Kubernetes Deployment控制器
Deployment 是 Kubernetes 中最常见的控制器，实际上它是一个两层控制器。
- 首先，它通过 ReplicaSet 的个数来描述应用的版本；
- 然后，它再通过 ReplicaSet 的属性（比如 replicas 的值），来保证 Pod 的副本数量。
注：Deployment 控制 ReplicaSet（版本），ReplicaSet 控制 Pod（副本数）。这个两层控制关系一定要牢记。
Deployment 是 Kubernetes 编排能力的一种提现，通过 Deployment 我们可以让 Pod 稳定的维持在指定的数量，除此之外还有滚动更新、版本回滚等功能。
Deployment
自愈能力
我们通过一个例子来演示来Deployment的自愈能力。
通过 kubectl run 来创建一个 mynginx Pod
[root@k8s-master ~]# kubectl run mynginx --image=nginx
pod/mynginx created通过 kubectl create deployment 来创建一个 mytomcat Pod
[root@k8s-master ~]# kubectl create deployment mytomcat --image=tomcat:8.5.68
deployment.apps/mytomcat created我们比较下这两种方式分别创建的 Pod 有什么不同？
首先把 kubectl run 修建的 mynginx Pod 删除了
[root@k8s-master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
mynginx 1/1 Running 0 94s
mytomcat-6f5f895f4f-b5ckr 1/1 Running 0 83s
[root@k8s-master ~]# kubectl delete pod mynginx
pod "mynginx" deleted
[root@k8s-master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
mytomcat-6f5f895f4f-b5ckr 1/1 Running 0 100s接着再删除 mytomcat Pod
[root@k8s-master ~]# kubectl delete pod mytomcat-6f5f895f4f-b5ckr
pod "mytomcat-6f5f895f4f-b5ckr" deleted再次查看 Pod
[root@k8s-master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
mytomcat-6f5f895f4f-j7w22 1/1 Running 0 17s总结：通过 Deployment 创建的 Pod，不怕机器宕机或应用崩溃，Deployment创建的Pod它有自愈能力
如果想要删除呢？那就是删除本次部署
# 查看 deployment
[root@k8s-master ~]# kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
mytomcat 1/1 1 # 删除 deployment
[root@k8s-master ~]# kubectl delete deploy mytomcat
deployment.apps "mytomcat" deleted[root@k8s-master ~]# kubectl get deploy
No resources found in default namespace.
[root@k8s-master ~]# kubectl get pod
No resources found in default namespace.多副本
命令行方式
[root@k8s-master ~]# kubectl create deployment my-nginx-deployment --image=nginx --replicas=3 deployment.apps/my-nginx-deployment created使用
--replicas表示本次部署起多少个 Pod[root@k8s-master ~]# kubectl get deploy NAME READY UP-TO-DATE AVAILABLE AGE my-nginx-deployment 3/3 3 3 17s[root@k8s-master ~]# kubectl get pod -owide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES my-nginx-deployment-799847ccc9-dx59g 1/1 Running 0 2m50s 192.168.36.70 k8s-node1 <none> <none> my-nginx-deployment-799847ccc9-mfhpz 1/1 Running 0 2m50s 192.168.169.133 k8s-node2 <none> <none> my-nginx-deployment-799847ccc9-xwlx4 1/1 Running 0 2m50s 192.168.36.71 k8s-node1 <none> <none>因为在我们有台node2机器，可以看到 my-nginx-deployment Pod 分散到两台机器上部署
配置文件方式
先删除命令行方式创建的
[root@k8s-master ~]# kubectl delete deploy my-nginx-deployment deployment.apps "my-nginx-deployment" deleted准备 my-nginx-deployment.yaml
apiVersion: apps/v1 kind: Deployment metadata: labels: app: my-nginx-deployment name: my-nginx-deployment spec: replicas: 3 selector: matchLabels: app: my-nginx-deployment template: metadata: labels: app: my-nginx-deployment spec: containers: - image: nginx name: nginx创建实例
