287 lines
10 KiB
Markdown
287 lines
10 KiB
Markdown
---
|
||
title: 运行一个单实例有状态应用
|
||
content_type: tutorial
|
||
weight: 20
|
||
---
|
||
|
||
<!-- overview -->
|
||
|
||
<!--
|
||
This page shows you how to run a single-instance stateful application
|
||
in Kubernetes using a PersistentVolume and a Deployment. The
|
||
application is MySQL.
|
||
-->
|
||
本文介绍在 Kubernetes 中如何使用 PersistentVolume 和 Deployment 运行一个单实例有状态应用。该应用是 MySQL.
|
||
|
||
## {{% heading "objectives" %}}
|
||
|
||
<!--
|
||
* Create a PersistentVolume referencing a disk in your environment.
|
||
* Create a MySQL Deployment.
|
||
* Expose MySQL to other pods in the cluster at a known DNS name.
|
||
-->
|
||
* 在你的环境中创建一个引用磁盘的 PersistentVolume
|
||
* 创建一个 MySQL Deployment.
|
||
* 在集群内以一个已知的 DNS 名称将 MySQL 暴露给其他 Pod
|
||
|
||
## {{% heading "prerequisites" %}}
|
||
|
||
* {{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
|
||
* {{< include "default-storage-class-prereqs.md" >}}
|
||
|
||
<!-- lessoncontent -->
|
||
|
||
## 部署 MySQL {#deploy-mysql}
|
||
|
||
<!--
|
||
You can run a stateful application by creating a Kubernetes Deployment
|
||
and connecting it to an existing PersistentVolume using a
|
||
PersistentVolumeClaim. For example, this YAML file describes a
|
||
Deployment that runs MySQL and references the PersistentVolumeClaim. The file
|
||
defines a volume mount for /var/lib/mysql, and then creates a
|
||
PersistentVolumeClaim that looks for a 20G volume. This claim is
|
||
satisfied by any existing volume that meets the requirements,
|
||
or by a dynamic provisioner.
|
||
-->
|
||
你可以通过创建一个 Kubernetes Deployment 并使用 PersistentVolumeClaim 将其连接到
|
||
某已有的 PV 卷来运行一个有状态的应用。
|
||
例如，这里的 YAML 描述的是一个运行 MySQL 的 Deployment，其中引用了 PVC 申领。
|
||
文件为 /var/lib/mysql 定义了加载卷，并创建了一个 PVC 申领，寻找一个 20G 大小的卷。
|
||
该申领可以通过现有的满足需求的卷来满足，也可以通过动态供应卷的机制来满足。
|
||
|
||
<!--
|
||
Note: The password is defined in the config yaml, and this is insecure. See
|
||
[Kubernetes Secrets](/docs/concepts/configuration/secret/)
|
||
for a secure solution.
|
||
-->
|
||
注意：在配置的 YAML 文件中定义密码的做法是不安全的。具体安全解决方案请参考
|
||
[Kubernetes Secrets](/zh/docs/concepts/configuration/secret/).
|
||
|
||
{{< codenew file="application/mysql/mysql-deployment.yaml" >}}
|
||
{{< codenew file="application/mysql/mysql-pv.yaml" >}}
|
||
|
||
1. <!--Deploy the PV and PVC of the YAML file-->
|
||
部署 YAML 文件中定义的 PV 和 PVC：
|
||
|
||
```shell
|
||
kubectl apply -f https://k8s.io/examples/application/mysql/mysql-pv.yaml
|
||
```
|
||
|
||
1. <!-- Deploy the contents of the YAML file -->
|
||
部署 YAML 文件中定义的 Deployment：
|
||
|
||
```shell
|
||
kubectl apply -f https://k8s.io/examples/application/mysql/mysql-deployment.yaml
|
||
```
|
||
|
||
1. <!-- Display information about the Deployment -->
|
||
展示 Deployment 相关信息:
|
||
|
||
```shell
|
||
kubectl describe deployment mysql
|
||
```
|
||
|
||
<!--
|
||
The output is similar to this:
|
||
-->
|
||
输出类似于：
|
||
|
||
```
|
||
Name: mysql
|
||
Namespace: default
|
||
CreationTimestamp: Tue, 01 Nov 2016 11:18:45 -0700
|
||
Labels: app=mysql
|
||
Annotations: deployment.kubernetes.io/revision=1
|
||
Selector: app=mysql
|
||
Replicas: 1 desired | 1 updated | 1 total | 0 available | 1 unavailable
