K8s 滚动发布
一，前言
本篇，介绍滚动发布的实现；
二，滚动发布简介
滚动发布
- 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
三、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
sql复制代码[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
sql复制代码[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
sql复制代码[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
sql复制代码[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
sql复制代码[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
sql复制代码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
sql复制代码[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
arduino复制代码[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
四，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 :
yaml复制代码[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.
yaml复制代码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
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参数
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含义
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minReadySeconds
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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
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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
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strategy.type = RollingUpdate
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ReplicaSet 发布类型，声明为滚动发布，默认也为滚动发布
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strategy.rollingUpdate.maxSurge
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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
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strategy.rollingUpdate.maxUnavailable
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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
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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
sql复制代码[root@k8s-master deployment]# kubectl apply -f deployment-user-v1.yaml deployment.apps/user-v1 configured
分析更新过程
1 sql复制代码// 更新前 2 [root@k8s-master deployment]# kubectl get pods 3 NAME READY STATUS RESTARTS AGE 4 user-v1-5895c69847-9mdm8 1/1 Running 0 2m49s 5 user-v1-5895c69847-wjzfh 1/1 Running 0 2m51s 6 user-v1-5895c69847-x8n7z 1/1 Running 0 2m54s 7 8 // 开始更新 9 [root@k8s-master deployment]# kubectl apply -f deployment-user-v1.yaml 10 deployment.apps/user-v1 configured 11 12 // 更新中 13 [root@k8s-master deployment]# kubectl get pods 14 NAME READY STATUS RESTARTS AGE 15 user-v1-5895c69847-9mdm8 1/1 Terminating 0 3m27s 16 user-v1-5895c69847-wjzfh 1/1 Running 0 3m29s 17 user-v1-5895c69847-x8n7z 1/1 Running 0 3m32s 18 user-v1-8cc9f4fb5-52hmd 0/1 ContainerCreating 0 0s 19 user-v1-8cc9f4fb5-zqj2l 1/1 Running 0 3s 20 21 // 更新完成 22 [root@k8s-master deployment]# kubectl get pods 23 NAME READY STATUS RESTARTS AGE 24 user-v1-8cc9f4fb5-52hmd 1/1 Running 0 48s 25 user-v1-8cc9f4fb5-6l7mz 1/1 Running 0 46s 26 user-v1-8cc9f4fb5-zqj2l 1/1 Running 0 51s
验证使用镜像是否变更：
yaml复制代码[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
arduino复制代码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
