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ceph-csi/examples/README.md
Humble Devassy Chirammal 95252dd9f6
Merge pull request from ShyamsundarR/stateless-cephfs
Make CephFS plugin stateless reusing RADOS based journal scheme
2019-06-07 10:44:18 +05:30

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# How to test RBD and CephFS plugins with Kubernetes 1.13
## Deploying Ceph-CSI services
Both `rbd` and `cephfs` directories contain `plugin-deploy.sh` and
`plugin-teardown.sh` helper scripts. You can use those to help you
deploy/teardown RBACs, sidecar containers and the plugin in one go.
By default, they look for the YAML manifests in
`../../deploy/{rbd,cephfs}/kubernetes`.
You can override this path by running `$ ./plugin-deploy.sh /path/to/my/manifests`.
## Creating CSI configuration
The CSI plugin requires configuration information regarding the Ceph cluster(s),
that would host the dynamically or statically provisioned volumes. This
is provided by adding a per-cluster identifier (referred to as clusterID), and
the required monitor details for the same, as in the provided [sample config
map](./csi-config-map-sample.yaml).
Gather the following information from the Ceph cluster(s) of choice,
* Ceph monitor list
* Typically in the output of `ceph mon dump`
* Used to prepare a list of `monitors` in the CSI configuration file
* Ceph Cluster fsid
* If choosing to use the Ceph cluster fsid as the unique value of clusterID,
* Output of `ceph fsid`
* Alternatively, choose a `<cluster-id>` value that is distinct per Ceph
cluster in use by this kubernetes cluster
Update the [sample config map](./csi-config-map-sample.yaml) with values
from a Ceph cluster and replace `<cluster-id>` with the chosen clusterID, to
create the manifest for the config map which can be updated in the cluster
using the following command,
* `kubectl replace -f ./csi-config-map-sample.yaml`
Storage class and snapshot class, using `<cluster-id>` as the value for the
option `clusterID`, can now be created on the cluster.
## Deploying the storage class
Once the plugin is successfully deployed, you'll need to customize
`storageclass.yaml` and `secret.yaml` manifests to reflect your Ceph cluster
setup.
Please consult the documentation for info about available parameters.
After configuring the secrets, monitors, etc. you can deploy a
testing Pod mounting a RBD image / CephFS volume:
```bash
kubectl create -f secret.yaml
kubectl create -f storageclass.yaml
kubectl create -f pvc.yaml
kubectl create -f pod.yaml
```
Other helper scripts:
* `logs.sh` output of the plugin
* `exec-bash.sh` logs into the plugin's container and runs bash
### How to test RBD Snapshot feature
Before continuing, make sure you enabled the required
feature gate `VolumeSnapshotDataSource=true` in your Kubernetes cluster.
In the `examples/rbd` directory you will find two files related to snapshots:
[snapshotclass.yaml](./rbd/snapshotclass.yaml) and
[snapshot.yaml](./rbd/snapshot.yaml).
Once you created your RBD volume, you'll need to customize at least
`snapshotclass.yaml` and make sure the `clusterid` parameter matches
your Ceph cluster setup.
If you followed the documentation to create the rbdplugin, you shouldn't
have to edit any other file.
