基于生成环境tomcat的Kubernetes的deployment使用

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Deployment管理Pods和ReplicaSets，提供声明式更新。和老的ReplicationController（命令式管理）对应，发展趋势是取代老的，所以后面也不会起文章单独讨论ReplicationController了。

但由Deployment-controller管理的Pods和ReplicaSets最好自始至终都由Deployment-controller管理，最好不要手动去管理，以免发生冲突。

创建Deployment

如下一个Deployment的配置（tomcat-deployment.yaml），创建一个ReplicaSet包含3个tomcat Pods

apiVersion: apps/v1
kind: Deployment
metadata:
 name: tomcat-deployment
 labels:
 app: tomcat
spec:
 replicas: 1
 selector:
 matchLabels:
 app: tomcat
 template:
 metadata:
 labels:
 app: tomcat
 spec:
 containers:
 - name: tomcat
 image: 10.209.3.81/library/os7tom7jdk8:v1.0
 command: [/root/run.sh]
 resources: {}
 imagePullPolicy: IfNotPresent
 ports:
 - containerPort: 8080

 

  • apiVersion这里为apps/v1，如果是1.9之前的版本为extensions/v1beta1
  • replicas:3 起3个replicated Pods
  • selector指明哪个pod被管理，这里我们指定了label（app:nginx）
  • template: spec 指明了运行一个容器tomcat（以自己制作的镜像为例）
  • 开放8080端口给container，以使container之间能发送和接收流量

注意这里定义name 或 label 时不要和其他的重复，k8s不会检查这个，需要人工自己确认

要创建此部署，执行下面的命令（在这之前我们提前下好nginx相关的镜像，docker pull nginx:1.7.9，我这里是使用自己的镜像库，请参考：docker镜像库搭建）

[root@master yaml]# kubectl create -f tomcat-deployment.yaml --record
deployment "tomcat-deployment" created
  • --record会记录操作历史，以便于后面回滚操作

查看deployments

[root@k4614v /data/yaml]# kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
tomcat-deployment 3 3 3 3 2h
  • NAME：在集群中的部署名称
  • DESIRED：显示配置里定义的副本数量，这是应该达到的副本数量
  • CURRENT：当前正在运行的副本数量
  • UP-TO-DATE：更新到当前所需状态的副本数量
  • AVAILABLE：可供使用的副本数量
  • AEG：显示app存活的时间

这里注意如果定义了.spec.minReadySeconds，那么必须经过定义的时间才会达到AVAILABLE 状态

通过下面语句可查追踪部署情况

[root@k4614v /data/yaml]# kubectl rollout status deployment/tomcat-deployment
deployment "tomcat-deployment" successfully rolled out

通过下面的命令查看Deployment创建的ReplicaSet（rs）

[root@k4614v /data/yaml]# kubectl get rs
NAME DESIRED CURRENT READY AGE
tomcat-deployment-5cd68b69d 3 3 3 2h

注意ReplicaSet的名称格式为[DEPLOYMENT-NAME]-[POD-TEMPLATE-HASH-VALUE]，后面的hash值是由Deployment自动创建的

查看Pods

[root@k4614v /data/yaml]# kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
tomcat-deployment-5cd68b69d-9wnjn 1/1 Running 0 1h app=tomcat,pod-template-hash=178246258
tomcat-deployment-5cd68b69d-k4ffb 1/1 Running 0 2h app=tomcat,pod-template-hash=178246258
tomcat-deployment-5cd68b69d-vxzjd 1/1 Running 0 1h app=tomcat,pod-template-hash=178246258

创建的ReplicaSet 会确保时刻有3个nginx Pods的副本在运行

 

更新Deployment

假设我们想把tomcat更新到正式的appupdate2018418，有以下3种方式

1. 直接set命令设置变更的部分

$ kubectl set image deployment/tomcat-deployment tomcat=10.209.3.81/library/appupdate2018418:v2
deployment "tomcat-deployment" image updated

