尝试使用Persistent Volumes教程
尝试以下教程时的笔记。
部署使用持久卷的WordPress和MySQL。
自然氛圍
-
- クラスター作成済み(minikube ではない）
- kubectl コマンド設定済み
# バージョン情報
$kubectl version
Client Version: version.Info{Major:"1", Minor:"10", GitVersion:"v1.10.3", GitCommit:"2bba0127d85d5a46ab4b778548be28623b32d0b0", GitTreeState:"clean", BuildDate:"2018-05-28T20:03:09Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"10", GitVersion:"v1.10.3", GitCommit:"2bba0127d85d5a46ab4b778548be28623b32d0b0", GitTreeState:"clean", BuildDate:"2018-05-28T20:13:43Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"linux/amd64"}
# ノードもクラスターに参加済み
$kubectl get nodes
NAME STATUS ROLES AGE VERSION
ip-192-168-111-32.us-west-2.compute.internal Ready <none> 40d v1.10.3
ip-192-168-150-4.us-west-2.compute.internal Ready <none> 40d v1.10.3
ip-192-168-194-26.us-west-2.compute.internal Ready <none> 40d v1.10.3
试一试
开始之前
由于本章的主要内容是要求创建一个集群，请略过本次任务，因为已经提前准备好了。
创建持久化卷声明和持久化卷
许多群集环境都预装有默认的StorageClass。当PersistentVolumeClaim中没有指定StorageClass时，将使用群集的默认StorageClass代替。
如果在PersistentVolumeClaim中没有提及StorageClass，就会使用默认的StorageClass来进行资源供应。请检查默认的StorageClass。
# StorageClass が2つ定義されており、「gp2」がデフォルトとなっている
$kubectl get storageclass
NAME PROVISIONER AGE
gp2 (default) kubernetes.io/aws-ebs 6d
gp2-2 kubernetes.io/aws-ebs 4d
我已确认在我的环境中已经设置了默认的 StorageClass，所以可以继续进行下去。
创建一个MySQL密码的秘密
创建用于MySQL密码的Secrets。
以下是Secret的详细信息。
# secret を作成する
$kubectl create secret generic mysql-pass --from-literal=password=YOUR_PASSWORD
secret "mysql-pass" created
# mysql-pass という secret が作成されている点を確認
$kubectl get secrets
NAME TYPE DATA AGE
default-token-9jhrf kubernetes.io/service-account-token 3 41d
mysql-pass Opaque 1 21s
部署MySQL
部署MySQL
apiVersion: v1
kind: Service
metadata:
name: wordpress-mysql
labels:
app: wordpress
spec:
ports:
- port: 3306
selector:
app: wordpress
tier: mysql
clusterIP: None
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: mysql-pv-claim
labels:
app: wordpress
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 20Gi
---
apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
name: wordpress-mysql
labels:
app: wordpress
spec:
selector:
matchLabels:
app: wordpress
tier: mysql
strategy:
type: Recreate
template:
metadata:
labels:
app: wordpress
tier: mysql
spec:
containers:
- image: mysql:5.6
name: mysql
env:
- name: MYSQL_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mysql-pass
key: password
ports:
- containerPort: 3306
name: mysql
volumeMounts:
- name: mysql-persistent-storage
mountPath: /var/lib/mysql
volumes:
- name: mysql-persistent-storage
persistentVolumeClaim:
claimName: mysql-pv-claim
-
- Service, PersistentVolumeClaim, Deploymentを kind で定義
-
- 環境変数で先ほど作成した secret の「MYSQL_ROOT_PASSWORD」を利用
- PersistentVolumeClaim を定義し、20GB のストレージを要求。また、MySQL では PersistentVolume を「/var/lib/mysql」にマウントする
那么就开始部署吧。
# Service, PersistentVolumeClaim, Deploymentを作成
$kubectl create -f https://k8s.io/examples/application/wordpress/mysql-deployment.yaml
service "wordpress-mysql" created
persistentvolumeclaim "mysql-pv-claim" created
deployment.apps "wordpress-mysql" created
# PersistentVolumeClaim の作成を確認
$ kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
mysql-pv-claim Bound pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c 20Gi RWO gp2 17s