After configuring everything you needed, deploy the snapshot class:
```bash
kubectl create -f snapshotclass.yaml
```
Verify that the snapshot class was created:
```console
$ kubectl get volumesnapshotclass
NAME AGE
csi-rbdplugin-snapclass 4s
```
Create a snapshot from the existing PVC:
```bash
kubectl create -f snapshot.yaml
```
To verify if your volume snapshot has successfully been created, run the following:
```console
$ kubectl get volumesnapshot
NAME AGE
rbd-pvc-snapshot 6s
```
To check the status of the snapshot, run the following:
```bash
$ kubectl describe volumesnapshot rbd-pvc-snapshot
Name: rbd-pvc-snapshot
Namespace: default
Labels: <none>
Annotations: <none>
API Version: snapshot.storage.k8s.io/v1alpha1
Kind: VolumeSnapshot
Metadata:
Creation Timestamp: 2019-02-06T08:52:34Z
Finalizers:
snapshot.storage.kubernetes.io/volumesnapshot-protection
Generation: 5
Resource Version: 84239
Self Link: /apis/snapshot.storage.k8s.io/v1alpha1/namespaces/default/volumesnapshots/rbd-pvc-snapshot
UID: 8b9b5740-29ec-11e9-8e0f-b8ca3aad030b
Spec:
Snapshot Class Name: csi-rbdplugin-snapclass
Snapshot Content Name: snapcontent-8b9b5740-29ec-11e9-8e0f-b8ca3aad030b
Source:
API Group: <nil>
Kind: PersistentVolumeClaim
Name: rbd-pvc
Status:
Creation Time: 2019-02-06T08:52:34Z
Ready To Use: true
Restore Size: 1Gi
Events: <none>
```
To be sure everything is OK you can run `rbd snap ls [your-pvc-name]` inside
one of your Ceph pod.
To restore the snapshot to a new PVC, deploy
[pvc-restore.yaml](./rbd/pvc-restore.yaml) and a testing pod
[pod-restore.yaml](./rbd/pod-restore.yaml):
```bash
kubectl create -f pvc-restore.yaml
kubectl create -f pod-restore.yaml
```
### How to test RBD MULTI_NODE_MULTI_WRITER BLOCK feature
Requires feature-gates: `BlockVolume=true` `CSIBlockVolume=true`
*NOTE* The MULTI_NODE_MULTI_WRITER capability is only available for
Volumes that are of access_type `block`
*WARNING* This feature is strictly for workloads that know how to deal
with concurrent access to the Volume (eg Active/Passive applications).
Using RWX modes on non clustered file systems with applications trying
to simultaneously access the Volume will likely result in data corruption!
Following are examples for issuing a request for a `Block`
`ReadWriteMany` Claim, and using the resultant Claim for a POD
```yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: block-pvc
spec:
accessModes:
- ReadWriteMany
volumeMode: Block
resources:
requests:
storage: 1Gi
storageClassName: csi-rbd-sc
```
Create a POD that uses this PVC:
```yaml
apiVersion: v1
kind: Pod
metadata:
name: my-pod
spec:
containers:
- name: my-container
image: debian
command: ["/bin/bash", "-c"]
args: [ "tail -f /dev/null" ]
volumeDevices:
- devicePath: /dev/rbdblock
name: my-volume
imagePullPolicy: IfNotPresent
volumes:
- name: my-volume
persistentVolumeClaim:
claimName: block-pvc
```
Now, we can create a second POD (ensure the POD is scheduled on a different
node; multiwriter single node works without this feature) that also uses this
PVC at the same time, again wait for the pod to enter running state, and verify
the block device is available.
```yaml
apiVersion: v1
kind: Pod
metadata:
name: another-pod
spec:
containers:
- name: my-container
image: debian
command: ["/bin/bash", "-c"]
args: [ "tail -f /dev/null" ]
volumeDevices:
- devicePath: /dev/rbdblock
name: my-volume
imagePullPolicy: IfNotPresent
volumes:
- name: my-volume
persistentVolumeClaim:
claimName: block-pvc
```
Wait for the PODs to enter Running state, check that our block device
is available in the container at `/dev/rdbblock` in both containers:
```bash
$ kubectl exec -it my-pod -- fdisk -l /dev/rbdblock
Disk /dev/rbdblock: 1 GiB, 1073741824 bytes, 2097152 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 4194304 bytes / 4194304 bytes
```
```bash
$ kubectl exec -it another-pod -- fdisk -l /dev/rbdblock
Disk /dev/rbdblock: 1 GiB, 1073741824 bytes, 2097152 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 4194304 bytes / 4194304 bytes
```