. The user will be used to connect to the RGW service in the cluster using the S3 API. The user will be independent of any object bucket claims that you might have created in the earlier instructions in this document.

See the Object Store User CRD for more detail on the settings available for a CephObjectStoreUser.

apiVersion: ceph.rook.io/v1
kind: CephObjectStoreUser
metadata:
  name: my-user
  namespace: rook-ceph
spec:
  store: my-store
  displayName: "my display name"

When the CephObjectStoreUser is created, the Rook operator will then create the RGW user on the specified CephObjectStore and store the Access Key and Secret Key in a kubernetes secret in the same namespace as the CephObjectStoreUser.

# Create the object store user
kubectl create -f object-user.yaml

# To confirm the object store user is configured, describe the secret
kubectl -n rook-ceph describe secret rook-ceph-object-user-my-store-my-user

Name:		rook-ceph-object-user-my-store-my-user
Namespace:	rook-ceph
Labels:			app=rook-ceph-rgw
			      rook_cluster=rook-ceph
			      rook_object_store=my-store
Annotations:	<none>

Type:	kubernetes.io/rook

Data
====
AccessKey:	20 bytes
SecretKey:	40 bytes

The AccessKey and SecretKey data fields can be mounted in a pod as an environment variable. More information on consuming kubernetes secrets can be found in the K8s secret documentation

To directly retrieve the secrets:

kubectl -n rook-ceph get secret rook-ceph-object-user-my-store-my-user -o yaml | grep AccessKey | awk '{print $2}' | base64 --decode
kubectl -n rook-ceph get secret rook-ceph-object-user-my-store-my-user -o yaml | grep SecretKey | awk '{print $2}' | base64 --decode