k8s滚动发布功能从理论到实战

野性酷女 2024-03-23 17:09 46阅读 0赞

### 一，滚动发布简介 ###

### 滚动发布 ###

![60ed8d28c7c54b58b38d4ce1441dab4e.png][]

*  滚动发布，则是我们一般所说的无宕机发布。其发布方式如同名称一样，一次取出一台/多台服务器（看策略配置）进行新版本更新。当取出的服务器新版确保无问题后，接着采用同等方式更新后面的服务器
 *  k8s创建副本应用程序的最佳方法就是部署(Deployment)，部署自动创建副本集(ReplicaSet)，副本集可以精确地控制每次替换的Pod数量，从而可以很好的实现滚动更新
 *  k8s每次使用一个新的副本控制器(replication controller)来替换已存在的副本控制器，从而始终使用一个新的Pod模板来替换旧的pod模板
    
     *  创建一个新的 replication controller；
     *  增加或减少 pod 副本数量，直到满足当前批次期望的数量；
     *  删除掉旧的 replication controller；

### 发布流程和策略 ###

*  优点
    
     *  不需要停机更新，无感知平滑更新。
     *  版本更新成本小,不需要新旧版本共存
 *  缺点
    
     *  更新时间长：每次只更新一个/多个镜像，需要频繁连续等待服务启动缓冲
     *  旧版本环境无法得到备份：始终只有一个环境存在
     *  回滚版本异常：如果滚动发布到一半出了问题，回滚时需要使用同样的滚动策略回滚旧版本

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

### 二、环境初始化 ###

由于 k8s-node 资源问题，先清理一下 k8s-node 上的资源占用；

#### 查看资源情况 ####

[root@k8s-master deployment]# kubectl get deploy
    NAME      READY   UP-TO-DATE   AVAILABLE   AGE
    nginx     0/3     3            0           2d1h
    pay-v1    0/3     3            0           6h52m
    user-v1   0/3     3            0           8m11s
    user-v2   0/3     3            0           5h11m
    
    [root@k8s-master deployment]# kubectl get service
    NAME              TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
    kubernetes        ClusterIP   10.96.0.1        <none>        443/TCP        2d16h
    nginx             NodePort    10.107.223.32    <none>        80:32117/TCP   2d1h
    service-pay-v1    NodePort    10.106.98.218    <none>        80:30872/TCP   6h32m
    service-user-v1   NodePort    10.104.13.40     <none>        80:31071/TCP   28h
    service-user-v2   NodePort    10.100.196.142   <none>        80:30289/TCP   5h12m
    
    [root@k8s-master deployment]# kubectl get pods
    NAME                       READY   STATUS             RESTARTS   AGE
    mysql-g2zst                0/1     CrashLoopBackOff   53         2d
    nginx-6799fc88d8-2wvl2     1/1     Running            1          2d1h
    nginx-6799fc88d8-lkct4     1/1     Running            1          2d1h
    nginx-6799fc88d8-pktqq     1/1     Running            1          2d1h
    pay-v1-655587b6f5-lpft2    1/1     Running            1          6h41m
    pay-v1-655587b6f5-pcnrp    1/1     Running            2          6h42m
    pay-v1-655587b6f5-spj85    1/1     Running            1          6h41m
    user-v1-5895c69847-8tkm9   0/1     Pending            0          9m18s
    user-v1-5895c69847-swp52   0/1     Pending            0          9m18s
    user-v1-5895c69847-xr4r8   0/1     Pending            0          9m18s
    user-v2-fc9d84585-2zztd    1/1     Running            2          5h13m
    user-v2-fc9d84585-ss2ss    1/1     Running            1          5h13m
    user-v2-fc9d84585-xrvnf    1/1     Running            1          5h13m

#### 删除无用 pod ####

> 注意：想要删除 pod，需要删除掉 deployment，否则副本依然还在；

以 nginx 为例：目前的有 3 个正在运行的 nginx 副本

[root@k8s-master deployment]# kubectl get pods
    NAME                       READY   STATUS    RESTARTS   AGE
    mysql-4nq2q                0/1     Pending   0          4m19s
    nginx-6799fc88d8-2wvl2     1/1     Running   1          2d1h
    nginx-6799fc88d8-lkct4     1/1     Running   1          2d2h
    nginx-6799fc88d8-pktqq     1/1     Running   1          2d1h
    pay-v1-655587b6f5-lpft2    1/1     Running   1          6h53m
    pay-v1-655587b6f5-pcnrp    1/1     Running   2          6h53m
    pay-v1-655587b6f5-spj85    1/1     Running   1          6h53m
    user-v1-5895c69847-8tkm9   0/1     Pending   0          20m
    user-v1-5895c69847-swp52   0/1     Pending   0          20m
    user-v1-5895c69847-xr4r8   0/1     Pending   0          20m
    user-v2-fc9d84585-2zztd    1/1     Running   2          5h24m
    user-v2-fc9d84585-ss2ss    1/1     Running   1          5h24m
    user-v2-fc9d84585-xrvnf    1/1     Running   1          5h24m
    