|
||
StrategyType: Recreate
|
||
MinReadySeconds: 0
|
||
Pod Template:
|
||
Labels: app=mysql
|
||
Containers:
|
||
mysql:
|
||
Image: mysql:5.6
|
||
Port: 3306/TCP
|
||
Environment:
|
||
MYSQL_ROOT_PASSWORD: password
|
||
Mounts:
|
||
/var/lib/mysql from mysql-persistent-storage (rw)
|
||
Volumes:
|
||
mysql-persistent-storage:
|
||
Type: PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
|
||
ClaimName: mysql-pv-claim
|
||
ReadOnly: false
|
||
Conditions:
|
||
Type Status Reason
|
||
---- ------ ------
|
||
Available False MinimumReplicasUnavailable
|
||
Progressing True ReplicaSetUpdated
|
||
OldReplicaSets: <none>
|
||
NewReplicaSet: mysql-63082529 (1/1 replicas created)
|
||
Events:
|
||
FirstSeen LastSeen Count From SubobjectPath Type Reason Message
|
||
--------- -------- ----- ---- ------------- -------- ------ -------
|
||
33s 33s 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set mysql-63082529 to 1
|
||
```
|
||
|
||
1. <!-- List the pods created by the Deployment -->
|
||
列举出 Deployment 创建的 pods:
|
||
|
||
```shell
|
||
kubectl get pods -l app=mysql
|
||
```
|
||
|
||
<!--
|
||
The output is similar to this:
|
||
-->
|
||
输出类似于：
|
||
|
||
```
|
||
NAME READY STATUS RESTARTS AGE
|
||
mysql-63082529-2z3ki 1/1 Running 0 3m
|
||
```
|
||
|
||
1. <!-- Inspect the PersistentVolumeClaim -->
|
||
查看 PersistentVolumeClaim：
|
||
|
||
```shell
|
||
kubectl describe pvc mysql-pv-claim
|
||
```
|
||
|
||
<!--
|
||
The output is similar to this:
|
||
-->
|
||
输出类似于：
|
||
|
||
```
|
||
Name: mysql-pv-claim
|
||
Namespace: default
|
||
StorageClass:
|
||
Status: Bound
|
||
Volume: mysql-pv-volume
|
||
Labels: <none>
|
||
Annotations: pv.kubernetes.io/bind-completed=yes
|
||
pv.kubernetes.io/bound-by-controller=yes
|
||
Capacity: 20Gi
|
||
Access Modes: RWO
|
||
Events: <none>
|
||
```
|
||
|
||
<!--
|
||
## Accessing the MySQL instance
|
||
|
||
The preceding YAML file creates a service that
|
||
allows other Pods in the cluster to access the database. The Service option
|
||
`clusterIP: None` lets the Service DNS name resolve directly to the
|
||
Pod's IP address. This is optimal when you have only one Pod
|
||
behind a Service and you don't intend to increase the number of Pods.
|
||
|
||
Run a MySQL client to connect to the server:
|
||
-->
|
||
## 访问 MySQL 实例 {#accessing-the-mysql-instance}
|
||
|
||
|
||
前面 YAML 文件中创建了一个允许集群内其他 Pod 访问的数据库服务。该服务中选项
|
||
`clusterIP: None` 让服务 DNS 名称直接解析为 Pod 的 IP 地址。
|
||
当在一个服务下只有一个 Pod 并且不打算增加 Pod 的数量这是最好的.
|
||
|
||
运行 MySQL 客户端以连接到服务器:
|
||
|
||
```
|
||
kubectl run -it --rm --image=mysql:5.6 --restart=Never mysql-client -- mysql -h mysql -ppassword
|
||
```
|
||
|
||
<!--
|
||
This command creates a new Pod in the cluster running a MySQL client
|
||
and connects it to the server through the Service. If it connects, you
|
||
know your stateful MySQL database is up and running.
|
||
-->
|
||
此命令在集群内创建一个新的 Pod 并运行 MySQL 客户端，并通过 Service 连接到服务器。
|
||
如果连接成功，你就知道有状态的 MySQL 数据库正处于运行状态。
|
||
|
||
```
|
||
Waiting for pod default/mysql-client-274442439-zyp6i to be running, status is Pending, pod ready: false
|
||
If you don't see a command prompt, try pressing enter.
