9.1 k8s pod版本更新流程及命令行实现升级与回滚

1.创建 Deployment

root@k8-deploy:~/k8s-yaml/controllers/deployments# vim nginx-deployment.yaml

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:1.14.2

        ports:

        - containerPort: 80

在该例中：

创建名为 nginx-deployment（由 .metadata.name 字段标明）的 Deployment。
该 Deployment 创建三个（由 replicas 字段标明）Pod 副本。
selector 字段定义 Deployment 如何查找要管理的 Pods。在这里，你选择在 Pod 模板中定义的标签（app: nginx）, 在 API 版本 apps/v1 中，Deployment 标签选择算符在创建后是不可变的。

说明：

spec.selector.matchLabels 字段是 {key,value} 键值对映射。在 matchLabels 映射中的每个 {key,value} 映射等效于 matchExpressions 中的一个元素，即其 key 字段是 “key”，operator 为 “In”，values 数组仅包含 “value”。在 matchLabels 和 matchExpressions 中给出的所有条件都必须满足才能匹配。

template 字段包含以下子字段：

Pod 被使用 labels 字段打上 app: nginx 标签。
Pod 模板规约（即 .template.spec 字段）指示 Pods 运行一个 nginx 容器，该容器运行版本为 1.14.2 的 nginx Docker Hub镜像。
创建一个容器并使用 name 字段将其命名为 nginx。

通过运行以下命令创建 Deployment

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl apply -f nginx-deployment.yaml

deployment.apps/nginx-deployment created

说明：你可以设置 --record 标志将所执行的命令写入资源注解中。这对于以后的检查是有用的。例如，要查看针对每个 Deployment 修订版本所执行过的命令。

检查 Deployment 是否已创建

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get deploy

NAME               READY   UP-TO-DATE   AVAILABLE   AGE

nginx-deployment   0/3     3            0           9s

在检查集群中的 Deployment 时，所显示的字段有：

NAME 列出了集群中 Deployment 的名称。
READY 显示应用程序的可用的副本数。显示的模式是“就绪个数/期望个数”。
UP-TO-DATE 显示为了达到期望状态已经更新的副本数。
AVAILABLE 显示应用可供用户使用的副本数。
AGE 显示应用程序运行的时间。
请注意期望副本数是根据 .spec.replicas 字段设置 3。

几秒钟后再次运行 kubectl get deployments

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get deploy

NAME               READY   UP-TO-DATE   AVAILABLE   AGE

nginx-deployment   3/3     3            3           45s

要查看 Deployment 创建的 ReplicaSet（rs）

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get rs

NAME                          DESIRED   CURRENT   READY   AGE

nginx-deployment-66b6c48dd5   3         3         3       11m

ReplicaSet 输出中包含以下字段：

NAME 列出名字空间中 ReplicaSet 的名称；

DESIRED 显示应用的期望副本个数，即在创建 Deployment 时所定义的值。此为期望状态；
CURRENT 显示当前运行状态中的副本个数；
READY 显示应用中有多少副本可以为用户提供服务；
AGE 显示应用已经运行的时间长度。
注意 ReplicaSet 的名称始终被格式化为[Deployment名称]-[随机字符串]。其中的随机字符串是使用 pod-template-hash 作为种子随机生成的。

查看每个 Pod 自动生成的标签

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get pods --show-labels

NAME                                READY   STATUS    RESTARTS   AGE   LABELS

nginx-deployment-66b6c48dd5-hdxlg   1/1     Running   0          44m   app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-hnmgw   1/1     Running   0          44m   app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-p28z2   1/1     Running   0          44m   app=nginx,pod-template-hash=66b6c48dd5

说明：

你必须在 Deployment 中指定适当的选择算符和 Pod 模板标签（在本例中为 app: nginx）。标签或者选择算符不要与其他控制器（包括其他 Deployment 和 StatefulSet）重叠。 Kubernetes 不会阻止你这样做，但是如果多个控制器具有重叠的选择算符，它们可能会发生冲突执行难以预料的操作。
Deployment 控制器将 pod-template-hash 标签添加到 Deployment 所创建或收留的每个 ReplicaSet 。