    [root@k8s-master deployment]# kubectl get deploy
    NAME      READY   UP-TO-DATE   AVAILABLE   AGE
    nginx     0/3     3            0           2d2h
    pay-v1    0/3     3            0           7h8m
    user-v1   0/3     3            0           23m
    user-v2   0/3     3            0           5h27m

删除 nginx 的 deploy 后，pod 状态变为 Terminating

[root@k8s-master deployment]# kubectl delete deployment nginx
    deployment.apps "nginx" deleted
    
    [root@k8s-master deployment]# kubectl get pods
    NAME                       READY   STATUS        RESTARTS   AGE
    mysql-4nq2q                0/1     Pending       0          9m50s
    nginx-6799fc88d8-2wvl2     1/1     Terminating   1          2d1h
    nginx-6799fc88d8-lkct4     1/1     Terminating   1          2d2h
    nginx-6799fc88d8-pktqq     1/1     Terminating   1          2d1h
    pay-v1-655587b6f5-lpft2    1/1     Terminating   1          6h58m
    pay-v1-655587b6f5-pcnrp    1/1     Terminating   2          6h59m
    pay-v1-655587b6f5-spj85    1/1     Terminating   1          6h58m
    user-v1-5895c69847-8tkm9   0/1     Pending       0          26m
    user-v1-5895c69847-swp52   0/1     Pending       0          26m
    user-v1-5895c69847-xr4r8   0/1     Pending       0          26m
    user-v2-fc9d84585-2zztd    1/1     Terminating   2          5h30m
    user-v2-fc9d84585-ss2ss    1/1     Terminating   1          5h30m
    user-v2-fc9d84585-xrvnf    1/1     Terminating   1          5h30m

继续再删除 pod

[root@k8s-master deployment]# kubectl delete pod nginx-6799fc88d8-2wvl2 --force
    warning: Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource may continue to run on the cluster indefinitely.
    pod "nginx-6799fc88d8-2wvl2" force deleted
    
    [root@k8s-master deployment]# kubectl get pods
    NAME                       READY   STATUS        RESTARTS   AGE
    mysql-4nq2q                0/1     Pending       0          14m
    nginx-6799fc88d8-lkct4     1/1     Terminating   1          2d2h
    nginx-6799fc88d8-pktqq     1/1     Terminating   1          2d1h
    pay-v1-655587b6f5-lpft2    1/1     Terminating   1          7h3m
    pay-v1-655587b6f5-pcnrp    1/1     Terminating   2          7h3m
    pay-v1-655587b6f5-spj85    1/1     Terminating   1          7h3m
    user-v1-5895c69847-8tkm9   0/1     Pending       0          30m
    user-v1-5895c69847-swp52   0/1     Pending       0          30m
    user-v1-5895c69847-xr4r8   0/1     Pending       0          30m
    user-v2-fc9d84585-2zztd    1/1     Terminating   2          5h34m
    user-v2-fc9d84585-ss2ss    1/1     Terminating   1          5h34m
    user-v2-fc9d84585-xrvnf    1/1     Terminating   1          5h34m

重复操作，删除全部无用 pod

这个 mysql 删除不掉

[root@k8s-master deployment]# kubectl get deploy
    NAME      READY   UP-TO-DATE   AVAILABLE   AGE
    user-v1   0/3     3            0           33m
    
    [root@k8s-master deployment]# kubectl get pods
    NAME                       READY   STATUS    RESTARTS   AGE
    mysql-xqsgz                0/1     Pending   0          13s
    user-v1-5895c69847-8tkm9   0/1     Pending   0          35m
    user-v1-5895c69847-swp52   0/1     Pending   0          35m
    user-v1-5895c69847-xr4r8   0/1     Pending   0          35m

