Object Storage Overview
Object storage exposes an S3 API to the storage cluster for applications to put and get data.
This guide assumes a Rook cluster as explained in the Quickstart.
Configure an Object Store¶
Rook has the ability to either deploy an object store in Kubernetes or to connect to an external RGW service. Most commonly, the object store will be configured locally by Rook. Alternatively, if you have an existing Ceph cluster with Rados Gateways, see the external section to consume it from Rook.
Create a Local Object Store¶
The below sample will create a
CephObjectStore that starts the RGW service in the cluster with an S3 API.
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
See the Object Store CRD, for more detail on the settings available for a
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 an object store:
To confirm the object store is configured, wait for the RGW pod(s) to start:
Connect to an External Object Store¶
Rook can connect to existing RGW gateways to work in conjunction with the external mode of the
CephCluster CRD. First, create a
rgw-admin-ops-user user in the Ceph cluster with the necessary caps:
rgw-admin-ops-user user is required by the Rook operator to manage buckets and users via the admin ops and s3 api. The multisite configuration needs to be specified only if the admin sets up multisite for RGW.
Then create a secret with the user credentials:
If you have an external
CephCluster CR, you can instruct Rook to consume external gateways with the following:
Use the existing
object-external.yaml file. Even though multiple endpoints can be specified, it is recommend to use only one endpoint. This endpoint is randomly added to
configmap of OBC and secret of the
cephobjectstoreuser. Rook never guarantees the randomly picked endpoint is a working one or not. If there are multiple endpoints, please add load balancer in front of them and use the load balancer endpoint in the
When ready, the message in the
cephobjectstore status similar to this one:
Any pod from your cluster can now access this endpoint:
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).
If you’ve deployed the Rook operator in a namespace other than
rook-ceph, change the prefix in the provisioner to match the namespace you used. For example, if the Rook operator is running in the namespace
my-namespace the provisioner value should be
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 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):
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
The following commands extract key pieces of information from the secret and configmap:"
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
Host: The DNS host name where the rgw service is found in the cluster. Assuming you are using the default
rook-cephcluster, it will be
Port: The endpoint where the rgw service is listening. Run
kubectl -n rook-ceph get svc rook-ceph-rgw-my-store, to get the port.
Access key: The user's
access_keyas printed above
Secret key: The user's
secret_keyas printed above
The variables for the user generated in this example might be:
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
To test the
CephObjectStore, set the object store credentials in the toolbox pod for the
PUT or GET an object¶
Upload a file to the newly created bucket
Download and verify the file from the bucket
Rook configures health probes on the deployment created for CephObjectStore gateways. Refer to the CRD document for information about configuring the probes and monitoring the deployment status.
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
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.
Save the external service as
Now create the external service.
See both rgw services running and notice what port the external service is running on:
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 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
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:
Multisite is a feature of Ceph that allows object stores to replicate its data over multiple Ceph clusters.
Multisite also allows object stores to be independent and isolated from other object stores in a cluster.
For more information on multisite please read the ceph multisite overview for how to run it.