[root@k8s-master ~]# kubectl apply -f deployment/my-nginx-deployment.yaml deployment.apps/my-nginx-deployment created查看
[root@k8s-master ~]# kubectl get deployment NAME READY UP-TO-DATE AVAILABLE AGE my-nginx-deployment 3/3 3 3 34s [root@k8s-master ~]# kubectl get pod NAME READY STATUS RESTARTS AGE my-nginx-deployment-799847ccc9-fj85l 1/1 Running 0 37s my-nginx-deployment-799847ccc9-n2xtn 1/1 Running 0 37s my-nginx-deployment-799847ccc9-tdtgx 1/1 Running 0 37s
扩缩容能力
首先我们部署 3 个实例的 Pod
[root@k8s-master ~]# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
my-nginx-deployment 3/3 3 3 20m
[root@k8s-master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
my-nginx-deployment-799847ccc9-fj85l 1/1 Running 0 20m
my-nginx-deployment-799847ccc9-n2xtn 1/1 Running 0 20m
my-nginx-deployment-799847ccc9-tdtgx 1/1 Running 0 20m命令行方式扩缩容
进行扩容， —replicas=5 表示扩容到5个Pod
[root@k8s-master ~]# kubectl scale --replicas=5 deployment/my-nginx-deployment deployment.apps/my-nginx-deployment scaled查看扩容后的Pod
[root@k8s-master ~]# kubectl get pod NAME READY STATUS RESTARTS AGE my-nginx-deployment-799847ccc9-blrss 1/1 Running 0 56s my-nginx-deployment-799847ccc9-fj85l 1/1 Running 0 23m my-nginx-deployment-799847ccc9-n2xtn 1/1 Running 0 23m my-nginx-deployment-799847ccc9-tdtgx 1/1 Running 0 23m my-nginx-deployment-799847ccc9-v96gh 1/1 Running 0 56s进行缩容
[root@k8s-master ~]# kubectl scale --replicas=3 deployment/my-nginx-deployment deployment.apps/my-nginx-deployment scaled查看缩容后的Pod
[root@k8s-master ~]# kubectl get pod NAME READY STATUS RESTARTS AGE my-nginx-deployment-799847ccc9-fj85l 1/1 Running 0 24m my-nginx-deployment-799847ccc9-n2xtn 1/1 Running 0 24m my-nginx-deployment-799847ccc9-tdtgx 1/1 Running 0 24m配置文件方式扩缩容
[root@k8s-master ~]# kubectl get deploy NAME READY UP-TO-DATE AVAILABLE AGE my-nginx-deployment 3/3 3 3 27m # 修改 replicas: 4 [root@k8s-master ~]# kubectl edit deployment my-nginx-deployment # 查看效果 [root@k8s-master ~]# kubectl get pod NAME READY STATUS RESTARTS AGE my-nginx-deployment-799847ccc9-fj85l 1/1 Running 0 28m my-nginx-deployment-799847ccc9-n2xtn 1/1 Running 0 28m my-nginx-deployment-799847ccc9-nzm8x 1/1 Running 0 23s my-nginx-deployment-799847ccc9-tdtgx 1/1 Running 0 28m
故障转移能力
下面我们来演示下自愈&故障转移能力
查看 pod
[root@k8s-master ~]# kubectl get pod -owide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
my-nginx-deployment-799847ccc9-fj85l 1/1 Running 0 40m 192.168.169.134 k8s-node2 <none> <none>
my-nginx-deployment-799847ccc9-n2xtn 1/1 Running 0 40m 192.168.36.73 k8s-node1 <none> <none>
my-nginx-deployment-799847ccc9-nzm8x 1/1 Running 0 11m 192.168.169.137 k8s-node2 <none> <none>
my-nginx-deployment-799847ccc9-tdtgx 1/1 Running 0 40m 192.168.36.72 k8s-node1 <none> <none>监控pod
[root@k8s-master ~]# watch -n 1 kubectl get pod
