作用

每个 Deployment 管理一组相同的应用 Pod（相同的一个副本）

image-20210711201124489

实践

YAML 文件

nginx-deployment
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apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3 # 期望的 Pod 数量
  selector:   # Pod Selector
    matchLabels:
      app: nginx
  template:   # Pod Template
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.7.9
          ports:
          - containerPort: 80

查看 Deployment

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$ kubectl get deployment
No resources found.

$ kubectl apply -f nginx-deployment.yaml
deployment.apps/nginx-deployment created

$ kubectl get deployment
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3/3     3            3           31s
READY UP-TO-DATE AVAILABLE
就绪 到达期望版本 运行中 + 可用

查看 Pod

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$ kubectl get pod
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-5754944d6c-7hkj9   1/1     Running   0          3m9s
nginx-deployment-5754944d6c-p2dr9   1/1     Running   0          3m9s
nginx-deployment-5754944d6c-ptr42   1/1     Running   0          3m9s

5754944d6c 为 pod-template-hash，Pod 的 OwnerReference 为 ReplicaSet（对应 Pod Template）

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kubectl get pod nginx-deployment-5754944d6c-7hkj9 -o yaml | head -n 17
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: "2021-07-11T12:26:59Z"
  generateName: nginx-deployment-5754944d6c-
  labels:
    app: nginx
    pod-template-hash: 5754944d6c
  name: nginx-deployment-5754944d6c-7hkj9
  namespace: default
  ownerReferences:
  - apiVersion: apps/v1
    blockOwnerDeletion: true
    controller: true
    kind: ReplicaSet
    name: nginx-deployment-5754944d6c
    uid: fe276bb5-8875-4c7d-b1b5-c07a98a84e16

更新镜像

deployment.v1.apps=资源名.资源版本.资源组，nginx=container.name

image-20210711203620459

pod-template-hash：5754944d6c -> 7448597cd5 -> 67fdfdb884

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$ kubectl set image deployment nginx-deployment nginx='nginx:1.9.1'
deployment.extensions/nginx-deployment image updated

$ kubectl get deployment nginx-deployment -o yaml
...
spec:
    ...
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx:1.9.1
...

$ kubectl get deployment
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3/3     3            3           19m

$ kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-5754944d6c   0         0         0       19m
nginx-deployment-7448597cd5   3         3         3       6m2s

$ kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-7448597cd5-4g9f9   1/1     Running   0          5m43s
nginx-deployment-7448597cd5-khvhx   1/1     Running   0          6m6s
nginx-deployment-7448597cd5-pvt98   1/1     Running   0          5m44s

$ kubectl set image deployment nginx-deployment nginx='nginx:1.9.2'
deployment.extensions/nginx-deployment image updated

$ kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-5754944d6c   0         0         0       23m
nginx-deployment-67fdfdb884   3         3         3       73s
nginx-deployment-7448597cd5   0         0         0       9m37s

$ kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-67fdfdb884-2mgkf   1/1     Running   0          48s
nginx-deployment-67fdfdb884-pjppp   1/1     Running   0          95s
nginx-deployment-67fdfdb884-z2fqt   1/1     Running   0          49s

版本回滚

查看版本

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$ kubectl rollout history deployment nginx-deployment
deployment.extensions/nginx-deployment
REVISION  CHANGE-CAUSE
1         <none>
2         <none>
3         <none>
1 2 3
nginx:1.7.9 nginx:1.9.1 nginx:1.9.2

回滚到上一版本（revision=2）

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$ kubectl rollout undo deployment nginx-deployment
deployment.extensions/nginx-deployment rolled back

$ kubectl rollout history deployment nginx-deployment
deployment.extensions/nginx-deployment
REVISION  CHANGE-CAUSE
1         <none>
3         <none>
4         <none>

$ kubectl get deployment nginx-deployment -o yaml
...
      - image: nginx:1.9.1
...
1 3 4
nginx:1.7.9 nginx:1.9.2 nginx:1.9.1

回滚到特定版本（revision=3）

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$ kubectl rollout undo deployment nginx-deployment --to-revision=3
deployment.extensions/nginx-deployment rolled back

$ kubectl get deployment nginx-deployment -o yaml
...
      - image: nginx:1.9.2
...

