k8s 使用篇 - deployment
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，因此后面也不会起文章单独讨论ReplicationController了。node
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，以避免发生冲突。nginx
建立Deployment
以下一个Deployment的配置（nginx-deployment.yaml），建立一个ReplicaSet包含3个nginx Podsdocker
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 80
- apiVersion这里为apps/v1，若是是1.9以前的版本为extensions/v1beta1
- replicas:3 起3个replicated Pods
- selector指明哪一个pod被管理，这里咱们指定了label（app:nginx）
- template: spec 指明了运行一个容器nginx（以nginx:1.7.9为镜像）
- 开放80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 时不要和其余的重复，k8s不会检查这个，须要人工本身确认api
要建立此部署，执行下面的命令（在这以前咱们提早下好nginx相关的镜像，docker pull nginx:1.7.9）浏览器
[root@master yaml]# kubectl create -f nginx-deployment.yaml --record deployment "nginx-deployment" created
- --record会记录操做历史，以便于后面回滚操做
查看deploymentsbash
[root@master yaml]# kubectl get deployments NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE nginx-deployment 3 0 0 0 1s
- 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
经过下面语句可查追踪部署状况session
[root@master ~]# kubectl rollout status deployment/nginx-deployment deployment "nginx-deployment" successfully rolled out # 这是部署完成的状态 # 未完成的会显示当前部署哪一步了 [root@master ~]# kubectl rollout status deployment/nginx-deployment Waiting for rollout to finish: 2 out of 3 new replicas have been updated... deployment "nginx-deployment" successfully rolled out
过一会咱们再查看，就全app
[root@master ~]# kubectl get deployments NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE nginx-deployment 3 3 3 3 51s
这里注意若是定义了.spec.minReadySeconds，那么必须通过定义的时间才会达到AVAILABLE 状态编辑器
经过下面的命令查看Deployment建立的ReplicaSet（rs）ide
[root@master ~]# kubectl get rs NAME DESIRED CURRENT READY AGE nginx-deployment-6c54bd5869 3 3 3 56m
注意ReplicaSet的名称格式为[DEPLOYMENT-NAME]-[POD-TEMPLATE-HASH-VALUE]，后面的hash值是由Deployment自动建立的
查看Pods
[root@master ~]# kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS nginx-deployment-6c54bd5869-9brqp 1/1 Running 0 58m app=nginx,pod-template-hash=2710681425 nginx-deployment-6c54bd5869-dkmgh 1/1 Running 0 58m app=nginx,pod-template-hash=2710681425 nginx-deployment-6c54bd5869-vzsht 1/1 Running 0 58m app=nginx,pod-template-hash=2710681425
建立的ReplicaSet 会确保时刻有3个nginx Pods的副本在运行
更新Deployment
假设咱们想把nginx从1.7.9更新到1.9.1，有如下3种方式
1. 直接set命令设置变动的部分
$ kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1 deployment "nginx-deployment" image updated
以上命令会自动回滚更改Pods，即中止必定量的老的，新建新的，直到来的终止完，新的启动完
经过describe便可查看全部的细节
[root@master yaml]# kubectl describe deployment/nginx-deployment
Name: nginx-deployment
Namespace: default
CreationTimestamp: Thu, 15 Mar 2018 02:51:06 -0400
Labels: app=nginx
Annotations: deployment.kubernetes.io/revision=2
kubernetes.io/change-cause=kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1
Selector: app=nginx
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=nginx
Containers:
nginx:
Image: nginx:1.9.1
Port: 80/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets: <none>
NewReplicaSet: nginx-deployment-5964dfd755 (3/3 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 2m deployment-controller Scaled up replica set nginx-deployment-5964dfd755 to 1
Normal ScalingReplicaSet 2m deployment-controller Scaled down replica set nginx-deployment-6c54bd5869 to 2
Normal ScalingReplicaSet 2m deployment-controller Scaled up replica set nginx-deployment-5964dfd755 to 2
Normal ScalingReplicaSet 2m deployment-controller Scaled down replica set nginx-deployment-6c54bd5869 to 1
Normal ScalingReplicaSet 2m deployment-controller Scaled up replica set nginx-deployment-5964dfd755 to 3
Normal ScalingReplicaSet 2m deployment-controller Scaled down replica set nginx-deployment-6c54bd5869 to 0
- 可见image已经变了
- 另外Events可查看滚动更新的过程
- 另外上面的说的中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确保建立新的pod也在必定比例上（这里默认也是25%）
2. 经过直接修改线上的配置也可直接修改
kubectl edit deployment/nginx-deployment
会打开一个编辑器，修改指定的部分便可，这里是.spec.template.spec.containers[0].image
3. 修改yaml文件，经过apply从新部署
[root@master yaml]# kubectl apply -f nginx-deployment.yaml Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply deployment "nginx-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参数建立的 或 由apply建立的 （apply当资源不存在时会建立）
这时咱们查看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@master yaml]# kubectl get rs NAME DESIRED CURRENT READY AGE nginx-deployment-5964dfd755 3 3 3 21m nginx-deployment-6c54bd5869 0 0 0 1h
回滚Deployment
有时须要回滚的操做，好比更新错误，手误等一系列问题
好比上面的操做更新到1.9.1时，写错了，写成1.91了
[root@master yaml]# kubectl set image deployment/nginx-deployment nginx=nginx:1.91 deployment "nginx-deployment" image updated
追踪状态
[root@master yaml]# kubectl rollout status deployments nginx-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以下
[root@master yaml]# kubectl get rs NAME DESIRED CURRENT READY AGE nginx-deployment-5964dfd755 3 3 3 40m nginx-deployment-5d5cfdbd5f 1 1 0 1m nginx-deployment-6c54bd5869 0 0 0 2h
新的rs只启动了Pod但没有处于READY状态
查看Pods
