K8ssandra入门教程之Linux上部署K8ssandra到Kubernetes的过程

目录

• 1 什么是K8ssandra
• 2 安装K8ssandra
• 2.1 安装Kubenetes
• 2.2 安装helm3
• 2.3 用Helm安装K8ssandra
• 2.4 增加节点
• 3 查看监控
• 4 总结

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上搭建Kubernetes，在文章《VirtualBox+Ubuntu16搭建Kubernetes集群的实现》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

Reference:

Apache Cassandra Operations in Kubernetes

K8ssandra Get Started

Install K8ssandra on GKE

K8ssandra Helm Chart

用Helm部署Kubernetes应用，支持多环境部署与版本回滚

附：

使用到的镜像：

root@k8ssandra:~# docker images | sort | grep -v REPOSITORY | grep -v k8s.gcr.io
alpine                                                   3.12.2            b14afc6dfb98   9 months ago    5.57MB
busybox                                                  1.33.1            16ea53ea7c65   2 weeks ago     1.24MB
busybox                                                  latest            16ea53ea7c65   2 weeks ago     1.24MB
datastax/cass-config-builder                             1.0.4             907e52ff2f78   4 months ago    354MB
gcr.io/k8s-minikube/storage-provisioner                  v5                6e38f40d628d   6 months ago    31.5MB
grafana/grafana                                          7.3.5             71716d95fc52   9 months ago    187MB
jettech/kube-webhook-certgen                             v1.5.0            344297e197b6   11 months ago   44.7MB
k8ssandra/cass-management-api                            3.11.10-v0.1.27   e88cc3a8ce75   2 months ago    877MB
k8ssandra/cass-management-api                            4.0.0-v0.1.28     59b9869dd160   7 weeks ago     726MB
k8ssandra/cass-operator                                  v1.7.1            dd57363b0794   4 months ago    49.4MB
k8ssandra/k8ssandra-tools                                latest            43e4bd91cf9b   42 hours ago    49MB
k8ssandra/reaper-operator                                v0.3.3            b4cb9084a5e5   2 months ago    45.9MB
k8ssandra/system-logger                                  9c4c3692          4dda0db106cb   4 months ago    5.66MB
kiwigrid/k8s-sidecar                                     1.1.0             f4bb3bf1ddc7   11 months ago   82MB
quay.io/prometheus-operator/prometheus-config-reloader   v0.44.0           73bc771f8028   10 months ago   13.4MB
quay.io/prometheus-operator/prometheus-operator          v0.44.0           f5ab8d7a1a64   10 months ago   42.6MB
quay.io/prometheus/prometheus                            v2.22.1           7cc97b58fb0e   10 months ago   168MB
rancher/local-path-provisioner                           v0.0.20           933989e1174c   2 months ago    35MB
stargateio/stargate-3_11                                 v1.0.29           c276fffd9964   3 months ago    537MB
stargateio/stargate-4_0                                  v1.0.29           be4bae3748e1   3 months ago    546MB
thelastpickle/cassandra-reaper                           2.3.1             8ad2c2784ead   2 months ago    418MB

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