以上命令会自动回滚更改Pods，即停止一定量的老的，新建新的，直到来的终止完，新的启动完

通过describe即可查看所有的细节

[root@k4152v /data/yaml]# kubectl describe deployment/tomcat-deployment
Name: tomcat-deployment
Namespace: default
CreationTimestamp: Thu, 12 Apr 2018 14:54:49 +0800
Labels: app=tomcat
Annotations: deployment.kubernetes.io/revision=6
 kubernetes.io/change-cause=kubectl set image deployment/tomcat-deployment tomcat=10.209.3.81/library/appupdate2018418:v3
Selector: app=tomcat
Replicas: 3 desired | 2 updated | 4 total | 3 available | 1 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:
 Labels: app=tomcat
 Containers:
 tomcat:
 Image: 10.209.3.81/library/appupdate2018418:v3
 Port: 8080/TCP
 Command:
 /root/run.sh
 Environment: <none>
 Mounts: <none>
 Volumes: <none>
Conditions:
 Type Status Reason
 ---- ------ ------
 Available True MinimumReplicasAvailable
 Progressing True ReplicaSetUpdated
OldReplicaSets: tomcat-deployment-5cd68b69d (2/2 replicas created)
NewReplicaSet: tomcat-deployment-799f9cc9 (2/2 replicas created)
Events:
 Type Reason Age From Message
 ---- ------ ---- ---- -------
 Normal ScalingReplicaSet 7m deployment-controller Scaled up replica set tomcat-deployment-7d5fd4b5d6 to 1
 Normal DeploymentRollback 4m deployment-controller Rolled back deployment "tomcat-deployment" to revision 3
 Normal ScalingReplicaSet 4m deployment-controller Scaled down replica set tomcat-deployment-7d5fd4b5d6 to 0
 Normal ScalingReplicaSet 18s deployment-controller Scaled up replica set tomcat-deployment-799f9cc9 to 1
 Normal ScalingReplicaSet 14s deployment-controller Scaled down replica set tomcat-deployment-5cd68b69d to 2
 Normal ScalingReplicaSet 14s deployment-controller Scaled up replica set tomcat-deployment-799f9cc9 to 2
  • 可见image已经变了
  • 另外Events可查看滚动更新的过程
  • 另外上面的说的停止和新建的比例在这里体现RollingUpdateStrategy:  25% max unavailable, 25% max surge，25% max unavailable确保在更新时只有部分会关闭（这里是pod数的25%会关闭）。25% max surge确保创建新的pod也在一定比例上（这里默认也是25%）

2. 通过直接修改线上的配置也可直接修改

kubectl edit deployment/tomcat-deployment

会打开一个编辑器，修改指定的部分即可，这里是.spec.template.spec.containers[0].image

3. 修改yaml文件，通过apply重新部署

[root@master yaml]# kubectl apply -f tomcat-deployment.yaml 
Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
deployment "tomcat-deployment" configured

但这里有个警告: 也就是apply方式更新的资源应该是由kubectl create 加--save-config参数创建的 或 由apply创建的 （apply当资源不存在时会创建）

这时我们查看rs，会显示新起了一个rs并将副本扩到3个，旧的rs都缩减为0

[root@k4152v /data/yaml]# kubectl get rs
NAME DESIRED CURRENT READY AGE
tomcat-deployment-587854b948 0 0 0 5d
tomcat-deployment-5cd68b69d 0 0 0 6d
tomcat-deployment-799f9cc9 3 3 3 1h
tomcat-deployment-7d5fd4b5d6 0 0 0 1h

 

回滚Deployment

有时需要回滚的操作，比如发版本的时候docker镜像出问题了

比如上面的操作更新到10.209.3.81/library/appupdate2018418:v2

[root@master yaml]# kubectl set image deployment/tomcat-deployment tomcat=10.209.3.81/library/appupdate2018418:v2
deployment "tomcat-deployment" image updated

追踪状态

[root@master yaml]# kubectl rollout status deployments tomcat-deployment
Waiting for rollout to finish: 1 out of 3 new replicas have been updated...

可见卡住不动了， Ctrl+C终止，查看rs如下

[root@k4152v /data/yaml]# kubectl get rs
NAME DESIRED CURRENT READY AGE
tomcat-deployment-587854b948 0 0 0 5d
tomcat-deployment-5cd68b69d 0 0 0 6d
tomcat-deployment-799f9cc9 3 3 3 1h
tomcat-deployment-7d5fd4b5d6 0 0 0 1h

新的rs只启动了Pod但没有处于READY状态

查看Pods

[root@k4152v /data/yaml]# kubectl get pods
NAME READY STATUS RESTARTS AGE
tomcat-deployment-799f9cc9-9mmwv 1/1 Running 0 16m
tomcat-deployment-799f9cc9-hz2nv 1/1 Running 0 16m
tomcat-deployment-799f9cc9-mf4z2 1/1 Running 0 16m

