ceph-csi/docs/deploy-rbd.md

# CSI RBD Plugin

The RBD CSI plugin is able to provision new RBD images and
attach and mount those to workloads.

## Building

CSI RBD plugin can be compiled in a form of a binary file or in a form of a
Docker image. When compiled as a binary file, the result is stored in
`_output/` directory with the name `rbdplugin`. When compiled as an image, it's
stored in the local Docker image store.

Building binary:

```bash
make rbdplugin
```

Building Docker image:

```bash
make image-rbdplugin
```

## Configuration

**Available command line arguments:**

Option | Default value | Description
------ | ------------- | -----------
`--endpoint` | `unix://tmp/csi.sock` | CSI endpoint, must be a UNIX socket
`--drivername` | `csi-cephfsplugin` | name of the driver (Kubernetes: `provisioner` field in StorageClass must correspond to this value)
`--nodeid` | _empty_ | This node's ID
`--containerized` | true | Whether running in containerized mode
`--metadatastorage` | _empty_ | Whether should metadata be kept on node as file or in a k8s configmap (`node` or `k8s_configmap`)

**Available environmental variables:**

`HOST_ROOTFS`: rbdplugin searches `/proc` directory under the directory set by `HOST_ROOTFS`.

`KUBERNETES_CONFIG_PATH`: if you use `k8s_configmap` as metadata store, specify
the path of your k8s config file (if not specified, the plugin will assume
you're running it inside a k8s cluster and find the config itself).

`POD_NAMESPACE`: if you use `k8s_configmap` as metadata store,
`POD_NAMESPACE` is used to define in which namespace you want
the configmaps to be stored

**Available volume parameters:**

Parameter | Required | Description
--------- | -------- | -----------
`monitors` | one of `monitors` and `monValueFromSecret` must be set | Comma separated list of Ceph monitors (e.g. `192.168.100.1:6789,192.168.100.2:6789,192.168.100.3:6789`)
`monValueFromSecret` | one of `monitors` and `monValueFromSecret` must be set | a string pointing the key in the credential secret, whose value is the mon. This is used for the case when the monitors' IP or hostnames are changed, the secret can be updated to pick up the new monitors.
`pool` | yes | Ceph pool into which the RBD image shall be created
`imageFormat` | no | RBD image format. Defaults to `2`. See [man pages](http://docs.ceph.com/docs/mimic/man/8/rbd/#cmdoption-rbd-image-format)
`imageFeatures` | no | RBD image features. Available for `imageFormat=2`. CSI RBD currently supports only `layering` feature. See [man pages](http://docs.ceph.com/docs/mimic/man/8/rbd/#cmdoption-rbd-image-feature)
`csi.storage.k8s.io/provisioner-secret-name`, `csi.storage.k8s.io/node-publish-secret-name` | for Kubernetes | name of the Kubernetes Secret object containing Ceph client credentials. Both parameters should have the same value
`csi.storage.k8s.io/provisioner-secret-namespace`, `csi.storage.k8s.io/node-publish-secret-namespace` | for Kubernetes | namespaces of the above Secret objects
`mounter`| no | if set to `rbd-nbd`, use `rbd-nbd` on nodes that have `rbd-nbd` and `nbd` kernel modules to map rbd images
`fsType` | no | allows setting to `ext3 | ext-4 | xfs`, default is `ext-4`
`multiNodeWritable` | no | if set to `enabled` allows RBD volumes with MultiNode Access Modes to bypass watcher checks.  By default multiple attachments of an RBD volume are NOT allowed. Even if this option is set in the StorageClass, it's ignored if a standard SingleNodeWriter Access Mode is requested

**Warning for multiNodeWritable:**

*NOTE* the `multiNodeWritable` setting is NOT safe for use by workloads
that are not designed to coordinate access.  This does NOT add any sort
of a clustered filesystem or write syncronization, it's specifically for
special workloads that handle access coordination on their own
(ie Active/Passive scenarios).

Using this mode for general purposes *WILL RESULT IN DATA CORRUPTION*.
We attempt to limit exposure to trouble here but ignoring the Storage Class
setting unless your Volume explicitly asks for multi node access, and assume
you know what you're doing.

**Required secrets:**

Admin credentials are required for provisioning new RBD images `ADMIN_NAME`:
`ADMIN_PASSWORD` - note that the key of the key-value pair is the name of the
client with admin privileges, and the value is its password

## Deployment with Kubernetes

Requires Kubernetes 1.11

Your Kubernetes cluster must allow privileged pods (i.e. `--allow-privileged`
flag must be set to true for both the API server and the kubelet). Moreover, as
stated in the [mount propagation
docs](https://kubernetes.io/docs/concepts/storage/volumes/#mount-propagation),
the Docker daemon of the cluster nodes must allow shared mounts.

YAML manifests are located in `deploy/rbd/kubernetes`.

**Deploy RBACs for sidecar containers and node plugins:**

```bash
kubectl create -f csi-attacher-rbac.yaml
kubectl create -f csi-provisioner-rbac.yaml
kubectl create -f csi-nodeplugin-rbac.yaml
```

Those manifests deploy service accounts, cluster roles and cluster role
bindings. These are shared for both RBD and CephFS CSI plugins, as they require
the same permissions.

**Deploy CSI sidecar containers:**

```bash
kubectl create -f csi-rbdplugin-attacher.yaml
kubectl create -f csi-rbdplugin-provisioner.yaml
```

Deploys stateful sets for external-attacher and external-provisioner
sidecar containers for CSI RBD.

**Deploy RBD CSI driver:**

```bash
kubectl create -f csi-rbdplugin.yaml
```

Deploys a daemon set with two containers: CSI driver-registrar and the CSI RBD driver.

## Verifying the deployment in Kubernetes

After successfully completing the steps above, you should see output similar to this:

```bash
$ kubectl get all
NAME                              READY     STATUS    RESTARTS   AGE
pod/csi-rbdplugin-attacher-0      1/1       Running   0          23s
pod/csi-rbdplugin-fptqr           2/2       Running   0          21s
pod/csi-rbdplugin-provisioner-0   1/1       Running   0          22s

NAME                                TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)     AGE
service/csi-rbdplugin-attacher      ClusterIP   10.109.15.54   <none>        12345/TCP   26s
service/csi-rbdplugin-provisioner   ClusterIP   10.104.2.130   <none>        12345/TCP   23s

...
```

You can try deploying a demo pod from `examples/rbd` to test the deployment further.

## Deployment with Helm

The same requirements from the Kubernetes section apply here, i.e. Kubernetes
version, privileged flag and shared mounts.

The Helm chart is located in `deploy/rbd/helm`.

**Deploy Helm Chart:**

```bash
helm install ./deploy/rbd/helm
```

The Helm chart deploys all of the required resources to use the CSI RBD driver.
After deploying the chart you can verify the deployment using the instructions
above for verifying the deployment with Kubernetes