如果Kubernetes中的MaxUnavailable设置为0，则不替换Pod
如果Kubernetes中的MaxUnavailable设置为0，则不替换Pod
提问于 2019-01-03 14:14:17
我希望对我的pod进行回滚部署。我在CI环境中使用set Image更新我的pod。当我将部署/web文件上的maxUnavailable设置为1时，我得到了停机时间。但是当我将maxUnavailable设置为0时，pods不会被替换，容器/应用程序也不会重启。
另外，我在Kubernetes集群中只有一个节点，下面是它的信息
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
CPU Requests CPU Limits Memory Requests Memory Limits
------------ ---------- --------------- -------------
881m (93%) 396m (42%) 909712Ki (33%) 1524112Ki (56%)
Events: <none>下面是完整的YAML文件。我确实设置了就绪探头。
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "10"
kompose.cmd: C:\ProgramData\chocolatey\lib\kubernetes-kompose\tools\kompose.exe
convert
kompose.version: 1.14.0 (fa706f2)
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"extensions/v1beta1","kind":"Deployment","metadata":{"annotations":{"kompose.cmd":"C:\\ProgramData\\chocolatey\\lib\\kubernetes-kompose\\tools\\kompose.exe convert","kompose.version":"1.14.0 (fa706f2)"},"creationTimestamp":null,"labels":{"io.kompose.service":"dev-web"},"name":"dev-web","namespace":"default"},"spec":{"replicas":1,"strategy":{},"template":{"metadata":{"labels":{"io.kompose.service":"dev-web"}},"spec":{"containers":[{"env":[{"name":"JWT_KEY","value":"ABCD"},{"name":"PORT","value":"2000"},{"name":"GOOGLE_APPLICATION_CREDENTIALS","value":"serviceaccount/quick-pay.json"},{"name":"mongoCon","value":"mongodb://quickpayadmin:quickpay1234@ds121343.mlab.com:21343/quick-pay-db"},{"name":"PGHost","value":"173.255.206.177"},{"name":"PGUser","value":"postgres"},{"name":"PGDatabase","value":"quickpay"},{"name":"PGPassword","value":"z33shan"},{"name":"PGPort","value":"5432"}],"image":"gcr.io/quick-pay-208307/quickpay-dev-node:latest","imagePullPolicy":"Always","name":"dev-web-container","ports":[{"containerPort":2000}],"readinessProbe":{"failureThreshold":3,"httpGet":{"path":"/","port":2000,"scheme":"HTTP"},"initialDelaySeconds":5,"periodSeconds":5,"successThreshold":1,"timeoutSeconds":1},"resources":{"requests":{"cpu":"20m"}}}]}}}}
creationTimestamp: 2018-12-24T12:13:48Z
generation: 12
labels:
io.kompose.service: dev-web
name: dev-web
namespace: default
resourceVersion: "9631122"
selfLink: /apis/extensions/v1beta1/namespaces/default/deployments/web
uid: 5e66f7b3-0775-11e9-9653-42010a80019d
spec:
progressDeadlineSeconds: 600
replicas: 2
revisionHistoryLimit: 10
selector:
matchLabels:
io.kompose.service: web
strategy:
rollingUpdate:
maxSurge: 1
maxUnavailable: 0
type: RollingUpdate
template:
metadata:
creationTimestamp: null
labels:
io.kompose.service: web
spec:
containers:
- env:
- name: PORT
value: "2000"
image: gcr.io/myimagepath/web-node
imagePullPolicy: Always
name: web-container
ports:
- containerPort: 2000
protocol: TCP
readinessProbe:
failureThreshold: 10
httpGet:
path: /
port: 2000
scheme: HTTP
initialDelaySeconds: 10
periodSeconds: 10
successThreshold: 1
timeoutSeconds: 10
resources:
requests:
cpu: 10m
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 30
status:
availableReplicas: 2
conditions:
- lastTransitionTime: 2019-01-03T05:49:46Z
lastUpdateTime: 2019-01-03T05:49:46Z
message: Deployment has minimum availability.
reason: MinimumReplicasAvailable
status: "True"
type: Available
- lastTransitionTime: 2018-12-24T12:13:48Z
lastUpdateTime: 2019-01-03T06:04:24Z
message: ReplicaSet "dev-web-7bd498fc74" has successfully progressed.
reason: NewReplicaSetAvailable
status: "True"
type: Progressing
observedGeneration: 12
readyReplicas: 2
replicas: 2
updatedReplicas: 2我已经尝试了一个复制品，它仍然不能工作。
回答 1
Stack Overflow用户
发布于 2019-01-03 15:43:24
在第一个场景中，kubernetes删除一个实例(maxUnavailable: 1)，并使用新镜像启动实例，并等待~110秒(基于您的就绪探测)，检查新实例是否能够服务于请求。新的pod不能满足请求，但pod处于运行状态，因此它删除第二个旧pod并使用新映像启动它，第二个pod再次等待就绪探测完成。这就是为什么在两个容器之间有一段时间都没有准备好为请求提供服务，从而导致停机的原因。
在第二个senario中，你有maxUnavailable:0，kubernetes首先打开带有新镜像的pod，它不能在大约110秒内处理请求(基于你的就绪探测)，因此它超时并删除带有新镜像的新pod。第二个pod也是如此。因此，您的两个pod都不会更新
因此，原因是您没有为应用程序提供足够的时间来启动和开始服务请求。这就是问题所在。请在您的就绪探测和maxUnavailable: 0中增加failureThreshold的值，它将起作用。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/54017179
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