可发现ImagePullBackOff，实际就是镜像不存在

要修复这个，我们就需要rollback到前一个ok的版本

查看操作历史

[root@k4152v /data/yaml]# kubectl rollout history deployment/tomcat-deployment
deployments "tomcat-deployment"
REVISION CHANGE-CAUSE
2 kubectl set image deployment/tomcat-deployment tomcat=10.209.3.81/library/appupdate20180413:v1.0
4 kubectl set image deployment/tomcat-deployment tomcat=10.209.3.81/library/appupdate2018418:v2
7 kubectl set image deployment/tomcat-deployment tomcat=10.209.3.81/library/os7tom7jdk8:v1.0
8 kubectl set image deployment/tomcat-deployment tomcat=10.209.3.81/library/appupdate2018418:v3

要查看每个版本的详细情况，指定--revision

[root@k4152v /data/yaml]# kubectl rollout history deployment/tomcat-deployment --revision=4
deployments "tomcat-deployment" with revision #4
Pod Template:
 Labels: app=tomcat
 pod-template-hash=3819806182
 Annotations: kubernetes.io/change-cause=kubectl set image deployment/tomcat-deployment tomcat=10.209.3.81/library/appupdate2018418:v2
 Containers:
 tomcat:
 Image: 10.209.3.81/library/appupdate2018418:v2
 Port: 8080/TCP
 Command:
 /root/run.sh
 Environment: <none>
 Mounts: <none>
 Volumes: <none>

接下来进行回滚的操作

不指定版本，默认回滚到上一个版本

[root@master yaml]# kubectl rollout undo deployment/tomcat-deployment
deployment "tomcat-deployment" rolled back

指定版本，通过--to-revision指定

[root@master yaml]# kubectl rollout undo deployment/tomcat-deployment --to-revision=6
deployment "nginx-deployment" rolled back

查看

[root@k4152v /data/yaml]# kubectl describe deployment/tomcat-deployment
Name: tomcat-deployment
Namespace: default
CreationTimestamp: Thu, 12 Apr 2018 14:54:49 +0800
Labels: app=tomcat
Annotations: deployment.kubernetes.io/revision=8
 kubernetes.io/change-cause=kubectl set image deployment/tomcat-deployment tomcat=10.209.3.81/library/appupdate2018418:v3
Selector: app=tomcat
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:
 Labels: app=tomcat
 Containers:
 tomcat:
 Image: 10.209.3.81/library/appupdate2018418:v3
 Port: 8080/TCP
 Command:
 /root/run.sh
 Environment: <none>
 Mounts: <none>
 Volumes: <none>
Conditions:
 Type Status Reason
 ---- ------ ------
 Available True MinimumReplicasAvailable
 Progressing True NewReplicaSetAvailable
OldReplicaSets: <none>
NewReplicaSet: tomcat-deployment-799f9cc9 (3/3 replicas created)
Events:
 Type Reason Age From Message
 ---- ------ ---- ---- -------
 Normal DeploymentRollback 54m deployment-controller Rolled back deployment "tomcat-deployment" to revision 5
 Normal ScalingReplicaSet 54m (x2 over 6d) deployment-controller Scaled up replica set tomcat-deployment-5cd68b69d to 1
 Normal ScalingReplicaSet 54m deployment-controller Scaled down replica set tomcat-deployment-799f9cc9 to 2
 Normal ScalingReplicaSet 54m (x2 over 6d) deployment-controller Scaled up replica set tomcat-deployment-5cd68b69d to 2
 Normal ScalingReplicaSet 54m (x2 over 6d) deployment-controller Scaled up replica set tomcat-deployment-5cd68b69d to 3
 Normal ScalingReplicaSet 54m deployment-controller Scaled down replica set tomcat-deployment-799f9cc9 to 1
 Normal ScalingReplicaSet 54m deployment-controller Scaled down replica set tomcat-deployment-799f9cc9 to 0
 Normal ScalingReplicaSet 18m (x2 over 1h) deployment-controller Scaled up replica set tomcat-deployment-799f9cc9 to 1
 Normal DeploymentRollback 18m deployment-controller Rolled back deployment "tomcat-deployment" to revision 6
 Normal ScalingReplicaSet 18m (x2 over 1h) deployment-controller Scaled up replica set tomcat-deployment-799f9cc9 to 2
 Normal ScalingReplicaSet 18m (x2 over 1h) deployment-controller Scaled down replica set tomcat-deployment-5cd68b69d to 2
 Normal ScalingReplicaSet 18m (x2 over 1h) deployment-controller Scaled down replica set tomcat-deployment-5cd68b69d to 1
 Normal ScalingReplicaSet 18m (x2 over 1h) deployment-controller Scaled up replica set tomcat-deployment-799f9cc9 to 3
 Normal ScalingReplicaSet 18m (x2 over 1h) deployment-controller Scaled down replica set tomcat-deployment-5cd68b69d to 0