Every 1.0s: kubectl get pod Sun Aug 14 19:13:41 2022
NAME READY STATUS RESTARTS AGE
my-nginx-deployment-799847ccc9-fj85l 1/1 Running 0 41m
my-nginx-deployment-799847ccc9-n2xtn 1/1 Running 0 41m
my-nginx-deployment-799847ccc9-nzm8x 1/1 Running 0 13m
my-nginx-deployment-799847ccc9-tdtgx 1/1 Running 0 41m在 k8s-node1 节点上停止容器
[root@k8s-node1 ~]# docker ps | grep my-nginx
4da287650d27 nginx "/docker-entrypoint.…" 42 minutes ago Up 42 minutes k8s_nginx_my-nginx-deployment-799847ccc9-n2xtn_default_8feb6cd8-1c8e-41ba-8f85-d365fd1cb88c_0
16e18c7b9c0d nginx "/docker-entrypoint.…" 43 minutes ago Up 43 minutes k8s_nginx_my-nginx-deployment-799847ccc9-tdtgx_default_79e17be3-4d3c-4534-a1e0-efb03af8c282_0
1f201df2a201 registry.cn-hangzhou.aliyuncs.com/lfy_k8s_images/pause:3.2 "/pause" 43 minutes ago Up 43 minutes k8s_POD_my-nginx-deployment-799847ccc9-n2xtn_default_8feb6cd8-1c8e-41ba-8f85-d365fd1cb88c_0
16b0091c2ea6 registry.cn-hangzhou.aliyuncs.com/lfy_k8s_images/pause:3.2 "/pause" 43 minutes ago Up 43 minutes k8s_POD_my-nginx-deployment-799847ccc9-tdtgx_default_79e17be3-4d3c-4534-a1e0-
efb03af8c282_0
[root@k8s-node1 ~]# docker stop 4da287650d27
4da287650d27观察 pod 的变化
[root@k8s-master ~]# watch -n 1 kubectl get pod
Every 1.0s: kubectl get pod Sun Aug 14 19:16:38 2022
NAME READY STATUS RESTARTS AGE
my-nginx-deployment-799847ccc9-fj85l 1/1 Running 0 44m
my-nginx-deployment-799847ccc9-n2xtn 1/1 Running 1 44m
my-nginx-deployment-799847ccc9-nzm8x 1/1 Running 0 15m
my-nginx-deployment-799847ccc9-tdtgx 1/1 Running 0 44m 可以看到 my-nginx-deployment-799847ccc9-n2xtn Pod 重启了一次
故障转移，我们可以对 k8s-node1 节点机器关机，关机后观察 pod 变化
滚动更新
将一个集群中正在运行的多个 Pod 版本，交替地逐一升级的过程，就是“滚动更新”。
先将新版本的V2从0个扩容到1个Pod，接着将旧版本的V1 从3个缩容到2个，这样慢慢的最后V1缩为0个，V2扩到3个。
滚动更新好处就是，即使V2版本出现异常，此时也会有两个V1版本在运行，然后用户可以手动处理这种情况，比如停止更新或者回滚到V1版本
下面我们测试滚动更新
[root@k8s-master ~]# kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
my-nginx-deployment 3/3 3 3 56m
[root@k8s-master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
my-nginx-deployment-799847ccc9-fj85l 1/1 Running 0 56m
my-nginx-deployment-799847ccc9-n2xtn 1/1 Running 2 56m
my-nginx-deployment-799847ccc9-nzm8x 1/1 Running 0 28m命令行方式
[root@k8s-master ~]# kubectl set image deployment/my-nginx-deployment nginx=nginx:1.16.1 --record deployment.apps/my-nginx-deployment image updated # 观察变化 [root@k8s-master ~]# watch -n 1 kubectl get pod Every 1.0s: kubectl get pod Sun Aug 14 19:35:18 2022 NAME READY STATUS RESTARTS AGE my-nginx-deployment-69dfcd645b-vptn2 0/1 ContainerCreating 0 17s my-nginx-deployment-799847ccc9-fj85l 1/1 Running 0 63m my-nginx-deployment-799847ccc9-n2xtn 1/1 Running 2 63m my-nginx-deployment-799847ccc9-nzm8x 1/1 Running 0 34mset image 表示我们要改变镜像，改变哪个镜像？改变的是 deployment/my-nginx-deployment 这个deployment 中的 nginx 镜像，把它镜像变为 nginx:1.16.1版本，—record 表示记录下本次版本的更新
配置文件方式
