Kubernetes resource object introduction and common commands (V) - (NFS & PV & PVC)

Storage abstraction （NFS&PV&PVC）

kubernetes adopt NFS Network file system , Synchronize the attached data of each node , Then it's guaranteed pod Failover, etc , The stored data can still be read .

install NFS

All nodes execute

yum install -y nfs-utils

nfs Master node execution

echo "/nfs/data/ *(insecure,rw,sync,no_root_squash)" > /etc/exports  #  Exposed the directory /nfs/data/,`*` It means that all nodes can access .
mkdir -p /nfs/data
systemctl enable rpcbind --now
systemctl enable nfs-server --now
#  Configuration takes effect 
exportfs -r

#  Check and verify 
[[email protected] ~]# exportfs
/nfs/data      <world>
[[email protected] ~]#

Execute... From node

#  Exhibition 172.31.0.2 Which directories can be mounted 
showmount -e 172.31.0.2  # ip Change to your own master node ip

mkdir -p /nfs/data
#  Mount the local directory and remote directory 
mount -t nfs 172.31.0.2:/nfs/data /nfs/data

#  Write a test file 
echo "hello nfs server" > /nfs/data/test.txt

Actual test

1. Native data mount

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx-pv-demo
  name: nginx-pv-demo
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx-pv-demo
  template:
    metadata:
      labels:
        app: nginx-pv-demo
    spec:
      containers:
      - image: nginx
        name: nginx
        volumeMounts:
        - name: html
          mountPath: /usr/share/nginx/html
      volumes:
        - name: html
          nfs:
            server: 172.31.0.2
            path: /nfs/data/nginx-pv

[[email protected] ~]# kubectl apply -f nfsdata.yml 
deployment.apps/nginx-pv-demo created
[[email protected] ~]#

explain ： Create a directory in the node before deployment mkdir -p /nfs/data/nginx-pv. Use the above method , It realizes the /usr/share/nginx/html The directory is mounted to nfs File system /nfs/data/nginx-pv Catalog , Later revision is very convenient .

2. PV&PVC

PV： Persistent volume （Persistent Volume）, Save the data that the application needs to persist to the specified location .

PVC： Persistent volume declaration （Persistent Volume Claim）, State the persistent volume specifications to be used .

• establish PV pool

Static supply

# nfs Master node execution 
[[email protected] data]# mkdir -p /nfs/data/01
[[email protected] data]# mkdir -p /nfs/data/02
[[email protected] data]# mkdir -p /nfs/data/03
[[email protected] data]# ls
01  02  03  nginx-pv  test.txt
[[email protected] data]# pwd
/nfs/data
[[email protected] data]# 

• establish PV,pv.yml

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv01-10m
spec:
  capacity:
    storage: 10M
  accessModes:
    - ReadWriteMany
  storageClassName: nfs
  nfs:
    path: /nfs/data/01
    server: 172.31.0.2
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv02-1gi
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteMany
  storageClassName: nfs
  nfs:
    path: /nfs/data/02
    server: 172.31.0.2
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv03-3gi
spec:
  capacity:
    storage: 3Gi
  accessModes:
    - ReadWriteMany
  storageClassName: nfs
  nfs:
    path: /nfs/data/03
    server: 172.31.0.2

explain ： take ip Change to yourself nfs The primary node of ip. Here will be our top 3 Folders are created as 3 individual PV, And set the size storage. To form a PV pool . Be careful name No capital letters .

[[email protected] ~]# kubectl apply -f pv.yml 
persistentvolume/pv01-10m created
persistentvolume/pv02-1gi created
persistentvolume/pv03-3gi created
[[email protected] ~]# kubectl get persistentvolume
NAME       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
pv01-10m   10M        RWX            Retain           Available           nfs                     45s
pv02-1gi   1Gi        RWX            Retain           Available           nfs                     45s
pv03-3gi   3Gi        RWX            Retain           Available           nfs                     45s
[[email protected] ~]# 

• establish PVC And PV binding ,pvc.yml

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: nginx-pvc
spec:
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 200Mi
  storageClassName: nfs

Created pvc, The size used is 200Mi. Note here storageClassName Need and pv Keep consistent , It is equivalent to using the same label to find .

[[email protected] ~]# kubectl apply -f pvc.yml 
persistentvolumeclaim/nginx-pvc created
[[email protected] ~]# kubectl get pvc,pv
NAME                              STATUS   VOLUME     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/nginx-pvc   Bound    pv02-1gi   1Gi        RWX            nfs            14m

NAME                        CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM               STORAGECLASS   REASON   AGE
persistentvolume/pv01-10m   10M        RWX            Retain           Available                       nfs                     17m
persistentvolume/pv02-1gi   1Gi        RWX            Retain           Bound       default/nginx-pvc   nfs                     17m
persistentvolume/pv03-3gi   3Gi        RWX            Retain           Available                       nfs                     17m
[[email protected] ~]# 

Can be found using 200Mi Of PVC, Will be in PV The best binding in the pool 1Gi The size of pv02-1gi Of PV To use the , Maximize resource utilization . See at the same time pv In the pool pv02-1gi Of PV Already in use , Status as Bound.

• establish Pod binding PVC,podpvc.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx-deploy-pvc
  name: nginx-deploy-pvc
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx-deploy-pvc
  template:
    metadata:
      labels:
        app: nginx-deploy-pvc
    spec:
      containers:
      - image: nginx
        name: nginx
        volumeMounts:
        - name: html
          mountPath: /usr/share/nginx/html
      volumes:
        - name: html
          persistentVolumeClaim:
            claimName: nginx-pvc

Train of thought ：Pod-->PVC-->PV

[[email protected] ~]# kubectl apply -f podpvc.yml 
deployment.apps/nginx-deploy-pvc created
[[email protected] ~]# 

At this time, we can also modify the file with pod Synchronization within .

Summary

What we said above PV The pool is a static supply . That is, in advance nfs The corresponding file directory is created in , And set the size and so on , for PVC Bind using . There is also a dynamic supply , There is no need to create in advance PV, But according to PVC Requirements for dynamic creation PV, In this way, the utilization of resources is more reasonable and effective .