K8S - 实现statefulset 有状态service的灰度发布

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什么是灰度发布 Canary Release

在这里插入图片描述

参考
理解什么是滚动更新，蓝绿部署，灰度发布以及它们的区别

配置partition in updateStrategy/rollingUpdate

这次我为修改了 statefulset 的1个yaml file
statefulsets/stateful-nginx-without-pvc.yaml:

---
apiVersion: v1 # api version
kind: Service # type of this resource e.g. Pod/Deployment ..
metadata:name: nginx-stateful-service # name of the servicelabels:app: nginx-stateful-service
spec:ports: - port: 80 # port of the service, used to access the servicename: web-portclusterIP: None # the service is not exposed outside the clusterselector: # label of the Pod that the Service is selectingapp: nginx-stateful # only service selector could skip the matchLabels:
---apiVersion: apps/v1
kind: StatefulSet # it's for a stateful application, it's a controller
metadata:name: nginx-statefulset # name of the statefulsetlabels:app: nginx-stateful
spec: # detail descriptionserviceName: "nginx-stateful-service" # name of the service that used to manange the dns,  # must be the same as the service name defined abovereplicas: 3 # desired replica countselector: # label of the Pod that the StatefulSet is managingmatchLabels:app: nginx-statefultemplate: # Pod templatemetadata:labels:app: nginx-statefulspec:containers:- name: nginx-containeimage: nginx:1.25.4 # image of the containerports: # the ports of the container and they will be exposed- containerPort: 80 # the port used by the container servicename: web-portupdateStrategy:rollingUpdate:partition: 2type: RollingUpdate

关键是最后1个block

  updateStrategy:rollingUpdate:partition: 2type: RollingUpdate

rollingUpdate 很容易理解，关键是partition 的值

这个值表示在image 版本更新后，只会更新 pod-index 中index >= partition 的POD, 其他POD保持先版本，这就能同时让两个版本存在一段时间，实现灰度发布

一个例子

首先我们先apply 上面的yaml

[gateman@manjaro-x13 statefulsets]$ kubectl apply -f stateful-nginx-without-pvc.yaml 
service/nginx-stateful-service unchanged
statefulset.apps/nginx-statefulset created

检查pods ， 3个pod 起来了分别是0, 1, 2

[gateman@manjaro-x13 statefulsets]$ kubectl get pods -o wide
NAME                  READY   STATUS    RESTARTS   AGE   IP             NODE        NOMINATED NODE   READINESS GATES
nginx-statefulset-0   1/1     Running   0          12m   10.244.2.120   k8s-node0   <none>           <none>
nginx-statefulset-1   1/1     Running   0          12m   10.244.1.59    k8s-node1   <none>           <none>
nginx-statefulset-2   1/1     Running   0          12m   10.244.3.69    k8s-node3   <none>           <none>

为了更好的present, 我们把pods数量scale 到5个

[gateman@manjaro-x13 statefulsets]$ kubectl scale statefulset nginx-statefulset --replicas=5
statefulset.apps/nginx-statefulset scaled
[gateman@manjaro-x13 statefulsets]$ kubectl get pods -o wide
NAME                  READY   STATUS    RESTARTS   AGE   IP             NODE        NOMINATED NODE   READINESS GATES
nginx-statefulset-0   1/1     Running   0          13m   10.244.2.120   k8s-node0   <none>           <none>
nginx-statefulset-1   1/1     Running   0          13m   10.244.1.59    k8s-node1   <none>           <none>
nginx-statefulset-2   1/1     Running   0          13m   10.244.3.69    k8s-node3   <none>           <none>
nginx-statefulset-3   1/1     Running   0          13s   10.244.2.121   k8s-node0   <none>           <none>
nginx-statefulset-4   1/1     Running   0          12s   10.244.3.70    k8s-node3   <none>           <none>

这时5个pod 起来了

查看每个pod的image 版本

[gateman@manjaro-x13 statefulsets]$ kubectl get pods -o=jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.spec.containers[*].image}{"\n"}{end}'
nginx-statefulset-0	nginx:1.25.4
nginx-statefulset-1	nginx:1.25.4
nginx-statefulset-2	nginx:1.25.4
nginx-statefulset-3	nginx:1.25.4
nginx-statefulset-4	nginx:1.25.4