# PersistentVolume の作成も確認。CLAIM 列が「mysql-pv-claim」となっている
$kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c 20Gi RWO Retain Bound default/mysql-pv-claim gp2 1m
# デプロイしたので MySQL の Pod の起動も確認
$kubectl get pods
NAME READY STATUS RESTARTS AGE
wordpress-mysql-bcc89f687-bjb6g 1/1 Running 0 2m
# descibe コマンドで詳細を見るとボリュームがアタッチされたことが確認出来る。
$kubectl describe pods wordpress-mysql-bcc89f687-bjb6g |less
(一部省略)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedScheduling 6m (x5 over 6m) default-scheduler pod has unbound PersistentVolumeClaims (repeated 3 times)
Normal Scheduled 6m default-scheduler Successfully assigned wordpress-mysql-bcc89f687-bjb6g to ip-192-168-194-26.us-west-2.compute.internal
Normal SuccessfulMountVolume 6m kubelet, ip-192-168-194-26.us-west-2.compute.internal MountVolume.SetUp succeeded for volume "default-token-9jhrf"
Normal SuccessfulAttachVolume 6m attachdetach-controller AttachVolume.Attach succeeded for volume "pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c"
Normal SuccessfulMountVolume 6m kubelet, ip-192-168-194-26.us-west-2.compute.internal MountVolume.SetUp succeeded for volume "pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c"
Normal Pulled 6m kubelet, ip-192-168-194-26.us-west-2.compute.internal Container image "mysql:5.6" already present on machine
Normal Created 6m kubelet, ip-192-168-194-26.us-west-2.compute.internal Created container
Normal Started 6m kubelet, ip-192-168-194-26.us-west-2.compute.internal Started container
# インスタンスにログインして確認。xvdf が見える
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 20G 0 disk
└─xvda1 202:1 0 20G 0 part /
xvdbf 202:14592 0 20G 0 disk /var/lib/kubelet/pods/cfebfda3-897d-11e8-a565-
# dokcer inspect で見ると /varlib/mysql として xvdf がマウントされているのが分かる
$docker inspect 1a25629da4ca |less
(一部省略)
"Mounts": [
{
"Type": "bind",
"Source": "/var/lib/kubelet/pods/cfebfda3-897d-11e8-a565-06fc7dc53c2c/volumes/kubernetes.io~aws-ebs/pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c",
"Destination": "/var/lib/mysql",
"Mode": "",
"RW": true,
"Propagation": "rprivate"
},
看起来不错，我决定继续下一步。
部署WordPress
apiVersion: v1
kind: Service
metadata:
name: wordpress
labels:
app: wordpress
spec:
ports:
- port: 80
selector:
app: wordpress
tier: frontend
type: LoadBalancer
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: wp-pv-claim
labels:
app: wordpress
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 20Gi
---
apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
name: wordpress
labels:
app: wordpress
spec:
selector:
matchLabels:
app: wordpress
tier: frontend
strategy:
type: Recreate
template:
metadata:
labels:
app: wordpress
tier: frontend
spec:
containers:
- image: wordpress:4.8-apache
name: wordpress
env:
- name: WORDPRESS_DB_HOST
value: wordpress-mysql
- name: WORDPRESS_DB_PASSWORD
valueFrom:
secretKeyRef:
name: mysql-pass
key: password
ports:
- containerPort: 80
name: wordpress
volumeMounts:
- name: wordpress-persistent-storage
mountPath: /var/www/html
volumes:
- name: wordpress-persistent-storage
persistentVolumeClaim:
claimName: wp-pv-claim
-
- Service, PersistentVolumeClaim, Deploymentを kind で定義
