近期有同學問mongodb副本集難不難部署，我的回答是不難，很快，幾分鐘搞定，比mysql MHA簡單的不止一點半點。 那麼到底如何部署呢？請看下文。
1. 準備工作
1.1 下載軟體
選擇版本並下載mongodb的軟體，注意作業系統版本等。本次我選用的是percona分支的mongodb 4.2.8版本搭建，作業系統為centos6
cd /usr/local/
wget https://www.percona.com/downloads/percona-server-mongodb-LATEST/percona-server-mongodb-4.2.8-8/binary/tarball/percona-server-mongodb-4.2.8-8-centos6-x86_64.tar.gz
tar -zxvf percona-server-mongodb-4.2.8-8-centos6-x86_64.tar.gz
ln -s percona-server-mongodb-4.2.8-8 mongodb
1.2 規劃各節點角色
各節點角色如下
| IP | port | role |
| 192.168.128.208 | 27017 | PRIMARY |
| 192.168.128.209 | 27017 | SECONDARY |
| 192.168.128.209 | 28017 | ARBITER |
2 部署
2.1 建立各節點相關目錄
建立資料目錄、日誌目錄等相關目錄
[root@m1 ~]# mkdir -p /data/mongodb/27017/{data,logs,tmp,etc,keyfile} [root@m1 ~]# cd /data/mongodb/27017/ [root@m1 27017]# ll 總用量 20 drwxr-xr-x 2 root root 4096 8月 7 16:59 data drwxr-xr-x 2 root root 4096 8月 7 16:59 etc drwxr-xr-x 2 root root 4096 8月 7 16:59 keyfile drwxr-xr-x 2 root root 4096 8月 7 16:59 logs drwxr-xr-x 2 root root 4096 8月 7 16:59 tmp
2.2 配置檔案
建立配置檔案，並新增對應的配置資訊，注意仲裁節點的埠
[root@m1 27017]# cd /data/mongodb/27017/etc/ [root@m1 etc]# vim mongod.conf 新增如下內容 storage: dbPath: /data/mongodb/27017/data journal: enabled: true systemLog: destination: file logAppend: true path: /data/mongodb/27017/logs/mongod.log processManagement: fork: true pidFilePath: /data/mongodb/27017/tmp/mongod.pid net: port: 27017 bindIp: 0.0.0.0
replication:
replSetName: "test1" # 副本集名稱
2.3 啟動各節點
以其中一個節點為例，其他節點修改對應配置檔案即可
[root@m1 local]# /usr/local/mongodb/bin/mongod -f /data/mongodb/27017/etc/mongod.conf about to fork child process, waiting until server is ready for connections. forked process: 30019 child process started successfully, parent exiting
2.4 初始化副本集
初始化副本集，指定各節點id及角色，注意副本集的名稱和配置檔案裡一致。
在任意節點執行如下語句
> use admin switched to db admin > rs.initiate( { ... _id: "test1", ... members: [ ... { _id: 0, host: "192.168.128.208:27017" }, ... { _id: 1, host: "192.168.128.209:27017" }, ... { _id: 2, host: "192.168.128.209:28017",arbiterOnly:true } ... ] }) { "ok" : 1, "$clusterTime" : { "clusterTime" : Timestamp(1596792682, 1), "signature" : { "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="), "keyId" : NumberLong(0) } }, "operationTime" : Timestamp(1596792682, 1) }
完成後可以檢視各叢集狀態,如下，可見當前192.168.128.208:27017 為PRIMARY節點
test1:PRIMARY> rs.status() { "set" : "test1", "date" : ISODate("2020-08-07T11:09:24.454Z"), "myState" : 1, "term" : NumberLong(1), "syncingTo" : "", "syncSourceHost" : "", "syncSourceId" : -1, "heartbeatIntervalMillis" : NumberLong(2000), "majorityVoteCount" : 2, "writeMajorityCount" : 2, "optimes" : { "lastCommittedOpTime" : { "ts" : Timestamp(1596798563, 1), "t" : NumberLong(1) }, "lastCommittedWallTime" : ISODate("2020-08-07T11:09:23.663Z"), "readConcernMajorityOpTime" : { "ts" : Timestamp(1596798563, 1), "t" : NumberLong(1) }, "readConcernMajorityWallTime" : ISODate("2020-08-07T11:09:23.663Z"), "appliedOpTime" : { "ts" : Timestamp(1596798563, 1), "t" : NumberLong(1) }, "durableOpTime" : { "ts" : Timestamp(1596798563, 1), "t" : NumberLong(1) }, "lastAppliedWallTime" : ISODate("2020-08-07T11:09:23.663Z"), "lastDurableWallTime" : ISODate("2020-08-07T11:09:23.663Z") }, "lastStableRecoveryTimestamp" : Timestamp(1596798513, 