1 什么是K8ssandra

Cassandra是一款十分优良的开源的分布式NoSQL数据库，被许多优良的大公司采纳，具备高可用、弹性扩大、性能好等特点。

正应Cassandra的劣势，咱们常常须要在云上服务应用，则须要部署Cassandra到K8s上，这就有了K8ssandra。K8ssandra不仅帮忙咱们能够疾速牢靠地在Kubernetes上部署Cassandra，同时提供了许多组件，如监控、备份、同步、拜访等。而这些都是一个Production-Ready的产品不可或缺的。

K8ssandra的组件架构图如下：

Cass-operator：保障整个集群失常运行；
Reaper：保障一致性的同步工具；
Medusa：数据备份工具，反对S3、GCP Cloud Storage等；
Stargate：对数据拜访提供API；
Prometheus+Grafana：云原生的罕用监控组件。

2 装置K8ssandra

2.1 装置Kubenetes

如何在Ubuntu上通过Minikube疾速启动一个Kubernetes，在文章《服务网格Istio入门-具体记录Kubernetes装置Istio并应用》曾经有具体的介绍，这里不再赘述。为了更好的兼容性，咱们指定了Kubernetes的版本，命令如下：

minikube start --driver=none --kubernetes-version=v1.19.13

因为要用到PVC，咱们创立一个StorageClass：

$ kubectl apply -f https://raw.githubusercontent.com/rancher/local-path-provisioner/master/deploy/local-path-storage.yaml

2.2 装置helm3

咱们须要应用Helm来部署K8ssandra，下载Helm3如下：

# 下载安装包curl -LO https://get.helm.sh/helm-v3.7.0-linux-amd64.tar.gz# 解压tar -zxvf helm-v3.7.0-linux-amd64.tar.gz# 挪动到bin目录mv linux-amd64/helm /usr/local/bin/helm

增加Helm的仓库：

helm repo add k8ssandra https://helm.k8ssandra.io/stable$ helm repo listNAME            URL                             k8ssandra       https://helm.k8ssandra.io/stabletraefik         https://helm.traefik.io/traefik

查找一下K8ssandra相干的包：

$ helm search repo k8ssandraNAME                            CHART VERSION   APP VERSION     DESCRIPTION                                       k8ssandra/k8ssandra             1.3.1                           Provisions and configures an instance of the en...k8ssandra/k8ssandra-common      0.28.4                          Helper library containing functions used by man...k8ssandra/k8ssandra-operator    0.31.0          1.0.0           Kubernetes operator which handles the provision...k8ssandra/backup                0.26.0                          Creates a CassandraBackup custom resource insta...k8ssandra/cass-operator         0.31.0          1.8.0           Kubernetes operator which handles the provision...k8ssandra/medusa-operator       0.30.1          0.1.0           Installs and configures the Medusa Operator for...k8ssandra/reaper-operator       0.32.1          0.1.0           Configures and installs the Reaper Operator for...k8ssandra/restore               0.27.1                          Creates a CassandraRestore custom resource inst...

咱们装置k8ssandra/k8ssandra就能够了。

2.3 用Helm装置K8ssandra

Helm是一个Chart+Value的治理形式，咱们筹备一个yaml文件（k8ssandra-values.yaml）来放一些变量：

cassandra:  version: "4.0.0"  cassandraLibDirVolume:    storageClass: local-path    size: 5Gi  allowMultipleNodesPerWorker: true  heap:    size: 1G    newGenSize: 1G  resources:    requests:      cpu: 1000m      memory: 2Gi    limits:      cpu: 1000m      memory: 2Gi  datacenters:  - name: dc1    size: 1    racks:    - name: default kube-prometheus-stack:  grafana:    adminUser: admin    adminPassword: admin123 stargate:  enabled: true  replicas: 1  heapMB: 256  cpuReqMillicores: 200  cpuLimMillicores: 1000

装置K8ssandra：

$ helm install -f k8ssandra-values.yaml k8ssandra k8ssandra/k8ssandraNAME: k8ssandraLAST DEPLOYED: Thu Sep 30 21:20:49 2021NAMESPACE: defaultSTATUS: deployedREVISION: 1

做一些必要的查看如下：

$ helm listNAME            NAMESPACE       REVISION        UPDATED                                 STATUS          CHART           APP VERSIONk8ssandra       default         1               2021-09-30 21:20:49.409672869 +0800 CST deployed        k8ssandra-1.3.1            $ kubectl get cassandradatacentersNAME   AGEdc1    4m34s$ kubectl describe CassandraDataCenter dc1 | grep "Cassandra Operator Progress:"  Cassandra Operator Progress:  Ready

检查一下Pod和Service：

获取K8ssandra超级用户的用户名和明码

$ kubectl get secret k8ssandra-superuser -o jsonpath="{.data.username}" | base64 --decode ; echok8ssandra-superuser$ kubectl get secret k8ssandra-superuser -o jsonpath="{.data.password}" | base64 --decode ; echoTNE5xOk45C1aQsj29qxw

2.4 减少节点

咱们为了高可用和容量，创立更多的Cassandra Node，间接批改k8ssandra-values.yaml如下：

cassandra:  version: "4.0.0"  cassandraLibDirVolume:    storageClass: local-path    size: 5Gi  allowMultipleNodesPerWorker: true  heap:    size: 1G    newGenSize: 1G  resources:    requests:      cpu: 1000m      memory: 2Gi    limits:      cpu: 1000m      memory: 2Gi  datacenters:  - name: dc1    size: 3    racks:    - name: racks1    - name: racks2    - name: racks3kube-prometheus-stack:  grafana:    adminUser: admin    adminPassword: admin123 stargate:  enabled: true  replicas: 1  heapMB: 256  cpuReqMillicores: 200  cpuLimMillicores: 1000

批改完之后，降级配置：

$ helm upgrade -f k8ssandra-values.yaml k8ssandra k8ssandra/k8ssandraRelease "k8ssandra" has been upgraded. Happy Helming!NAME: k8ssandraLAST DEPLOYED: Fri Oct  1 00:40:08 2021NAMESPACE: defaultSTATUS: deployedREVISION: 2

查看Kubernetes的相干资源：

3 查看监控

咱们对外裸露Grafana服务来看看：

kubectl expose deployment k8ssandra-grafana --type=NodePort --name=grafana-out

找到对应的NodePort的端口30348，拜访：http://外网IP:30348

账号：admin/admin123

界面如下，提供良好的监控界面：

4 总结

K8ssandra真是一个不错的开源我的项目，后续再介绍如何在开发中通过K8ssandra应用Cassandra吧。

代码请查看：https://github.com/LarryDpk/p...