實作給你看：如何在Kubernetes內部署MongoDB

2024/04/08閱讀時間約 10 分鐘

本篇來說明如何在Kubernetes cluster內部署一個MongoDB，相信這種DB解決方案的部署應該都快變成管理員的日常工作之一了，今天透過這個操作演示，讓大家了解在實務上如何把MongoDB成功建立起來，並且還要可以進行基本操作。

本篇將分成以下重點進行說明：

取得Manifests
建立volume
部署實務
基本操作
結論

1.取得Manifests

#-----------------------------------------------
# S1-1. 取得所有manifests
#-----------------------------------------------
[master]# git clone https://github.com/scriptcamp/kubernetes-mongodb.git
[master]# tree .
[master]# kubectl create ns mongodb

#-----------------------------------------------
# S1-2. 建立Secrets
# 使用password來保護DB
#-----------------------------------------------
[master]# vim mongodb-secrets.yaml
apiVersion: v1
data:
  password: cGFzc3dvcmQxMjM= #password123
  username: YWRtaW51c2Vy #adminuser
kind: Secret
metadata:
  creationTimestamp: null
  name: mongo-creds

[master]# kubectl create -f mongodb-secrets.yaml

#-----------------------------------------------
# S1-3. 解開加密物件
# k8s會將所有的secret以base64進行加密，使用以下方式進行解密
#-----------------------------------------------
[master]# echo "cGFzc3dvcmQxMjM=" | base64 --decode
password123

2.建立Volume

建立PVC，從storageclass自動綁定PV

#-----------------------------------------------
# S2-1. 建立PVC
#-----------------------------------------------
[master]# vim mongodb-pvc.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc
spec:
  storageClassName: "managed-nfs-storage"
  accessModes:
    - ReadWriteOnce 
  volumeName: pv
  resources:
    requests:
      storage: 1Gi
      
[master]# kubectl create -f mongodb-pvc.yaml
[master]# kubectl get pvc

3. 部署實務

本LAB建立的MongoDB為Standalone類型，只有一個Pod。

#-----------------------------------------------
# S3-1. 建立Deployment
#-----------------------------------------------
[master]# vim mongodb-deployment.yaml
[master]# kubectl create -f mongodb-deployment.yaml
[master]# kubectl get pod -o wide

#-----------------------------------------------
# S3-2. 建立svc (此處使用nodeport)
#-----------------------------------------------
[master]# vim mongodb-nodeport-svc.yaml
apiVersion: v1
kind: Service
metadata:
  labels:
    app: mongo
  name: mongo-nodeport-svc
spec:
  ports:
  - port: 27017
    protocol: TCP
    targetPort: 27017
    nodePort: 32001
  selector:
    app: mongo
  type: NodePort
  
[master]# kubectl create -f mongodb-nodeport-svc.yaml
[master]# kubectl get svc
NAME                         TYPE       CLUSTER-IP      EXTERNAL-IP   PORT(S)           AGE
service/mongo-nodeport-svc   NodePort   10.103.143.51   <none>        27017:32001/TCP   100m

#-----------------------------------------------
# S3-3. 確認
#-----------------------------------------------
[master]# kubectl exec -it  mongo-5d8b9d77f6-vd4tz /bin/bash
root@mongo-5d8b9d77f6-vd4tz:/# mongosh --host 10.107.88.15 --port 32001 -u adminuser -p password123
=> 出現以下畫面即完成連線

4.基本操作

#---------------------------------------------
# S4-1. Create mongodb client pod
#---------------------------------------------
[master]# vim mongodb-new-client.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: mongo-client
  name: mongo-client
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongo-client
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: mongo-client
    spec:
      containers:
      - image: localhost/mongodb:latest
        name: mongo-client
        env:
        - name: mongo-client_INITDB_ROOT_USERNAME
          value: 'dummy'
        - name: mongo-client_INITDB_ROOT_PASSWORD
          value: 'dummy'
          
[master]# kubectl create -f mongodb-new-client.yaml

#---------------------------------------------
# S4-2. 進入client pod，執行基本操作
#---------------------------------------------
[master]# kubectl exec -it mongo-client-6cb867d578-8pdw6 /bin/bash
root@mongo-client-6cb867d578-8pdw6:/# mongosh --host 10.107.88.15 --port 32001 -u adminuser -p password123

(Display list of DBs)
# show dbs
(Get into DB)
# use db1
(Display a list of collections inside the ‘db1’ database)
# show collections
(Insert data into the db1 database)
# db.blogs.insert({name: "devopscube" })
(Display data from db1 database)
# db.blogs.find()