此标签可确保 Deployment 的子 ReplicaSets 不重叠。标签是通过对 ReplicaSet 的 PodTemplate 进行哈希处理。所生成的哈希值被添加到 ReplicaSet 选择算符、Pod 模板标签，并存在于在 ReplicaSet 可能拥有的任何现有 Pod 中。

2.更新 Deployment

说明：

仅当 Deployment Pod 模板（即 .spec.template）发生改变时，例如模板的标签或容器镜像被更新，才会触发 Deployment 上线。其他更新（如对 Deployment 执行扩缩容的操作）不会触发上线动作。

更新nginx Pod的镜像版本，比如从nginx:1.14.2升级到nginx:1.16.1

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record

deployment.apps/nginx-deployment image updated

监控更新过程

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl rollout status deployment/nginx-deployment

Waiting for deployment "nginx-deployment" rollout to finish: 2 out of 3 new replicas have been updated...

Waiting for deployment "nginx-deployment" rollout to finish: 2 out of 3 new replicas have been updated...

Waiting for deployment "nginx-deployment" rollout to finish: 2 out of 3 new replicas have been updated...

Waiting for deployment "nginx-deployment" rollout to finish: 1 old replicas are pending termination...

Waiting for deployment "nginx-deployment" rollout to finish: 1 old replicas are pending termination...

deployment "nginx-deployment" successfully rolled out

在上线成功后,查看deployment

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get deploy

NAME               READY   UP-TO-DATE   AVAILABLE   AGE

nginx-deployment   3/3     3            3           72m

查看 Deployment控制的ReplicaSet

可以看出Deployment通过创建新的 ReplicaSet 并将其扩容到 3 个副本并将旧 ReplicaSet 缩容到 0 个副本完成了 Pod 的更新操作

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get rs

NAME                          DESIRED   CURRENT   READY   AGE

nginx-deployment-559d658b74   3         3         3       5m

nginx-deployment-66b6c48dd5   0         0         0       74m

查看更新后的pod

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get pod --show-labels

NAME                                READY   STATUS    RESTARTS   AGE     LABELS

nginx-deployment-559d658b74-4npbn   1/1     Running   0          6m29s   app=nginx,pod-template-hash=559d658b74

nginx-deployment-559d658b74-4wqbp   1/1     Running   0          6m17s   app=nginx,pod-template-hash=559d658b74

nginx-deployment-559d658b74-9wrpj   1/1     Running   0          6m41s   app=nginx,pod-template-hash=559d658b74

说明：

Deployment 可确保在更新时仅关闭一定数量的 Pod。默认情况下，它确保至少所需 Pods 75% 处于运行状态（最大不可用比例为 25%）。
Deployment 还确保仅所创建 Pod 数量只可能比期望 Pods 数高一点点。默认情况下，它可确保启动的 Pod 个数比期望个数最多多出 25%（最大峰值 25%）。

获取 Deployment 的更多信息

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl describe deployments

Name:                   nginx-deployment

Namespace:              default

CreationTimestamp:      Wed, 29 Sep 2021 16:01:55 +0800

Labels:                 app=nginx

Annotations:            deployment.kubernetes.io/revision: 2

                        kubernetes.io/change-cause: kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record=true

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:1.16.1

    Port:         80/TCP

    Host Port:    0/TCP

    Environment:  <none>

    Mounts:       <none>

  Volumes:        <none>

Conditions:

  Type           Status  Reason

  ----           ------  ------

  Available      True    MinimumReplicasAvailable

  Progressing    True    NewReplicaSetAvailable

OldReplicaSets:  <none>

NewReplicaSet:   nginx-deployment-559d658b74 (3/3 replicas created)

Events:

  Type    Reason             Age    From                   Message

  ----    ------             ----   ----                   -------

  Normal  ScalingReplicaSet  9m11s  deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 1

  Normal  ScalingReplicaSet  8m59s  deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 2

  Normal  ScalingReplicaSet  8m59s  deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 2

  Normal  ScalingReplicaSet  8m47s  deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 1

  Normal  ScalingReplicaSet  8m47s  deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 3

  Normal  ScalingReplicaSet  8m25s  deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 0

