什么是灰度发布 Canary Release
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但是灰度发布只是1个思想， 实现的方法有很多种
deployment的灰度发布在k8s 是可行的， 例如简单粗暴地用多个deployment 去cover 不同的instance. 具体方法不在此讨论
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