[root@master yaml]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx-deployment-5964dfd755-8z8b7 1/1 Running 0 27m nginx-deployment-5964dfd755-bnznj 1/1 Running 0 27m nginx-deployment-5964dfd755-pt54q 1/1 Running 0 27m nginx-deployment-5d5cfdbd5f-srdcc 0/1 ImagePullBackOff 0 2m
可发现ImagePullBackOff，实际就是镜像不存在
要修复这个，咱们就须要rollback到前一个ok的版本
查看操做历史
[root@master yaml]# kubectl rollout history deployment/nginx-deployment deployments "nginx-deployment" REVISION CHANGE-CAUSE 1 kubectl create -f docs/user-guide/nginx-deployment.yaml --record 2 kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1 3 kubectl set image deployment/nginx-deployment nginx=nginx:1.91
要查看每一个版本的详细状况，指定--revision
[root@master yaml]# kubectl rollout history deployment/nginx-deployment --revision=2
deployments "nginx-deployment" with revision #2
Pod Template:
Labels: app=nginx
pod-template-hash=2710681425
Annotations: kubernetes.io/change-cause=kubectl edit deployment/nginx-deployment
Containers:
nginx:
Image: nginx:1.9.1
Port: 80/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
接下来进行回滚的操做
不指定版本，默认回滚到上一个版本
[root@master yaml]# kubectl rollout undo deployment/nginx-deployment deployment "nginx-deployment" rolled back
指定版本，经过--to-revision指定
[root@master yaml]# kubectl rollout undo deployment/nginx-deployment --to-revision=2 deployment "nginx-deployment" rolled back
查看
kubectl describe deployment/nginx-deployment
....略
Events:
FirstSeen LastSeen Count From SubobjectPath Type Reason Message
--------- -------- ----- ---- ------------- -------- ------ -------
30m 30m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-2035384211 to 3
29m 29m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-1564180365 to 1
29m 29m 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set nginx-deployment-2035384211 to 2
29m 29m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-1564180365 to 2
29m 29m 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set nginx-deployment-2035384211 to 0
29m 29m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-3066724191 to 2
29m 29m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-3066724191 to 1
29m 29m 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set nginx-deployment-1564180365 to 2
2m 2m 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set nginx-deployment-3066724191 to 0
2m 2m 1 {deployment-controller } Normal DeploymentRollback Rolled back deployment "nginx-deployment" to revision 2
29m 2m 2 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-1564180365 to 3
可看到有DeploymentRollback Reason的事件
扩展Deployment
可经过以下的命令进行扩展
[root@master yaml]# kubectl scale deployment nginx-deployment --replicas=5 deployment "nginx-deployment" scaled
查看Pods
[root@master yaml]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx-deployment-5964dfd755-8z8b7 1/1 Running 0 41m nginx-deployment-5964dfd755-bhm2s 1/1 Running 0 1m nginx-deployment-5964dfd755-bnznj 1/1 Running 0 41m nginx-deployment-5964dfd755-cftfj 1/1 Running 0 6s nginx-deployment-5964dfd755-pt54q 1/1 Running 0 41m
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 nginx-deployment --min=10 --max=15 --cpu-percent=80 deployment "nginx-deployment" autoscaled
暂停和恢复Deployment
有时须要修改多个部分，而不是上面的只修改image，这样的话每次改完都自动部署，显然很差，经过pause便可暂停Deployment，更改完了，经过resume便可恢复部署
暂停
[root@master yaml]# kubectl rollout pause deployment/nginx-deployment deployment "nginx-deployment" paused
修改
[root@master yaml]# kubectl set image deploy/nginx-deployment nginx=nginx:1.7.9 deployment "nginx-deployment" image updated
查看Pods
[root@master yaml]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx-deployment-5964dfd755-8z8b7 1/1 Running 0 57m nginx-deployment-5964dfd755-bhm2s 1/1 Running 0 17m nginx-deployment-5964dfd755-bnznj 1/1 Running 0 57m nginx-deployment-5964dfd755-cftfj 1/1 Running 0 16m nginx-deployment-5964dfd755-pt54q 1/1 Running 0 57m
注意后面的AGE仍是以前的Pod，这里就不会自动更新了
恢复
[root@master yaml]# kubectl rollout resume deploy/nginx-deployment deployment "nginx-deployment" resumed
这时再查看Pods
[root@master yaml]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx-deployment-6c54bd5869-htjxz 1/1 Running 0 25s nginx-deployment-6c54bd5869-lj288 1/1 Running 0 30s nginx-deployment-6c54bd5869-nt8lt 1/1 Running 0 30s nginx-deployment-6c54bd5869-svqz6 1/1 Running 0 29s nginx-deployment-6c54bd5869-zq8tl 1/1 Running 0 25s
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 nginx-deployment.yaml deployment "nginx-deployment" deleted
部署service
服务的暴露须要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: nginx-service
spec:
type: NodePort
sessionAffinity: ClientIP
selector:
app: nginx
ports:
- port: 80
nodePort: 30080
- kind：Service表明是一个服务
- type：NodePort k8s将会在每一个Node上打开一个端口而且每一个Node的端口都是同样的，经过<NodeIP>:NodePort的方式Kubernetes集群外部的程序能够访问Service。
- selector：哪一个服务须要暴露
- 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 nginx-service.yaml service "nginx-service" created
可看到启动了一个svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE svc/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 1d svc/nginx-service NodePort 10.101.86.235 <none> 80:30080/TCP 4m
浏览器测试
over！
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