这时我们更新image 版本从 1.25.4 更新到1.26.1

[gateman@manjaro-x13 statefulsets]$ kubectl set image statefulset/nginx-statefulset nginx-container=nginx:1.26.1
statefulset.apps/nginx-statefulset image updated

再次检查每个pod 的image version

nginx-statefulset-0	nginx:1.25.4
nginx-statefulset-1	nginx:1.25.4
nginx-statefulset-2	nginx:1.26.1
nginx-statefulset-3	nginx:1.26.1
nginx-statefulset-4	nginx:1.26.1

可以见到只有pod 2 3 和4 更新了， 0, 1 还是旧版本

下一步，把新版本应到pod 1 和 pod 0

也很简单，只需要更改partition 的值就行

---
apiVersion: v1 # api version
kind: Service # type of this resource e.g. Pod/Deployment ..
metadata:name: nginx-stateful-service # name of the servicelabels:app: nginx-stateful-service
spec:ports: - port: 80 # port of the service, used to access the servicename: web-portclusterIP: None # the service is not exposed outside the clusterselector: # label of the Pod that the Service is selectingapp: nginx-stateful # only service selector could skip the matchLabels:
---apiVersion: apps/v1
kind: StatefulSet # it's for a stateful application, it's a controller
metadata:name: nginx-statefulset # name of the statefulsetlabels:app: nginx-stateful
spec: # detail descriptionserviceName: "nginx-stateful-service" # name of the service that used to manange the dns,  # must be the same as the service name defined abovereplicas: 5 # desired replica countselector: # label of the Pod that the StatefulSet is managingmatchLabels:app: nginx-statefultemplate: # Pod templatemetadata:labels:app: nginx-statefulspec:containers:- name: nginx-containerimage: nginx:1.26.1 # image of the containerports: # the ports of the container and they will be exposed- containerPort: 80 # the port used by the container servicename: web-portupdateStrategy:rollingUpdate:partition: 1type: RollingUpdate

记得修改3个地方， 1是
replicas: 5 改成当前的数量
image: nginx:1.26.1 要改成新的版本
partition: 1 改成1 就是意思把pod 1 也部署新版本

[gateman@manjaro-x13 statefulsets]$ kubectl replace -f stateful-nginx-without-pvc.yaml 
service/nginx-stateful-service replaced
statefulset.apps/nginx-statefulset replaced

[gateman@manjaro-x13 statefulsets]$ kubectl get pods -o=jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.spec.containers[*].image}{"\n"}{end}'
nginx-statefulset-0	nginx:1.25.4
nginx-statefulset-1	nginx:1.26.1
nginx-statefulset-2	nginx:1.26.1
nginx-statefulset-3	nginx:1.26.1
nginx-statefulset-4	nginx:1.26.1

这时只有pod0 还是旧版本

如何把pod0 也同步？
方法1是用上面的方法重新更新partition 的值为0

方法2使用 kubectl patch 修改
kubectl patch statefulset nginx-statefulset --type=‘json’ -p=‘[{“op”: “replace”, “path”: “/spec/updateStrategy/rollingUpdate/partition”, “value”: 0}]’

[gateman@manjaro-x13 statefulsets]$ kubectl get pods -o=jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.spec.containers[*].image}{"\n"}{end}'
nginx-statefulset-0	nginx:1.26.1
nginx-statefulset-1	nginx:1.26.1
nginx-statefulset-2	nginx:1.26.1
nginx-statefulset-3	nginx:1.26.1
nginx-statefulset-4	nginx:1.26.1

Deployment 的灰度发布

如果是无状态service 的deployment ，可以用这种方法灰度发布吗？
不行
因为 deployment 的pods 的后续不是1个index 数字，无序的，所以无法去比较 pod 的index 和 partition的值

强行写上yaml 就会有如下错误：

[gateman@manjaro-x13 bq-api-service]$ kubectl apply -f bq-api-service-test.yaml 
error: error validating "bq-api-service-test.yaml": error validating data: ValidationError(Deployment.spec.strategy.rollingUpdate): unknown field "partition" in io.k8s.api.apps.v1.RollingUpdateDeployment; if you choose to ignore these errors, turn validation off with --validate=false