#### 删除 Service ####

kubectl delete service service-pay-v1 service-user-v2 nginx
    
    [root@k8s-master deployment]# kubectl get svc
    NAME              TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
    kubernetes        ClusterIP   10.96.0.1      <none>        443/TCP        2d16h
    service-user-v1   NodePort    10.104.13.40   <none>        80:31071/TCP   28h

重启阿里云服务

[root@k8s-master deployment]# kubectl get nodes
    NAME         STATUS   ROLES                  AGE     VERSION
    k8s-master   Ready    control-plane,master   2d16h   v1.20.4
    k8s-node     Ready    <none>                 2d16h   v1.20.4
    
    [root@k8s-master deployment]# kubectl get pods
    NAME                       READY   STATUS    RESTARTS   AGE
    user-v1-5895c69847-8zs9n   1/1     Running   0          20m
    user-v1-5895c69847-tdkhj   1/1     Running   0          20m
    user-v1-5895c69847-xcdwl   1/1     Running   0          20m

测试连接

[root@k8s-master deployment]# curl http://172.17.178.106:31071
    user-v1
    [root@k8s-master deployment]# curl http://172.17.178.105:31071
    user-v1

### 三 ，实现滚动更新 ###

重新做一下，用 user-v1 测试滚动更新

目前基于 deployment-user-v1.yaml 创建了 deployment 部署实例；

基于 user-service-v1.yaml 创建了 service，并创建了 3 个 pod 副本

#### 修改 deployment 配置，实现滚动更新 ####

将 v1 升级成 v3，原始 deployment-user-v1.yaml :

[root@k8s-master deployment]# cat deployment-user-v1.yaml 
    
    apiVersion: apps/v1  #API版本号
    kind: Deployment     #资源类型部署
    metadata:
      name: user-v1      #资源名称
    spec:
      selector:
        matchLabels:
          app: user-v1   #告诉deployment根据规则匹配相应的Pod进行控制和管理，matchLabels字段匹配Pod的label值
      replicas: 3        #声明Pod副本的数量
      template:
        metadata:
          labels:
            app: user-v1 #Pod名称
        spec:            #描述Pod内的容器信息
          containers:
          - name: nginx  #容器的名称
            image: nginx:user-v1 #镜像
            ports:
            - containerPort: 80 #容器内映射的端口

修改 deployment-user-v1.yaml

apiVersion: apps/v1  #API 配置版本
    kind: Deployment     #资源类型
    metadata:
      name: user-v1     #资源名称
    spec:
    + minReadySeconds: 1
    + strategy:
    +   type: RollingUpdate
    +   rollingUpdate:
    +     maxSurge: 1
    +     maxUnavailable: 0
    + selector:
    +   matchLabels:
    +     app: user-v1 #告诉deployment根据规则匹配相应的Pod进行控制和管理，matchLabels字段匹配Pod的label值
      replicas: 10 #声明一个 Pod,副本的数量
      template:
        metadata:
          labels:
            app: user-v1 #Pod的名称
        spec:   #组内创建的 Pod 信息
          containers:
          - name: nginx #容器的名称
    +       image: nginx:user-v3 #使用哪个镜像
            ports:
            - containerPort: 80 #容器内映射的端口

#### 相关参数介绍 ####

<table> 
 <thead> 
  <tr> 
   <th><strong>参数</strong></th> 
   <th><strong>含义</strong></th> 
   <th></th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>minReadySeconds</td> 
   <td>容器接受流量延缓时间：单位为秒，默认为0。如果没有设置的话，k8s会认为容器启动成功后就可以用了。设置该值可以延缓容器流量切分</td> 
   <td>容器启动好了，并不代表服务启动好了，比如还要去连接数据库，初始化缓存等服务初始化工作</td> 
  </tr> 
  <tr> 
   <td>strategy.type = RollingUpdate</td> 
   <td>ReplicaSet 发布类型，声明为滚动发布，默认也为滚动发布</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>strategy.rollingUpdate.maxSurge</td> 
   <td>最多Pod数量：为数字类型/百分比。如果 maxSurge 设置为1，replicas 设置为10，则在发布过程中pod数量最多为10 + 1个（多出来的为旧版本pod，平滑期不可用状态）。maxUnavailable 为 0 时，该值也不能设置为0</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>strategy.rollingUpdate.maxUnavailable</td> 
   <td>升级中最多不可用pod的数量：为数字类型/百分比。当 maxSurge 为 0 时，该值也不能设置为0</td> 
   <td></td> 
  </tr> 
 </tbody> 
</table>