- PersistentVolumeClaim を定義し、20GB のストレージを要求。また、WordPress では PersistentVolume を「/var/www/html」にマウントする
部署。
# Service, PersistentVolumeClaim, Deploymentを作成
$kubectl create -f https://k8s.io/examples/application/wordpress/wordpress-deployment.yaml
service "wordpress" created
persistentvolumeclaim "wp-pv-claim" created
deployment.apps "wordpress" created
# wp-pv-claim が増えている
$ kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
mysql-pv-claim Bound pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c 20Gi RWO gp2 26m
wp-pv-claim Bound pvc-6ad87529-8981-11e8-971c-022ca775d168 20Gi RWO gp2 29s
# pv も増えている
$kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-6ad87529-8981-11e8-971c-022ca775d168 20Gi RWO Retain Bound default/wp-pv-claim gp2 4m
pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c 20Gi RWO Retain Bound default/mysql-pv-claim gp2 30m
# service の URL を取得
$ kubectl describe services wordpress
Name: wordpress
Namespace: default
Labels: app=wordpress
Annotations: <none>
Selector: app=wordpress,tier=frontend
Type: LoadBalancer
IP: 10.100.124.11
LoadBalancer Ingress: a6ac6da84898111e8971c022ca775d16-182335252.us-west-2.elb.amazonaws.com
Port: <unset> 80/TCP
TargetPort: 80/TCP
NodePort: <unset> 30000/TCP
Endpoints: 192.168.191.64:80
Session Affinity: None
External Traffic Policy: Cluster
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal EnsuringLoadBalancer 2m service-controller Ensuring load balancer
Normal EnsuredLoadBalancer 2m service-controller Ensured load balancer
确认在浏览器中访问”http://a6ac6da84898111e8971c022ca775d16-182335252.us-west-2.elb.amazonaws.com/”时，会显示WordPress界面。
清理干净
檢証完成後，請刪除。
# secret を削除する
$kubectl delete secret mysql-pass
secret "mysql-pass" deleted
# deploymnet と service を削除する -l は Selector (label query)。どちらにも app=wordpress のラベル付がされているので削除できる
$kubectl delete deployment -l app=wordpress
deployment.extensions "wordpress" deleted
deployment.extensions "wordpress-mysql" deleted
$kubectl delete service -l app=wordpress
service "wordpress" deleted
service "wordpress-mysql" deleted
# ラベル付けされた PersistentVolumeClaims も削除
$kubectl delete pvc -l app=wordpress
persistentvolumeclaim "mysql-pv-claim" deleted
persistentvolumeclaim "wp-pv-claim" deleted
# pvc は削除された
$kubectl get pvc
No resources found.
然而，在设置为默认的 StorageClass 中，如果策略是“保留”，即使删除了pvc，pv仍然存在。
这可以通过更改pv的策略来解决。
修改持久卷的回收策略
# POLICY が Retain なので pvc がなくても残っている
$kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-6ad87529-8981-11e8-971c-022ca775d168 20Gi RWO Retain Released default/wp-pv-claim gp2 11m
pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c 20Gi RWO Retain Released default/mysql-pv-claim gp2 37m
# patch で poilicy を変える
$kubectl patch pv pvc-6ad87529-8981-11e8-971c-022ca775d168 -p '{"spec": {"persistentVolumeReclaimPolicy":"Delete"}}'
persistentvolume "pvc-6ad87529-8981-11e8-971c-022ca775d168" patched
# 既に pvc がないので削除される
$kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c 20Gi RWO Retain Released default/mysql-pv-claim gp2 41m
# 同じように対応
$ kubectl patch pv pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c -p '{"spec": {"persistentVolumeReclaimPolicy":"Delete"}}'
persistentvolume "pvc-cfd92d33-897d-11e8-a565-06fc7dc53c2c" patched
$kubectl get pv
No resources found.
结束了。
