容器开启数据服务之旅系列（一）：Kubernetes如何解自建PostgreSQL运维之痛

容器开启数据服务之旅系列（一）：Kubernetes如何解自建PostgreSQL运维之痛

概述

本文为大家介绍一种容器化的数据服务 posgresql db on ACK，通过使用云盘自动挂载实现的块存储PVC来做到数据库的免运维恢复。借助阿里云Kubernetes服务与阿里云存储资源的深度整合，打造数据库实例的免运维异地（ECS）恢复的不死神话。

先决条件

1. 你已经通过阿里云容器服务创建了一个Kubernetes集群，详细步骤参见创建Kubernetes集群
2. 阿里云容器服务的存储插件（默认情况存储插件已经自动部署在阿里云Kubernetes容器服务）

从容器服务控制台创建一个posgresql实例

使用三次点击来创建一个postgresql的不死实例

1. 登录 https://cs.console.aliyun.com/
2. 点击 “应用目录”
3. 选择 "postgresql"



4 （可选）选择你的Kubernetes集群. e.g. k8s-gpu
5 （可选）选择你的应用的命名空间。默认: default
6 给你的数据库应用取个容易记住的名字。 e.g. postgresql-online



7 (可选) 点击 “参数” 来定制你的数据库实例

1. 修改 persistence.size: 20Gi 增加数据库云盘的容量
2. 修改 persistence.storageClass: alicloud-disk-efficiency 调整数据卷所在云盘的性能。比如改为alicloud-disk-ssd 挂载ssd类型的



## Persist data to a persitent volume
persistence:
  enabled: true

  ## A manually managed Persistent Volume and Claim
  ## Requires persistence.enabled: true
  ## If defined, PVC must be created manually before volume will be bound
  # existingClaim:

  ## database data Persistent Volume Storage Class
  ## if defined, user has to define storageClassName: alicloud-disk to support dynamic provision of alicloud-disk
  ## If defined, storageClassName: <storageClass>
  ## If set to "-", storageClassName: "", which disables dynamic provisioning
  ## If undefined (the default) or set to null, no storageClassName spec is
  ##   set, choosing the default provisioner.  (gp2 on AWS, standard on
  ##   GKE, AWS & OpenStack)
  ##
  #storageClass: "alicloud-disk-ssd"
  storageClass: "alicloud-disk-efficiency"
  accessMode: ReadWriteOnce
  size: 20Gi
  subPath: "postgresql-db"

8 点击 “部署”， 完成数据发布
9 点击 “Kubernetes 控制台”，查看部署实例


10 点击容器组，点击 postgresql-online-postgresql 查看数据库实例密码。容器实例启动在节点:cn-hangzhou.i-bp1fazljd8u2ylk2otdo





11 测试postgresql数据库的异地(ECS)恢复

1. 添加测试数据

ssh <public ip of kubernetes master node >`

# kubectl run my-pg-postgresql-client --rm --tty -i --image postgres \
--env "PGPASSWORD=$PGPASSWORD" \
--command -- psql -U postgres \
-h postgresql-online-postgresql  postgres

If you don't see a command prompt, try pressing enter.

postgres=# create table t1 (id int);
CREATE TABLE
postgres=# insert into t1 values(10);
INSERT 0 1
postgres=# select * from t1;
 id
----
 10
(1 row)

1. 驱逐数据库实例从ECS节点 i-bp1fazljd8u2ylk2otdo 到 i-bp1fazljd8u2ylk2otdp

#kubectl get pod -o wide | grep postgresql-online-postgresql
postgresql-online-postgresql-78884fbcf6-6mfzz    1/1       Running   0          36m       172.30.4.4   cn-hangzhou.i-bp1fazljd8u2ylk2otdo

#kubectl cordon cn-hangzhou.i-bp1fazljd8u2ylk2otdo 

#kubectl delete pod postgresql-online-postgresql-78884fbcf6-6mfzz
pod "postgresql-online-postgresql-78884fbcf6-6mfzz" deleted
# kubectl get pod -o wide|grep postgresql-online-postgresql
#postgresql-online-postgresql-78884fbcf6-87ttg    0/1       Running   0          15s       172.30.3.5   cn-hangzhou.i-bp1fazljd8u2ylk2otdp

1. 检验数据，实例迁移， 数据库实例自动化恢复， 数据不丢失。

# kubectl get pod -o wide|grep postgresql-online-postgresql
#postgresql-online-postgresql-78884fbcf6-87ttg    0/1       Running   0          15s       172.30.3.5   cn-hangzhou.i-bp1fazljd8u2ylk2otdp

kubectl run my-pg-postgresql-client --rm --tty -i --image postgres \
> --env "PGPASSWORD=$PGPASSWORD" \
> --command -- psql -U postgres \
> -h postgresql-online-postgresql  postgres
If you don't see a command prompt, try pressing enter.
postgres=# select * from t1;
 id
----
 10
(1 row)

CLI控: 使用命令行完成postgresql实例的创建，迁移验证

login k8s master and deploy an postgresql db in seconds.

ssh <public ip of kubernetes master node >

helm install -n postgresql-online --set 'persistence.size=30Gi,persistence.storageClass=alicloud-disk-ssd' stable/postgresql

To get your user password run:

PGPASSWORD=$(kubectl get secret --namespace default my-pg-postgresql -o jsonpath="{.data.postgres-password}" | base64 --decode; echo)

To connect to your database run the following command (using the env variable from above):

   kubectl run my-pg-postgresql-client --rm --tty -i --image postgres \
   --env "PGPASSWORD=$PGPASSWORD" \
   --command -- psql -U postgres \
   -h postgresql-online-postgresql  postgres

To connect to your database directly from outside the K8s cluster:

 PGHOST=127.0.0.1
 PGPORT=5432

 # Execute the following commands to route the connection:
 export POD_NAME=$(kubectl get pods --namespace default -l "app=my-pg-postgresql" -o jsonpath="{.items[0].metadata.name}")
 kubectl port-forward $POD_NAME 5432:5432

#kubectl get pod -o wide | grep postgresql-online-postgresql
postgresql-online-postgresql-78884fbcf6-6mfzz    1/1       Running   0          36m       172.30.4.4   cn-hangzhou.i-bp1fazljd8u2ylk2otdo

#kubectl cordon cn-hangzhou.i-bp1fazljd8u2ylk2otdo 

#kubectl delete pod postgresql-online-postgresql-78884fbcf6-6mfzz
pod "postgresql-online-postgresql-78884fbcf6-6mfzz" deleted
# kubectl get pod -o wide|grep postgresql-online-postgresql
#postgresql-online-postgresql-78884fbcf6-87ttg    0/1       Running   0          15s       172.30.3.5   cn-hangzhou.i-bp1fazljd8u2ylk2otdp

Test original postgresql db could be recovered on different node.

#kubectl get pod -o wide|grep postgresql-online-postgresql
#postgresql-online-postgresql-78884fbcf6-87ttg    0/1       Running   0          15s       172.30.3.5   cn-hangzhou.i-bp1fazljd8u2ylk2otdp

kubectl run my-pg-postgresql-client --rm --tty -i --image postgres \
> --env "PGPASSWORD=$PGPASSWORD" \
> --command -- psql -U postgres \
> -h postgresql-online-postgresql  postgres
If you don't see a command prompt, try pressing enter.
postgres=# select * from t1;
 id
----
 10
(1 row)