$ kubectl rollout history deployment nginx-deployment
deployment.extensions/nginx-deployment
REVISION  CHANGE-CAUSE
1         <none>
4         <none>
5         <none>
1 4 5
nginx:1.7.9 nginx:1.9.1 nginx:1.9.2

删除 Deployment

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$ kubectl delete -f nginx-deployment.yaml
deployment.apps "nginx-deployment" deleted

$ kubectl get deployment
No resources found.

Deployme Status

Processing：Deployment 正在扩容或者发布

image-20210711210022275

查看 Node

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$ kubectl get nodes
NAME       STATUS   ROLES    AGE   VERSION
minikube   Ready    master   56m   v1.15.5

创建 Deployment

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$ kubectl apply -f nginx-deployment.yaml
deployment.apps/nginx-deployment created

$ kubectl get deployment nginx-deployment
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3/3     3            3           20s

$ kubectl get pod
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-5754944d6c-c7j2k   1/1     Running   0          28s
nginx-deployment-5754944d6c-j6dwk   1/1     Running   0          28s
nginx-deployment-5754944d6c-ptmbz   1/1     Running   0          28s

spec.replicas = availableReplicas = readyReplicas = updatedReplicas = 3

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$ kubectl get deployment nginx-deployment -o yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "1"
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"labels":{"app":"nginx"},"name":"nginx-deployment","namespace":"default"},"spec":{"replicas":3,"selector":{"matchLabels":{"app":"nginx"}},"template":{"metadata":{"labels":{"app":"nginx"}},"spec":{"containers":[{"image":"nginx:1.7.9","name":"nginx","ports":[{"containerPort":80}]}]}}}}
  creationTimestamp: "2021-07-11T13:06:47Z"
  generation: 1
  labels:
    app: nginx
  name: nginx-deployment
  namespace: default
  resourceVersion: "3370"
  selfLink: /apis/extensions/v1beta1/namespaces/default/deployments/nginx-deployment
  uid: 3a4bbf35-df24-4be0-b91a-0c947d1f2f7e
spec:
  progressDeadlineSeconds: 600
  replicas: 3
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: nginx
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx:1.7.9
        imagePullPolicy: IfNotPresent
        name: nginx
        ports:
        - containerPort: 80
          protocol: TCP
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
status:
  availableReplicas: 3
  conditions:
  - lastTransitionTime: "2021-07-11T13:06:49Z"
    lastUpdateTime: "2021-07-11T13:06:49Z"
    message: Deployment has minimum availability.
    reason: MinimumReplicasAvailable
    status: "True"
    type: Available
  - lastTransitionTime: "2021-07-11T13:06:47Z"
    lastUpdateTime: "2021-07-11T13:06:49Z"
    message: ReplicaSet "nginx-deployment-5754944d6c" has successfully progressed.
    reason: NewReplicaSetAvailable
    status: "True"
    type: Progressing
  observedGeneration: 1
  readyReplicas: 3
  replicas: 3
  updatedReplicas: 3

查看 Pod

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$ kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-5754944d6c-c7j2k   1/1     Running   0          5m48s
nginx-deployment-5754944d6c-j6dwk   1/1     Running   0          5m48s
nginx-deployment-5754944d6c-ptmbz   1/1     Running   0          5m48s
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$ kubectl get pod nginx-deployment-5754944d6c-c7j2k -o yaml
...
  ownerReferences:
  - apiVersion: apps/v1
    blockOwnerDeletion: true
    controller: true
    kind: ReplicaSet
    name: nginx-deployment-5754944d6c
    uid: 9789dd3a-ee79-4488-bb2f-d9539909bbca
...
spec:
  containers:
  - image: nginx:1.7.9
...
status:
  conditions:
  - lastProbeTime: null
    lastTransitionTime: "2021-07-11T13:06:47Z"
    status: "True"
    type: Initialized
  - lastProbeTime: null
    lastTransitionTime: "2021-07-11T13:06:49Z"
    status: "True"
    type: Ready
  - lastProbeTime: null
    lastTransitionTime: "2021-07-11T13:06:49Z"
    status: "True"
    type: ContainersReady
  - lastProbeTime: null
    lastTransitionTime: "2021-07-11T13:06:47Z"
    status: "True"
    type: PodScheduled
...