# 修改 spec.template.spec.containers.image 值为 nginx:1.9.1 kubectl edit deployment/my-nginx-deployment
版本回退
首先，我需要使用 kubectl rollout history 命令，查看每次 Deployment 变更对应的版本
# 查看历史记录
[root@k8s-master ~]# kubectl rollout history deployment/my-nginx-deployment
deployment.apps/my-nginx-deployment
REVISION CHANGE-CAUSE
1 <none>
2 kubectl set image deployment/my-nginx-deployment nginx=nginx:1.16.1 --record=true
3 kubectl set image deployment/my-nginx-deployment nginx=nginx:1.16.1 --record=true
4 kubectl set image deployment/my-nginx-deployment nginx=nginx:1.16.1 --record=true
#查看某个历史详情
[root@k8s-master ~]# kubectl rollout history deployment/my-nginx-deployment --revision=2
deployment.apps/my-nginx-deployment with revision #2
Pod Template:
Labels: app=my-nginx-deployment
pod-template-hash=69dfcd645b
Annotations: kubernetes.io/change-cause: kubectl set image deployment/my-nginx-deployment nginx=nginx:1.16.1 --record=true
Containers:
nginx:
Image: nginx:1.16.1
Port: <none>
Host Port: <none>
Environment: <none>
Mounts: <none>
Volumes: <none>
[root@k8s-master ~]# kubectl rollout history deployment/my-nginx-deployment --revision=3
deployment.apps/my-nginx-deployment with revision #3
Pod Template:
Labels: app=my-nginx-deployment
pod-template-hash=dc798486d
Annotations: kubernetes.io/change-cause: kubectl set image deployment/my-nginx-deployment nginx=nginx:1.16.1 --record=true
Containers:
nginx:
Image: nginx:1.91
Port: <none>
Host Port: <none>
Environment: <none>
Mounts: <none>
Volumes: <none>
[root@k8s-master ~]# kubectl rollout history deployment/my-nginx-deployment --revision=4
deployment.apps/my-nginx-deployment with revision #4
Pod Template:
Labels: app=my-nginx-deployment
pod-template-hash=64f546978b
Annotations: kubernetes.io/change-cause: kubectl set image deployment/my-nginx-deployment nginx=nginx:1.16.1 --record=true
Containers:
nginx:
Image: nginx:1.9.1
Port: <none>
Host Port: <none>
Environment: <none>
Mounts: <none>
Volumes: <none>然后，我们就可以在 kubectl rollout undo 命令行最后，加上要回滚到的指定版本的版本号，就可以回滚到指定版本了。
#回滚(回到上次)
kubectl rollout undo deployment/my-nginx-deployment
#回滚(回到指定版本)
[root@k8s-master ~]# kubectl rollout undo deployment/my-nginx-deployment --to-revision=2
deployment.apps/my-nginx-deployment rolled back
#验证回退到了 1.16.1 版本
[root@k8s-master ~]# kubectl get deploy/my-nginx-deployment -oyaml | grep image
{"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"labels":{"app":"my-nginx-deployment"},"name":"my-nginx-deployment","namespace":"default"},"spec":{"replicas":3,"selector":{"matchLabels":{"app":"my-nginx-deployment"}},"template":{"metadata":{"labels":{"app":"my-nginx-deployment"}},"spec":{"containers":[{"image":"nginx","name":"nginx"}]}}}}
kubernetes.io/change-cause: kubectl set image deployment/my-nginx-deployment nginx=nginx:1.16.1
f:imagePullPolicy: {}
f:image: {}
- image: nginx:1.16.1
imagePullPolicy: Always