k8s使用openebs实现动态持久化存储

简介

本文章介绍如何使用openebs为k8s提供动态申请pv的功能。iscsi提供底层存储功能，openebs管理iscsi。目前只支持pv的ReadWriteOnce访问模式

访问模式只是能力描述，并不是强制执行的，对于没有按pvc 声明的方式使用pv，存储提供者应该负责访问时的运行错误。例如如果设置pvc的访问模式为ReadOnlyMany ，pod挂载后依然可写，如果需要真正的不可写，申请pvc是需要指定 readOnly: true 参数

安装

实验用的Vagrantfile

# -*- mode: ruby -*- # vi: set ft=ruby :

ENV["LC_ALL"] = "en_US.UTF-8"

Vagrant.configure("2") do |config|
 (1..3).each do |i|
 config.vm.define "lab#{i}" do |node|
 node.vm.box = "centos-7.4-docker-17"
 node.ssh.insert_key = false
 node.vm.hostname = "lab#{i}"
 node.vm.network "private_network", ip: "11.11.11.11#{i}"
 node.vm.provision "shell",
 inline: "echo hello from node #{i}"
 node.vm.provider "virtualbox" do |v|
 v.cpus = 2
 v.customize ["modifyvm", :id, "--name", "lab#{i}", "--memory", "3096"]
 file_to_disk = "lab#{i}_vdb.vdi"
 unless File.exist?(file_to_disk)
 # 50GB
 v.customize ['createhd', '--filename', file_to_disk, '--size', 50 * 1024]
 end
 v.customize ['storageattach', :id, '--storagectl', 'IDE', '--port', 1, '--device', 0, '--type', 'hdd', '--medium', file_to_disk]
 end
 end
 end
end
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安装配置iscsi

# 安装 iscsi
yum install iscsi-initiator-utils -y

# 查看 InitiatorName 是否正常配置
cat /etc/iscsi/initiatorname.iscsi

# 启动查看状态
systemctl start iscsid.service
systemctl status iscsid.service

systemctl start iscsi.service
systemctl status iscsi.service
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安装openebs

# 部署
mkdir openebs && cd openebs
wget https://raw.githubusercontent.com/openebs/openebs/v0.6/k8s/openebs-operator.yaml
wget https://raw.githubusercontent.com/openebs/openebs/v0.6/k8s/openebs-storageclasses.yaml
kubectl apply -f openebs-operator.yaml
kubectl apply -f openebs-storageclasses.yaml

# 查看 openebs 状态
kubectl get pods -n openebs -o wide
kubectl get svc -n openebs
kubectl get crd
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测试

# 查看 storage class
kubectl get sc

# 创建pvc测试
cat >openebs-pvc-test.yaml<<EOF
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
 name: openebs1
spec:
 storageClassName: openebs-standard
 accessModes:
 - ReadWriteOnce
 resources:
 requests:
 storage: 5Gi
EOF
kubectl apply -f openebs-pvc-test.yaml
 
# 查看
kubectl get pvc
kubectl get pv
 
# 创建 nginx pod 挂载测试
cat >nginx-pod.yaml<<EOF
apiVersion: v1
kind: Pod
metadata:
 name: nginx-pod1
 labels:
 name: nginx-pod1
spec:
 containers:
 - name: nginx-pod1
 image: nginx:alpine
 ports:
 - name: web
 containerPort: 80
 volumeMounts:
 - name: openebs1-vol1
 mountPath: /usr/share/nginx/html
 volumes:
 - name: openebs1-vol1
 persistentVolumeClaim:
 claimName: openebs1
EOF
kubectl apply -f nginx-pod.yaml
 
# 查看
kubectl get pods -o wide
 
# 修改文件内容
kubectl exec -ti nginx-pod1 -- /bin/sh -c 'echo Hello World from Openebs!!! > /usr/share/nginx/html/index.html' # 访问测试
POD_ID=$(kubectl get pods -o wide | grep nginx-pod1 | awk '{print $(NF-1)}')
curl http://$POD_ID