|
||
|
||
mysql>
|
||
```
|
||
|
||
<!--
|
||
## Updating
|
||
|
||
The image or any other part of the Deployment can be updated as usual
|
||
with the `kubectl apply` command. Here are some precautions that are
|
||
specific to stateful apps:
|
||
-->
|
||
## 更新 {#updating}
|
||
|
||
Deployment 中镜像或其他部分同往常一样可以通过 `kubectl apply` 命令更新。
|
||
以下是特定于有状态应用的一些注意事项:
|
||
|
||
<!--
|
||
* Don't scale the app. This setup is for single-instance apps
|
||
only. The underlying PersistentVolume can only be mounted to one
|
||
Pod. For clustered stateful apps, see the
|
||
[StatefulSet documentation](/docs/concepts/workloads/controllers/statefulset/).
|
||
* Use `strategy:` `type: Recreate` in the Deployment configuration
|
||
YAML file. This instructs Kubernetes to _not_ use rolling
|
||
updates. Rolling updates will not work, as you cannot have more than
|
||
one Pod running at a time. The `Recreate` strategy will stop the
|
||
first pod before creating a new one with the updated configuration.
|
||
-->
|
||
* 不要对应用进行规模扩缩。这里的设置仅适用于单实例应用。下层的 PersistentVolume
|
||
仅只能挂载到一个 Pod 上。对于集群级有状态应用，请参考
|
||
[StatefulSet 文档](/zh/docs/concepts/workloads/controllers/statefulset/).
|
||
* 在 Deployment 的 YAML 文件中使用 `strategy:` `type: Recreate`。
|
||
该选项指示 Kubernetes _不_ 使用滚动升级。滚动升级无法工作，因为这里一次不能
|
||
运行多个 Pod。在使用更新的配置文件创建新的 Pod 前，`Recreate` 策略将
|
||
保证先停止第一个 Pod。
|
||
|
||
<!--
|
||
## Deleting a deployment
|
||
|
||
Delete the deployed objects by name:
|
||
-->
|
||
## 删除 Deployment {#deleting-a-deployment}
|
||
|
||
通过名称删除部署的对象:
|
||
|
||
```
|
||
kubectl delete deployment,svc mysql
|
||
kubectl delete pvc mysql-pv-claim
|
||
kubectl delete pv mysql-pv-volume
|
||
```
|
||
|
||
<!--
|
||
If you manually provisioned a PersistentVolume, you also need to manually
|
||
delete it, as well as release the underlying resource.
|
||
If you used a dynamic provisioner, it automatically deletes the
|
||
PersistentVolume when it sees that you deleted the PersistentVolumeClaim.
|
||
Some dynamic provisioners (such as those for EBS and PD) also release the
|
||
underlying resource upon deleting the PersistentVolume.
|
||
-->
|
||
如果通过手动的方式供应 PersistentVolume, 那么也需要手动删除它以释放下层资源。
|
||
如果是用动态供应方式创建的 PersistentVolume，在删除 PersistentVolumeClaim 后
|
||
PersistentVolume 将被自动删除。
|
||
一些存储服务（比如 EBS 和 PD）也会在 PersistentVolume 被删除时自动回收下层资源。
|
||
|
||
## {{% heading "whatsnext" %}}
|
||
|
||
<!--
|
||
* Learn more about [Deployment objects](/docs/concepts/workloads/controllers/deployment/).
|
||
|
||
* Learn more about [Deploying applications](/docs/tasks/run-application/run-stateless-application-deployment/)
|
||
|
||
* [kubectl run documentation](/docs/reference/generated/kubectl/kubectl-commands/#run)
|
||
|
||
* [Volumes](/docs/concepts/storage/volumes/) and [Persistent Volumes](/docs/concepts/storage/persistent-volumes/)
|
||
-->
|
||
* 欲进一步了解 Deployment 对象，请参考 [Deployment 对象](/zh/docs/concepts/workloads/controllers/deployment/)
|
||
* 进一步了解[部署应用](/zh/docs/tasks/run-application/run-stateless-application-deployment/)
|
||
|
||
* 参阅 [kubectl run 文档](/docs/reference/generated/kubectl/kubectl-commands/#run)
|
||
|
||
* 参阅[卷](/zh/docs/concepts/storage/volumes/)和[持久卷](/zh/docs/concepts/storage/persistent-volumes/)
|
||
|
||
|