These instructions are about using the external Ceph driver in an RKE2 cluster. If you are using RKE, additional steps are required. For details, refer to this section.

Requirements

Make sure ceph-common and xfsprogs packages are installed on SLE worker nodes.

Using the Ceph Driver with RKE

The resources below are fully compatible with RKE based clusters, but there is a need to do an additional kubelet configuration for RKE.

On RKE clusters, the kubelet component is running in a Docker container and doesn’t have access to the host’s kernel modules as rbd and libceph by default.

To solve this limitation, you can either run modprobe rbd on worker nodes, or configure the kubelet containers to automatically mount the /lib/modules directory from the host into the container.

For the kubelet configuration, put the following lines into the cluster.yml file prior to RKE cluster provisioning. You can also modify the cluster.yml later in the Rancher UI by clicking on Edit Cluster > Edit as YAML and restarting the worker nodes.

services:
  kubelet:
    extra_binds:
      - '/lib/modules:/lib/modules:ro'

For more information about the extra_binds directive, refer to this section.

Installing the ceph-csi driver on an RKE2 cluster

Note: These steps are needed for dynamic RBD provisioning only.

For more information about the ceph-csi-rbd chart, refer to this page.

To get details about your SES cluster, run:

ceph mon dump

Read its output:

dumped monmap epoch 3
epoch 3
fsid 79179d9d-98d8-4976-ab2e-58635caa7235
last_changed 2021-02-11T10:56:42.110184+0000
created 2021-02-11T10:56:22.913321+0000
min_mon_release 15 (octopus)
0: [v2:10.85.8.118:3300/0,v1:10.85.8.118:6789/0] mon.a
1: [v2:10.85.8.123:3300/0,v1:10.85.8.123:6789/0] mon.b
2: [v2:10.85.8.124:3300/0,v1:10.85.8.124:6789/0] mon.c

Later you’ll need the fsid and mon addresses values.

Install the ceph-csi Driver Using Helm

Run these commands:

helm repo add ceph-csi https://ceph.github.io/csi-charts
helm repo update
helm search repo ceph-csi -l
helm inspect values ceph-csi/ceph-csi-rbd > ceph-csi-rbd-values.yaml

Modify the ceph-csi-rbd-values.yaml file and keep there only the required changes:

# ceph-csi-rbd-values.yaml
csiConfig:
  - clusterID: "79179d9d-98d8-4976-ab2e-58635caa7235"
    monitors:
      - "10.85.8.118:6789"
      - "10.85.8.123:6789"
      - "10.85.8.124:6789"
provisioner:
  name: provisioner
  replicaCount: 2

Make sure the ceph monitors are reachable from the RKE2 cluster, for example, by ping.

kubectl create namespace ceph-csi-rbd
helm install --namespace ceph-csi-rbd ceph-csi-rbd ceph-csi/ceph-csi-rbd --values ceph-csi-rbd-values.yaml
kubectl rollout status deployment ceph-csi-rbd-provisioner -n ceph-csi-rbd
helm status ceph-csi-rbd -n ceph-csi-rbd

in case you’d like to modify the configuration directly via Helm, you may adapt the ceph-csi-rbd-values.yaml file and call:

helm upgrade \
  --namespace ceph-csi-rbd ceph-csi-rbd ceph-csi/ceph-csi-rbd --values ceph-csi-rbd-values.yaml

Creating RBD Ceph Resources

# Create a ceph pool:
ceph osd pool create myPool 64 64

# Create a block device pool:
rbd pool init myPool

# Create a block device image:
rbd create -s 2G myPool/image

# Create a block device user and record the key:
ceph auth get-or-create-key client.myPoolUser mon "allow r" osd "allow class-read object_prefix rbd_children, allow rwx pool=myPool" | tr -d '\n' | base64
QVFDZ0R5VmdyRk9KREJBQTJ5b2s5R1E2NUdSWExRQndhVVBwWXc9PQ==

# Encode the ceph user myPoolUser into a bash64 hash:
echo "myPoolUser" | tr -d '\n' | base64
bXlQb29sVXNlcg==

# Create a block device admin user and record the key:
ceph auth get-or-create-key client.myPoolAdmin mds 'allow *' mgr 'allow *' mon 'allow *' osd 'allow * pool=myPool' | tr -d '\n' | base64
QVFCK0hDVmdXSjQ1T0JBQXBrc0VtcVhlZFpjc0JwaStIcmU5M3c9PQ==