更新升级

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$ kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-5754944d6c   3         3         3       9m22s

$ kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-5754944d6c-c7j2k   1/1     Running   0          9m59s
nginx-deployment-5754944d6c-j6dwk   1/1     Running   0          9m59s
nginx-deployment-5754944d6c-ptmbz   1/1     Running   0          9m59s

$ kubectl set image deployment nginx-deployment nginx='nginx:1.9.1'
deployment.extensions/nginx-deployment image updated

$ kubectl get pods
NAME                                READY   STATUS        RESTARTS   AGE
nginx-deployment-5754944d6c-c7j2k   1/1     Terminating   0          10m
nginx-deployment-5754944d6c-j6dwk   1/1     Running       0          10m
nginx-deployment-5754944d6c-ptmbz   1/1     Running       0          10m
nginx-deployment-7448597cd5-gzq4j   0/1     Pending       0          0s
nginx-deployment-7448597cd5-qbhr4   1/1     Running       0          2s

$ kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-5754944d6c   0         0         0       10m
nginx-deployment-7448597cd5   3         3         3       12s

$ kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-7448597cd5-7jlvf   1/1     Running   0          60s
nginx-deployment-7448597cd5-gzq4j   1/1     Running   0          61s
nginx-deployment-7448597cd5-qbhr4   1/1     Running   0          63s

$ kubectl get pod nginx-deployment-7448597cd5-7jlvf  -o yaml
...
spec:
  containers:
  - image: nginx:1.9.1
    imagePullPolicy: IfNotPresent
    name: nginx
...

revisionHistoryLimit

revisionHistoryLimit：保留历史版本的 ReplicaSet 的数量

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$ kubectl get deployment nginx-deployment  -o yaml
...
spec:
  progressDeadlineSeconds: 600
  replicas: 3
  revisionHistoryLimit: 10
...

$ kubectl set image deployment nginx-deployment nginx='nginx:1.9.2'
deployment.extensions/nginx-deployment image updated

$ kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-5754944d6c   0         0         0       16m
nginx-deployment-67fdfdb884   3         3         3       15s
nginx-deployment-7448597cd5   0         0         0       5m27s

将revisionHistoryLimit修改为1，只保留了1个历史版本（7448597cd5），而删除其余历史版本（5754944d6c）

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$ kubectl edit deployment nginx-deployment
deployment.extensions/nginx-deployment edited

$ kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-67fdfdb884   3         3         3       103s
nginx-deployment-7448597cd5   0         0         0       6m55s

架构设计

管理模式

image-20210711212642987

Deployment Controller

  1. Deployment Controller关注 Deployment 和 ReplicaSet 的 Event
  2. 判断 Check Paused：Paused=true，表示该 Deployment 不需要新的发布，只需要做数量上的维持
    • Yes
      • Sync replicas：同步到对应的ReplicaSet
      • Update status：更新 Deployment Status
    • No
      • Create/Update/Delete ReplicaSet

image-20210711212748506

ReplicaSet Controller

  1. 当 Deployment 分配 ReplicaSet 之后，ReplicaSet Controller会关注 ReplicaSet 和 Pod 的 Event
  2. ReplicaSet Controller：只管理副本数量，进行扩容或者缩容

image-20210711213553462

场景

扩容

image-20210711214027978

发布

image-20210711214121161

回滚

image-20210711220514050

字段解析

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$ kubectl get deployment nginx-deployment  -o yaml
...
spec:
  progressDeadlineSeconds: 600
  replicas: 3
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: nginx
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
...
Key Value
MinReadySeconds 判断 Pod 为 Available 的最小 Ready 时间
revisionHistoryLimit 保留历史ReplicaSet的数量
paused 标识，Deployment 只做数量维持，不做新的发布
progressDeadlineSeconds Deployment 长时间处于 Processing 状态会被进入 Fail 状态
maxUnavailable 滚动过程中最多有多少个 Pod 不可用
maxSurge 滚动过程中最多存在多少个 Pod 超过预期 Replicas 数量

参考资料

  1. CNCF × Alibaba 云原生技术公开课