可看到有DeploymentRollback  Reason的事件

 

扩展Deployment

可通过如下的命令进行扩展

[root@master yaml]# kubectl scale deployment tomcat-deployment --replicas=5
deployment "tomcat-deployment" scaled

查看Pods

[root@k4152v /data/yaml]# kubectl get pods
NAME READY STATUS RESTARTS AGE
tomcat-deployment-799f9cc9-9mmwv 1/1 Running 0 19m
tomcat-deployment-799f9cc9-hz2nv 1/1 Running 0 19m
tomcat-deployment-799f9cc9-mf4z2 1/1 Running 0 19m
tomcat-deployment-799f9cc9-hz2df 1/1 Running 0 3m
tomcat-deployment-799f9cc9-mf5t2 1/1 Running 0 3m

可见已扩展到5个

使用autoscale还可设置自动水平扩展（hpa），可根据机器负载之类的信息自动扩展或缩减，这个后面细讲

$ kubectl autoscale deployment tomcat-deployment --min=10 --max=15 --cpu-percent=80
deployment "tomcat-deployment" autoscaled

 

暂停和恢复Deployment

有时需要修改多个部分，而不是上面的只修改image，这样的话每次改完都自动部署，显然不好，通过pause即可暂停Deployment，更改完了，通过resume即可恢复部署

暂停

[root@master yaml]# kubectl rollout pause deployment/tomcat-deployment
deployment "tomcat-deployment" paused

修改

[root@master yaml]# kubectl set image deploy/tomcat-deployment nginx=10.209.3.81/library/appupdate2018418:v3
deployment "tomcat-deployment" image updated

查看Pods

[root@k4152v /data/yaml]# kubectl get pods
NAME READY STATUS RESTARTS AGE
tomcat-deployment-799f9cc9-9mmwv 1/1 Running 0 19m
tomcat-deployment-799f9cc9-hz2nv 1/1 Running 0 19m
tomcat-deployment-799f9cc9-mf4z2 1/1 Running 0 19m
tomcat-deployment-799f9cc9-hz2df 1/1 Running 0 3m
tomcat-deployment-799f9cc9-mf5t2 1/1 Running 0 3m

注意后面的AGE还是之前的Pod，这里就不会自动更新了

恢复

[root@master yaml]# kubectl rollout resume deploy/tomcat-deployment
deployment "tomcat-deployment" resumed

这时再查看Pods

[root@k4152v /data/yaml]# kubectl get pods
NAME READY STATUS RESTARTS AGE
tomcat-deployment-799f9cc9-9mmwv 1/1 Running 0 19m
tomcat-deployment-799f9cc9-hz2nv 1/1 Running 0 19m
tomcat-deployment-799f9cc9-mf4z2 1/1 Running 0 19m
tomcat-deployment-799f9cc9-hz2df 1/1 Running 0 3m
tomcat-deployment-799f9cc9-mf5t2 1/1 Running 0 3m

可见已经更新部署了

内部Deployment部分大概就讲完了，下面把nginx服务暴露到外面

删除Deployment

[root@master yaml]# kubectl delete -f tomcat-deployment.yaml 
deployment "tomcat-deployment" deleted

部署service

服务的暴露需要Service，它是Pod的抽象代理（具体机制见这里）。见nginx-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: tomcat-service
spec:
  type: NodePort
  sessionAffinity: ClientIP
  selector:
    app: tomcat
  ports:
    - port: 80
      nodePort: 32709
  • kind：Service代表是一个服务
  • type：NodePort k8s将会在每个Node上打开一个端口并且每个Node的端口都是一样的，通过<NodeIP>:NodePort的方式Kubernetes集群外部的程序可以访问Service。
  • selector：哪个服务需要暴露
  • port：service暴露的端口
  • TargetPort：pod的端口
  • nodePort：对外暴露的端口，不设置会默认分配，范围：30000－32767
  • 转发逻辑是：
    <NodeIP>:<nodeport> => <ServiceVIP>:<port>=> <PodIP>:<targetport>

部署service服务：

[root@master yaml]# kubectl create -f tomcat-service.yaml 
service "tomcat-service" created

可看到启动了一个svc

[root@k4152v /data/yaml]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
tomcat-service NodePort 10.102.246.240 <none> 8080:32097/TCP 6d

浏览器测试

由于没有在代理上安装docker，所有临时加了个node节点测试，把流量切过去后，就可以看到负载情况，如下图：

基于生成环境tomcat的Kubernetes的deployment使用

再看看日志：

基于生成环境tomcat的Kubernetes的deployment使用

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