# Encode the ceph user myPoolAdmin into a bash64 hash:
echo "myPoolAdmin" | tr -d '\n' | base64
bXlQb29sQWRtaW4=

Configure RBD Ceph Access Secrets

User Account

For static RBD provisioning (the image within the ceph pool must exist), run these commands:

cat > ceph-user-secret.yaml << EOF
apiVersion: v1
kind: Secret
metadata:
  name: ceph-user
  namespace: default
type: kubernetes.io/rbd
data:
  userID: bXlQb29sVXNlcg==
  userKey: QVFDZ0R5VmdyRk9KREJBQTJ5b2s5R1E2NUdSWExRQndhVVBwWXc9PQ==
EOF

kubectl apply -f ceph-user-secret.yaml

Admin Account

For dynamic RBD provisioning (used for automatic image creation within a given ceph pool), run these commands:

cat > ceph-admin-secret.yaml << EOF
apiVersion: v1
kind: Secret
metadata:
  name: ceph-admin
  namespace: default
type: kubernetes.io/rbd
data:
  userID: bXlQb29sQWRtaW4=
  userKey: QVFCK0hDVmdXSjQ1T0JBQXBrc0VtcVhlZFpjc0JwaStIcmU5M3c9PQ==
EOF

kubectl apply -f ceph-admin-secret.yaml

Create RBD Testing Resources

Using RBD in Pods

# pod
cat > ceph-rbd-pod-inline.yaml << EOF
apiVersion: v1
kind: Pod
metadata:
  name: ceph-rbd-pod-inline
spec:
  containers:
  - name: ceph-rbd-pod-inline
    image: busybox
    command: ["sleep", "infinity"]
    volumeMounts:
    - mountPath: /mnt/ceph_rbd
      name: volume
  volumes:
  - name: volume
    rbd:
      monitors:
      - 10.85.8.118:6789
      - 10.85.8.123:6789
      - 10.85.8.124:6789
      pool: myPool
      image: image
      user: myPoolUser
      secretRef:
        name: ceph-user
      fsType: ext4
      readOnly: false
EOF
 
kubectl apply -f ceph-rbd-pod-inline.yaml
kubectl get pod
kubectl exec pod/ceph-rbd-pod-inline -- df -k | grep rbd

Using RBD in Persistent Volumes

# pod-pvc-pv
cat > ceph-rbd-pod-pvc-pv-allinone.yaml << EOF
apiVersion: v1
kind: PersistentVolume
metadata:
  name: ceph-rbd-pv
spec:
  capacity:
    storage: 2Gi
  accessModes:
    - ReadWriteOnce
  rbd:
    monitors:
    - 10.85.8.118:6789
    - 10.85.8.123:6789
    - 10.85.8.124:6789
    pool: myPool 
    image: image
    user: myPoolUser 
    secretRef:
      name: ceph-user
    fsType: ext4
    readOnly: false
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: ceph-rbd-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi
---
apiVersion: v1
kind: Pod
metadata:
  name: ceph-rbd-pod-pvc-pv
spec:
  containers:
  - name: ceph-rbd-pod-pvc-pv
    image: busybox
    command: ["sleep", "infinity"]
    volumeMounts:
    - mountPath: /mnt/ceph_rbd
      name: volume
  volumes:
  - name: volume
    persistentVolumeClaim:
      claimName: ceph-rbd-pvc
EOF
 
kubectl apply -f ceph-rbd-pod-pvc-pv-allinone.yaml
kubectl get pv,pvc,pod
kubectl exec pod/ceph-rbd-pod-pvc-pv -- df -k | grep rbd

Using RBD in Storage Classes

This example is for dynamic provisioning. The ceph-csi driver is needed.

# pod-pvc-sc
cat > ceph-rbd-pod-pvc-sc-allinone.yaml <<EOF
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: ceph-rbd-sc
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: rbd.csi.ceph.com
parameters:
   clusterID: 79179d9d-98d8-4976-ab2e-58635caa7235
   pool: myPool
   imageFeatures: layering
   csi.storage.k8s.io/provisioner-secret-name: ceph-admin
   csi.storage.k8s.io/provisioner-secret-namespace: default
   csi.storage.k8s.io/controller-expand-secret-name: ceph-admin
   csi.storage.k8s.io/controller-expand-secret-namespace: default
   csi.storage.k8s.io/node-stage-secret-name: ceph-admin
   csi.storage.k8s.io/node-stage-secret-namespace: default
reclaimPolicy: Delete
allowVolumeExpansion: true
mountOptions:
   - discard
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: ceph-rbd-sc-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi
  storageClassName: ceph-rbd-sc
---    
apiVersion: v1
kind: Pod
metadata:
  name: ceph-rbd-pod-pvc-sc
spec:
  containers:
  - name:  ceph-rbd-pod-pvc-sc
    image: busybox
    command: ["sleep", "infinity"]
    volumeMounts:
    - mountPath: /mnt/ceph_rbd
      name: volume
  volumes:
  - name: volume
    persistentVolumeClaim:
      claimName: ceph-rbd-sc-pvc
EOF
 