3.回滚 Deployment

说明：

Deployment 被触发上线时，系统就会创建 Deployment 的新的修订版本。这意味着仅当 Deployment 的 Pod 模板（.spec.template）发生更改时，才会创建新修订版本 -- 例如，模板的标签或容器镜像发生变化。其他更新，如 Deployment 的扩缩容操作不会创建 Deployment 修订版本。这是为了方便同时执行手动缩放或自动缩放。换言之，当你回滚到较早的修订版本时，只有 Deployment 的 Pod 模板部分会被回滚。

查看更新的历史记录

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl rollout history deployment.v1.apps/nginx-deployment

deployment.apps/nginx-deployment

REVISION  CHANGE-CAUSE

1         <none>

2         kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record=true

查看某个版本的更详细的更加记录信息

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl rollout history deployment.v1.apps/nginx-deployment --revision=2

deployment.apps/nginx-deployment with revision #2

Pod Template:

  Labels:       app=nginx

        pod-template-hash=559d658b74

  Annotations:  kubernetes.io/change-cause: kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record=true

  Containers:

   nginx:

    Image:      nginx:1.16.1

    Port:       80/TCP

    Host Port:  0/TCP

    Environment:        <none>

    Mounts:     <none>

  Volumes:      <none>

回滚到之前的版本

kubectl rollout undo deployment.v1.apps/nginx-deployment --to-revision=1

deployment.apps/nginx-deployment rolled back

查看回滚后的deployment

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get deployment nginx-deployment

NAME               READY   UP-TO-DATE   AVAILABLE   AGE

nginx-deployment   3/3     3            3           91m

查看deploymne的详细信息

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl describe deployment nginx-deployment

Name:                   nginx-deployment

Namespace:              default

CreationTimestamp:      Wed, 29 Sep 2021 16:01:55 +0800

Labels:                 app=nginx

Annotations:            deployment.kubernetes.io/revision: 3

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:1.14.2

    Port:         80/TCP

    Host Port:    0/TCP

    Environment:  <none>

    Mounts:       <none>

  Volumes:        <none>

Conditions:

  Type           Status  Reason

  ----           ------  ------

  Available      True    MinimumReplicasAvailable

  Progressing    True    NewReplicaSetAvailable

OldReplicaSets:  <none>

NewReplicaSet:   nginx-deployment-66b6c48dd5 (3/3 replicas created)

Events:

  Type    Reason             Age                From                   Message

  ----    ------             ----               ----                   -------

  Normal  ScalingReplicaSet  22m                deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 1

  Normal  ScalingReplicaSet  22m                deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 2

  Normal  ScalingReplicaSet  22m                deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 2

  Normal  ScalingReplicaSet  21m                deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 1

  Normal  ScalingReplicaSet  21m                deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 3

  Normal  ScalingReplicaSet  21m                deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 0

  Normal  ScalingReplicaSet  17s                deployment-controller  Scaled up replica set nginx-deployment-66b6c48dd5 to 1

  Normal  ScalingReplicaSet  15s                deployment-controller  Scaled down replica set nginx-deployment-559d658b74 to 2

  Normal  ScalingReplicaSet  15s                deployment-controller  Scaled up replica set nginx-deployment-66b6c48dd5 to 2

  Normal  ScalingReplicaSet  13s (x2 over 91m)  deployment-controller  Scaled up replica set nginx-deployment-66b6c48dd5 to 3

  Normal  ScalingReplicaSet  13s                deployment-controller  Scaled down replica set nginx-deployment-559d658b74 to 1

  Normal  ScalingReplicaSet  11s                deployment-controller  Scaled down replica set nginx-deployment-559d658b74 to 0

4.扩缩容Deployment

root@k8-deploy:~# kubectl scale deployment.v1.apps/nginx-deployment --replicas=10

deployment.apps/nginx-deployment scaled

root@k8-deploy:~# kubectl get deploy

NAME               READY   UP-TO-DATE   AVAILABLE   AGE

nginx-deployment   10/10   10           10          97m

root@k8-deploy:~# kubectl get rs

NAME                          DESIRED   CURRENT   READY   AGE

nginx-deployment-559d658b74   0         0         0       27m

nginx-deployment-66b6c48dd5   10        10        10      97m

root@k8-deploy:~# kubectl get pod -o wide --show-labels

NAME                                READY   STATUS    RESTARTS   AGE     IP               NODE           NOMINATED NODE   READINESS GATES   LABELS

