1 什麼是K8ssandra
Cassandra是一款非常優秀的開源的分佈式NoSQL數據庫,被許多優秀的大公司採用,具有高可用、彈性擴展、性能好等特點。
正應Cassandra的優勢,我們經常需要在雲上服務使用,則需要部署Cassandra到K8s上,這就有了K8ssandra。K8ssandra不僅幫助我們可以快速可靠地在Kubernetes上部署Cassandra,同時提供了許多組件,如監控、備份、同步、訪問等。而這些都是一個Production-Ready的產品不可或缺的。
K8ssandra的組件架構圖如下:
- Cass-operator:保證整個集羣正常運行;
- Reaper:保證一致性的同步工具;
- Medusa:數據備份工具,支持S3、GCP Cloud Storage等;
- Stargate:對數據訪問提供API;
- Prometheus+Grafana:雲原生的常用監控組件。
2 安裝K8ssandra
2.1 安裝Kubenetes
如何在Ubuntu上通過Minikube快速啓動一個Kubernetes,在文章《服務網格Istio入門-詳細記錄Kubernetes安裝Istio並使用》已經有詳細的介紹,這裏不再贅述。爲了更好的兼容性,我們指定了Kubernetes的版本,命令如下:
minikube start --driver=none --kubernetes-version=v1.19.13
因爲要用到PVC,我們創建一個StorageClass:
$ kubectl apply -f https://raw.githubusercontent.com/rancher/local-path-provisioner/master/deploy/local-path-storage.yaml
2.2 安裝helm3
我們需要使用Helm來部署K8ssandra,下載Helm3如下:
# 下載安裝包
curl -LO https://get.helm.sh/helm-v3.7.0-linux-amd64.tar.gz
# 解壓
tar -zxvf helm-v3.7.0-linux-amd64.tar.gz
# 移動到bin目錄
mv linux-amd64/helm /usr/local/bin/helm
添加Helm的倉庫:
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相關的包:
$ 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...
我們安裝k8ssandra/k8ssandra就可以了。
2.3 用Helm安裝K8ssandra
Helm是一個Chart+Value的管理方式,我們準備一個yaml文件(k8ssandra-values.yaml)來放一些變量:
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
安裝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
做一些必要的檢查如下:
$ 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
檢查一下Pod和Service:
獲取K8ssandra超級用戶的用戶名和密碼
$ 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 增加節點
我們爲了高可用和容量,創建更多的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
修改完之後,升級配置:
$ 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的相關資源:
3 查看監控
我們對外暴露Grafana服務來看看:
kubectl expose deployment k8ssandra-grafana --type=NodePort --name=grafana-out
找到對應的NodePort的端口30348,訪問:http://外網IP:30348
賬號:admin/admin123
界面如下,提供良好的監控界面:
4 總結
K8ssandra真是一個不錯的開源項目,後續再介紹如何在開發中通過K8ssandra使用Cassandra吧。