kubectl apply -f ceph-rbd-pod-pvc-sc-allinone.yaml
kubectl get pv,pvc,sc,pod
kubectl exec pod/ceph-rbd-pod-pvc-sc -- df -k | grep rbd

RKE2 Server/Master Provisioning

sudo su
curl -sfL https://get.rke2.io | sh -
systemctl enable --now rke2-server

cat > /root/.bashrc << EOF
export PATH=$PATH:/var/lib/rancher/rke2/bin/
export KUBECONFIG=/etc/rancher/rke2/rke2.yaml
EOF

cat /var/lib/rancher/rke2/server/node-token
token: K10ca0c38d4ff90d8b80319ab34092e315a8b732622e6adf97bc9eb0536REDACTED::server:ec0308000b8a6b595da000efREDACTED

RKE2 Agent/Worker provisioning

mkdir -p /etc/rancher/rke2/

cat > /etc/rancher/rke2/config.yaml << EOF
server: https://10.100.103.23:9345
token: K10ca0c38d4ff90d8b80319ab34092e315a8b732622e6adf97bc9eb0536REDACTED::server:ec0308000b8a6b595da000efREDACTED
EOF

curl -sfL https://get.rke2.io | INSTALL_RKE2_TYPE="agent" sh -
systemctl enable --now rke2-agent.service

The cluster can be imported into Rancher from the Rancher UI by clicking Global/Add Cluster > Other Cluster. Then run the provided kubectl command on the server/master node.

Tested Versions

OS for running RKE2 nodes: JeOS SLE15-SP2 with installed kernel-default-5.3.18-24.49

kubectl version
Client Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.4", GitCommit:"c96aede7b5205121079932896c4ad89bb93260af", GitTreeState:"clean", BuildDate:"2020-06-22T12:00:00Z", GoVersion:"go1.13.11", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.7+rke2r1", GitCommit:"1dd5338295409edcfff11505e7bb246f0d325d15", GitTreeState:"clean", BuildDate:"2021-01-20T01:50:52Z", GoVersion:"go1.15.5b5", Compiler:"gc", Platform:"linux/amd64"}

helm version
version.BuildInfo{Version:"3.4.1", GitCommit:"c4e74854886b2efe3321e185578e6db9be0a6e29", GitTreeState:"clean", GoVersion:"go1.14.12"}

Kubernetes version on RKE2 cluster: v1.19.7+rke2r1

Troubleshooting

In case you are using SUSE’s ceph-rook based on SES7, it might be useful to expose the monitors on hostNetwork by editing rook-1.4.5/ceph/cluster.yaml and setting spec.network.hostNetwork=true.

Also for operating the ceph-rook cluster, it is useful to deploy a toolbox on the Kubernetes cluster where ceph-rook is provisioned by kubectl apply -f rook-1.4.5/ceph/toolbox.yaml Then all the ceph related commands can be executed in the toolbox pod, for example, by running kubectl exec -it -n rook-ceph rook-ceph-tools-686d8b8bfb-2nvqp -- bash

Operating with the ceph - basic commands:

ceph osd pool stats
ceph osd pool delete myPool myPool --yes-i-really-really-mean-it
rbd list -p myPool
> csi-vol-f5d3766c-7296-11eb-b32a-c2b045952d38
> image

Delete the image: rbd rm csi-vol-f5d3766c-7296-11eb-b32a-c2b045952d38 -p myPool

CephFS commands in rook toolbox:

ceph -s
ceph fs ls
ceph fs fail cephfs
ceph fs rm cephfs --yes-i-really-mean-it
ceph osd pool delete cephfs_data cephfs_data --yes-i-really-really-mean-it
ceph osd pool delete cephfs_metadata cephfs_metadata --yes-i-really-really-mean-it

To prepare a cephfs filesystem, you can run this command on a rook cluster:

kubectl apply -f rook-1.4.5/ceph/filesystem.yaml