How to use local volume?

General Discussions
1

Cluster information:

Kubernetes version: 1.14.
Cloud being used: bare-metal
Host OS: CentOS 7
CNI and version: Calico
CRI and version: Docker 18.09-CE

Hi, want to run elasticsearch in kubernetes. Since I having trouble running it with glusterFS I want to check it with local storage: Volumes - Kubernetes

As Example following is listed:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: example-pv
spec:
  capacity:
    storage: 100Gi
  # volumeMode field requires BlockVolume Alpha feature gate to be enabled.
  volumeMode: Filesystem
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Delete
  storageClassName: local-storage
  local:
    path: /mnt/disks/ssd1
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - example-node

currently my elasticsearch statefulSet looks like this (currently using glusterFs via storageClass standard):

# statefulset
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: poc-es-master
  labels:
    role: master
    cluster: poc
spec:
  selector:
    matchLabels:
      app: elasticsearch
      role: master
      cluster: poc
  serviceName: poc-es-master
  replicas: 3
  template:
    metadata:
      labels:
        app: elasticsearch
        role: master
        cluster: poc
    spec:
      containers:
      - name: es-master
        image: docker-registry:443/docker.elastic.co/elasticsearch/elasticsearch:7.2.0
        env:
        - name: NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: node.name
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        - name: cluster.name
          value: "poc"
        - name: discovery.seed_hosts
          value: "poc-es-master-0.poc-es-master, poc-es-master-1.poc-es-master, poc-es-master-2.poc-es-master"
        - name: cluster.initial_master_nodes
          value: "poc-es-master-0, poc-es-master-1, poc-es-master-2"
        - name: node.master
          value: "true"
        - name: node.ingest
          value: "true"
        - name: node.data
          value: "true"
        - name: ES_JAVA_OPTS
          value: "-Xms1g -Xmx1g"
        - name: bootstrap.memory_lock
          value: "false"
        - name: network.host
          value: "0.0.0.0"
        - name: PROCESSORS
          valueFrom:
            resourceFieldRef:
              resource: limits.cpu
        resources:
          requests:
            cpu: 0.25
            memory: 1Gi
          limits:
            cpu: 2
            memory: 4Gi
        ports:
        - containerPort: 9300
          name: transport
        - containerPort: 9200
          name: http
        livenessProbe:
          tcpSocket:
            port: transport
          initialDelaySeconds: 20
          periodSeconds: 10
        volumeMounts:
        - name: storage
          mountPath: /usr/share/elasticsearch/data
        - name: backup-storage
          mountPath: /usr/share/elasticsearch/snapshots
      volumes:
        - name: backup-storage
          persistentVolumeClaim:
            claimName: nfs-elastic-backup-qdetjt
  volumeClaimTemplates:
  - metadata:
      name: storage
    spec:
      storageClassName: standard
      accessModes: [ ReadWriteOnce ]
      resources:
        requests:
          storage: 30Gi

I have a few questions about the local storage and it’s example:

  • As I understand it, the local storage is working with block devices.
    • Do I need to partition and format this device before I can use it?
    • In node affinity I can define one or more hostnames of my kubernetes nodes if I understand correctly. What Do I need to do if I have different devices available per node?
      e.g:
      node1: -> /dev/sdb
      node2: -> /dev/sdc and /dev/sdd
      How do I need to specify it?
  • Do I need one PV with one PVC per elasticsearch pod (1PV to 1 PVC) or will multiple pods create their own PVC on a shared PV (1 PV to many PVC)?
  • How do I specify the local storage in the volumeClaimTemplate of the statefulSet?
    • just changing the storage class in my volumeClaimTemplate to local-storage?
    • could you provide any example with local storage and a statefulSet?

Thanks, Andreas