K8ssandra入门-详细记录在Linux上部署K8ssandra到Kubernetes

2021/10/2 7:12:37

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1 什么是K8ssandra

Cassandra是一款非常优秀的开源的分布式NoSQL数据库,被许多优秀的大公司采用,具有高可用、弹性扩展、性能好等特点。

正应Cassandra的优势,我们经常需要在云上服务使用,则需要部署Cassandra到K8s上,这就有了K8ssandra。K8ssandra不仅帮助我们可以快速可靠地在Kubernetes上部署Cassandra,同时提供了许多组件,如监控、备份、同步、访问等。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:保证整个集群正常运行;
  • Reaper:保证一致性的同步工具;
  • Medusa:数据备份工具,支持S3、GCP Cloud Storage等;
  • Stargate:对数据访问提供API;
  • Prometheus+Grafana:云原生的常用监控组件。

2 安装K8ssandra

2.1 安装Kubenetes

如何在Ubuntu上通过Minikube快速启动一个Kubernetes,在文章《服务网格Istio入门-详细记录Kubernetes安装Istio并使用》已经有详细的介绍,这里不再赘述。为了更好的兼容性,我们指定了Kubernetes的版本,命令如下:

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

因为要用到PVC,我们创建一个StorageClass:

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

2.2 安装helm3

我们需要使用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
# 移动到bin目录
mv linux-amd64/helm /usr/local/bin/helm

添加Helm的仓库:

helm repo add k8ssandra https://helm.k8ssandra.io/stable

$ helm repo list
NAME            URL                             
k8ssandra       https://helm.k8ssandra.io/stable
traefik         https://helm.traefik.io/traefik 

查找一下K8ssandra相关的包:

$ helm search repo k8ssandra
NAME                            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...                       

我们安装k8ssandra/k8ssandra就可以了。

2.3 用Helm安装K8ssandra

Helm是一个Chart+Value的管理方式,我们准备一个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

安装K8ssandra:

$ helm install -f k8ssandra-values.yaml k8ssandra k8ssandra/k8ssandra
NAME: k8ssandra
LAST DEPLOYED: Thu Sep 30 21:20:49 2021
NAMESPACE: default
STATUS: deployed
REVISION: 1

做一些必要的检查如下:

$ helm list
NAME            NAMESPACE       REVISION        UPDATED                                 STATUS          CHART           APP VERSION
k8ssandra       default         1               2021-09-30 21:20:49.409672869 +0800 CST deployed        k8ssandra-1.3.1            

$ kubectl get cassandradatacenters
NAME   AGE
dc1    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密码

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

$ kubectl get secret k8ssandra-superuser -o jsonpath="{.data.password}" | base64 --decode ; echo
TNE5xOk45C1aQsj29qxw

2.4 增加节点

我们为了高可用和容量,创建更多的Cassandra Node,直接修改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: racks3
kube-prometheus-stack:
  grafana:
    adminUser: admin
    adminPassword: admin123 
stargate:
  enabled: true
  replicas: 1
  heapMB: 256
  cpuReqMillicores: 200
  cpuLimMillicores: 1000

修改完之后,升级配置:

$ helm upgrade -f k8ssandra-values.yaml k8ssandra k8ssandra/k8ssandra
Release "k8ssandra" has been upgraded. Happy Helming!
NAME: k8ssandra
LAST DEPLOYED: Fri Oct  1 00:40:08 2021
NAMESPACE: default
STATUS: deployed
REVISION: 2

查看Kubernetes的相关资源:

3 查看监控

我们对外暴露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,访问: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项目,后续再介绍如何在开发中通过K8ssandra使用Cassandra吧。

代码请查看:https://github.com/LarryDpk/pkslow-samples



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