nginx-deployment-66b6c48dd5-7tl82   1/1     Running   0          6m33s   10.100.112.5     192.168.2.19   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-b8wvd   1/1     Running   0          69s     10.100.172.196   192.168.2.17   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-cqmzm   1/1     Running   0          6m31s   10.100.112.6     192.168.2.19   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-h9bhf   1/1     Running   0          69s     10.100.224.71    192.168.2.18   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-jzhkt   1/1     Running   0          69s     10.100.224.72    192.168.2.18   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-kdvss   1/1     Running   0          6m29s   10.100.112.7     192.168.2.19   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-kxsvq   1/1     Running   0          69s     10.100.172.197   192.168.2.17   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-tlckf   1/1     Running   0          69s     10.100.112.8     192.168.2.19   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-wfvmh   1/1     Running   0          69s     10.100.224.73    192.168.2.18   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

nginx-deployment-66b6c48dd5-zmsfm   1/1     Running   0          69s     10.100.112.9     192.168.2.19   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

暂停、恢复 Deployment

你可以在触发一个或多个更新之前暂停 Deployment，然后再恢复其执行。

这样做使得你能够在暂停和恢复执行之间应用多个修补程序，而不会触发不必要的上线操作。

查看现有的deplymnet集群 rs

root@k8-deploy:~# kubectl get deployment

NAME               READY   UP-TO-DATE   AVAILABLE   AGE

nginx-deployment   3/3     3            3           4s

root@k8-deploy:~# kubectl get rs

NAME                          DESIRED   CURRENT   READY   AGE

nginx-deployment-66b6c48dd5   3         3         3       7s

执行暂停

root@k8-deploy:~# kubectl rollout pause deployment.v1.apps/nginx-deployment

deployment.apps/nginx-deployment paused

对deploymnet执行多项修改中的一项，比如修改pod镜像版本

root@k8-deploy:~# kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.17.10

deployment.apps/nginx-deployment image updated

在暂停期间对deploymnet的修改不会立即触发更新

root@k8-deploy:~# kubectl rollout history deployment.v1.apps/nginx-deployment

deployment.apps/nginx-deployment

REVISION  CHANGE-CAUSE

1         <none>

继续对deploymnet镜像修改，比如对pod使用的资源进行限制

root@k8-deploy:~# kubectl set resources deployment.v1.apps/nginx-deployment -c=nginx --limits=cpu=200m,memory=512Mi

deployment.apps/nginx-deployment resource requirements updated

# 此时deployment仍然不会触发更新

root@k8-deploy:~# kubectl rollout history deployment.v1.apps/nginx-deployment

deployment.apps/nginx-deployment

REVISION  CHANGE-CAUSE

1         <none

恢复 Deployment 执行

root@k8-deploy:~# kubectl rollout resume deployment.v1.apps/nginx-deployment

deployment.apps/nginx-deployment resumed

观察新的 ReplicaSet 的创建过程，其中包含了所应用的所有更新

root@k8-deploy:~# kubectl get rs -w

NAME                          DESIRED   CURRENT   READY   AGE

nginx-deployment-66b6c48dd5   2         2         2       6m26s

nginx-deployment-fcfbff66c    2         2         1       6s

nginx-deployment-fcfbff66c    2         2         2       16s

nginx-deployment-66b6c48dd5   1         2         2       6m36s

nginx-deployment-fcfbff66c    3         2         2       16s

nginx-deployment-66b6c48dd5   1         2         2       6m36s

nginx-deployment-fcfbff66c    3         2         2       16s

nginx-deployment-fcfbff66c    3         3         2       16s

nginx-deployment-66b6c48dd5   1         1         1       6m36s

nginx-deployment-fcfbff66c    3         3         3       28s

nginx-deployment-66b6c48dd5   0         1         1       6m48s

nginx-deployment-66b6c48dd5   0         1         1       6m48s

nginx-deployment-66b6c48dd5   0         0         0       6m48s

root@k8-deploy:~# kubectl get rs

NAME                          DESIRED   CURRENT   READY   AGE

nginx-deployment-66b6c48dd5   0         0         0       7m55s

nginx-deployment-fcfbff66c    3         3         3       95s

root@k8-deploy:~# kubectl rollout history deployment.v1.apps/nginx-deployment

deployment.apps/nginx-deployment

REVISION  CHANGE-CAUSE

1         <none>

2         <none>