1哪些是K8ssandra
Cassandra是一款十分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、弹性扩充、性能好等特性。
正应Cassandra的优势,我们常常须要在云上服务使用,则须要布署Cassandra到K8s上,这就有了K8ssandra。K8ssandra除了帮助我们可以快速可靠地在Kubernetes上布署Cassandra,同时提供了许多组件,如监控、备份、同步、访问等。而那些都是一个Production-Ready的产品不可或缺的。
K8ssandra的组件构架图如下:
2安装K8ssandra2.1安装Kubenetes
怎样在Ubuntu上通过Minikube快速启动一个Kubernetes,在文章《服务网格Istio入门-详尽记录Kubernetes安装Istio并使用》已经有详尽的介绍linux基础教程,这儿不再赘言。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
由于要用到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
我们须要使用Helm来布署K8ssandralinux操作系统怎么样,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的库房:
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的管理方法,我们打算一个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
做一些必要的检测如下:
$ 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
检测一下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降低节点
我们为了高可用和容量,创建更多的CassandraNodelinux 启动cassandra,直接更改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
更改完以后linux 启动cassandra,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
我们对外曝露Grafana服务来瞧瞧:
kubectl expose deployment k8ssandra-grafana --type=NodePort --name=grafana-out
找到对应的NodePort的端口30348,访问:内网IP:30348
帐号: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,后续再介绍怎样在开发中通过K8ssandra使用Cassandra吧。