扩容数量，是不包括激增量的

pod 最大数量 = 容量 + 激增数

#### 应用配置 ####

[root@k8s-master deployment]# kubectl apply -f deployment-user-v1.yaml 
    deployment.apps/user-v1 configured

#### 分析更新过程 ####

// 更新前
    [root@k8s-master deployment]# kubectl get pods
    NAME                       READY   STATUS    RESTARTS   AGE
    user-v1-5895c69847-9mdm8   1/1     Running   0          2m49s
    user-v1-5895c69847-wjzfh   1/1     Running   0          2m51s
    user-v1-5895c69847-x8n7z   1/1     Running   0          2m54s
    
    // 开始更新
    [root@k8s-master deployment]# kubectl apply -f deployment-user-v1.yaml 
    deployment.apps/user-v1 configured
    
    // 更新中
    [root@k8s-master deployment]# kubectl get pods
    NAME                       READY   STATUS              RESTARTS   AGE
    user-v1-5895c69847-9mdm8   1/1     Terminating         0          3m27s
    user-v1-5895c69847-wjzfh   1/1     Running             0          3m29s
    user-v1-5895c69847-x8n7z   1/1     Running             0          3m32s
    user-v1-8cc9f4fb5-52hmd    0/1     ContainerCreating   0          0s
    user-v1-8cc9f4fb5-zqj2l    1/1     Running             0          3s
    
    // 更新完成
    [root@k8s-master deployment]# kubectl get pods
    NAME                      READY   STATUS    RESTARTS   AGE
    user-v1-8cc9f4fb5-52hmd   1/1     Running   0          48s
    user-v1-8cc9f4fb5-6l7mz   1/1     Running   0          46s
    user-v1-8cc9f4fb5-zqj2l   1/1     Running   0          51s

验证使用镜像是否变更：

[root@k8s-master deployment]# kubectl describe pod user-v1-8cc9f4fb5-zqj2l
    Name:         user-v1-8cc9f4fb5-zqj2l
    Namespace:    default
    Priority:     0
    Node:         k8s-node/172.17.178.106
    Start Time:   Fri, 24 Dec 2021 18:30:57 +0800
    Labels:       app=user-v1
                  pod-template-hash=8cc9f4fb5
    Annotations:  <none>
    Status:       Running
    IP:           10.244.1.67
    IPs:
      IP:           10.244.1.67
    Controlled By:  ReplicaSet/user-v1-8cc9f4fb5
    Containers:
      nginx:
        Container ID:   docker://436d2058c9a6a85000b2c32a3a87c1b7c892427894db1c7d851adb953ba01e88
        Image:          nginx:user-v3
        Image ID:       nginx@sha256:c3826e7a5cd2abc9f0e92fe02fe4897ab4346539438ce4f6c811371677f7494b
        Port:           80/TCP
        Host Port:      0/TCP
        State:          Running
          Started:      Fri, 24 Dec 2021 18:30:58 +0800
        Ready:          True
        Restart Count:  0
        Environment:    <none>
        Mounts:
          /var/run/secrets/kubernetes.io/serviceaccount from default-token-q4qxd (ro)
    Conditions:
      Type              Status
      Initialized       True 
      Ready             True 
      ContainersReady   True 
      PodScheduled      True 
    Volumes:
      default-token-q4qxd:
        Type:        Secret (a volume populated by a Secret)
        SecretName:  default-token-q4qxd
        Optional:    false
    QoS Class:       BestEffort
    Node-Selectors:  <none>
    Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                     node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
    Events:
      Type    Reason     Age   From               Message
      ----    ------     ----  ----               -------
      Normal  Scheduled  7m8s  default-scheduler  Successfully assigned default/user-v1-8cc9f4fb5-zqj2l to k8s-node
      Normal  Pulled     7m8s  kubelet            Container image "nginx:user-v3" already present on machine
      Normal  Created    7m8s  kubelet            Created container nginx
      Normal  Started    7m8s  kubelet            Started container nginx

是 nginx:user-v3，说明应用已更新成功；

#### 访问 service-user-v1 ####

curl http://172.17.178.105:31071
    curl http://172.17.178.106:31071
    
    [root@k8s-master deployment]# curl http://172.17.178.105:31071
    user-v3
    [root@k8s-master deployment]# curl http://172.17.178.106:31071
    user-v3

###  ###

[60ed8d28c7c54b58b38d4ce1441dab4e.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/23/82a1eba7f4e84f05ace9cf49e17d95e4.png