By Zhu Yansheng
Currently, the worker nodes in Kubernetes clusters support ECS in multiple availability zones. The deployment mode is to make it possible to distribute multiple (two at least) Pods of one application in several different availability zones (at least not in the same availability zone) to implement high availability or local backup for disaster recovery.
To achieve the aforementioned desired effect, Kubernetes provides pod affinity and anti-affinity to ensure high availability deployment of pods at the node level and availability-zone level. The specific value is topologyKey: failure-domain.beta.kubernetes.io/zone.
After a cluster is created on the ACK, each node added from any availability zone will be marked with that availability zone label. For example, a node in Beijing zone A, if added to the Kubernetes cluster, will have a label like this: failure-domain.beta.kubernetes.io/zone: cn-beijing-a.
With this label, we can use the yaml file to assign Pods to different availability zones when we deploy an application in multiple availability zones.
Example yaml file:
apiVersion: apps/v1 kind: Deployment metadata: name: redis-cache spec: selector: matchLabels: app: store replicas: 3 template: metadata: labels: app: store spec: affinity: podAntiAffinity: preferredDuringSchedulingIgnoredDuringExecution: - labelSelector: matchExpressions: - key: app operator: In values: - store topologyKey: "failure-domain.beta.kubernetes.io/zone" containers: - name: redis-server image: redis:3.2-alpine
"podAntiAffinity:" in this yaml file specifies node anti-affinity. In addition, because topologyKey: "failure-domain.beta.kubernetes.io/zone" is used, if the "failure-domain.beta.kubernetes.io/zone" key has three values (for example, cn-beijing-a, cn-beijing-b, andcn-beijing-c), Pods will be assigned to these three availability zones. preferredDuringSchedulingIgnoredDuringExecution allows pods to be assigned to different availability zones as far as possible if the number of Pods is greater than that of availability zones. Remaining extra pods will be assigned to the availability zone where the original Pods are.
Many other methods are available, including deployment at the node level. For more information, visit https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity
Because disks cannot be mounted across availability zones, if a Pod uses volume, that Pod should be scheduled to a machine in the same availability zone as the volume.
Other volumes like NAS and OSS can use the preceding deployment method.
Alibaba Clouder - July 15, 2020
Aliware - July 3, 2020
Apache Flink Community China - September 16, 2020
Alex - November 8, 2018
Alibaba Container Service - February 12, 2021
Alibaba Clouder - June 9, 2020
Alibaba Cloud Container Service for Kubernetes is a fully managed cloud container management service that supports native Kubernetes and integrates with other Alibaba Cloud products.Learn More
Provides a control plane to allow users to manage Kubernetes clusters that run based on different infrastructure resourcesLearn More
Protect, backup, and restore your data assets on the cloud with Alibaba Cloud database services.Learn More
Alibaba Cloud provides products and services to help you properly plan and execute data backup, massive data archiving, and storage-level disaster recovery.Learn More
More Posts by Alibaba Container Service