1), "lastStableCheckpointTimestamp" : Timestamp(1596798513, 1), "electionCandidateMetrics" : { "lastElectionReason" : "electionTimeout", "lastElectionDate" : ISODate("2020-08-07T09:31:33.409Z"), "electionTerm" : NumberLong(1), "lastCommittedOpTimeAtElection" : { "ts" : Timestamp(0, 0), "t" : NumberLong(-1) }, "lastSeenOpTimeAtElection" : { "ts" : Timestamp(1596792682, 1), "t" : NumberLong(-1) }, "numVotesNeeded" : 2, "priorityAtElection" : 1, "electionTimeoutMillis" : NumberLong(10000), "numCatchUpOps" : NumberLong(0), "newTermStartDate" : ISODate("2020-08-07T09:31:33.444Z"), "wMajorityWriteAvailabilityDate" : ISODate("2020-08-07T09:31:34.050Z") }, "members" : [ { "_id" : 0, "name" : "192.168.128.208:27017", "health" : 1, "state" : 1, "stateStr" : "PRIMARY", "uptime" : 5950, "optime" : { "ts" : Timestamp(1596798563, 1), "t" : NumberLong(1) }, "optimeDate" : ISODate("2020-08-07T11:09:23Z"), "syncingTo" : "", "syncSourceHost" : "", "syncSourceId" : -1, "infoMessage" : "", "electionTime" : Timestamp(1596792693, 1), "electionDate" : ISODate("2020-08-07T09:31:33Z"), "configVersion" : 1, "self" : true, "lastHeartbeatMessage" : "" }, { "_id" : 1, "name" : "192.168.128.209:27017", "health" : 1, "state" : 2, "stateStr" : "SECONDARY", "uptime" : 5882, "optime" : { "ts" : Timestamp(1596798563, 1), "t" : NumberLong(1) }, "optimeDurable" : { "ts" : Timestamp(1596798563, 1), "t" : NumberLong(1) }, "optimeDate" : ISODate("2020-08-07T11:09:23Z"), "optimeDurableDate" : ISODate("2020-08-07T11:09:23Z"), "lastHeartbeat" : ISODate("2020-08-07T11:09:23.672Z"), "lastHeartbeatRecv" : ISODate("2020-08-07T11:09:22.804Z"), "pingMs" : NumberLong(0), "lastHeartbeatMessage" : "", "syncingTo" : "192.168.128.208:27017", "syncSourceHost" : "192.168.128.208:27017", "syncSourceId" : 0, "infoMessage" : "", "configVersion" : 1 }, { "_id" : 2, "name" : "192.168.128.209:28017", "health" : 1, "state" : 7, "stateStr" : "ARBITER", "uptime" : 5882, "lastHeartbeat" : ISODate("2020-08-07T11:09:23.672Z"), "lastHeartbeatRecv" : ISODate("2020-08-07T11:09:22.952Z"), "pingMs" : NumberLong(0), "lastHeartbeatMessage" : "", "syncingTo" : "", "syncSourceHost" : "", "syncSourceId" : -1, "infoMessage" : "", "configVersion" : 1 } ], "ok" : 1, "$clusterTime" : { "clusterTime" : Timestamp(1596798563, 1), "signature" : { "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="), "keyId" : NumberLong(0) } }, "operationTime" : Timestamp(1596798563, 1) } test1:PRIMARY>
3 修改為認證模式
為考慮安全性等，需要開啟認證模式（需要通過使用者名稱/密碼方式登入）
3.1 建立使用者
建立超級管理員賬號
test1:PRIMARY> db.createUser({user: "root", pwd: "Root#123", roles: [{role: "root", db: "admin"}]})
Successfully added user: {
"user" : "root",
"roles" : [
{
"role" : "root",
"db" : "admin"
}
]
}
3.2 建立key檔案
在主庫上執行指令碼生成key檔案，然後將結拷貝到另外2個節點
[root@m1 mongodb]# cd /data/mongodb/27017/keyfile/ [root@m1 keyfile]# openssl rand -base64 756 > mongo.key [root@m1 keyfile]# chmod 600 mongo.key # 必須修改為600許可權，否則無法啟動
以上完成後，將檔案複製到另外2個節點
3.3 修改配置檔案
配置檔案中 新增如下內容，注意不同節點的檔案路徑
security: authorization: enabled clusterAuthMode: keyFile keyFile: /data/mongodb/27017/keyfile/mongo.key
3.4 重啟後並用認證模式登陸
# 關閉mongodb [root@m1 keyfile]# /usr/local/mongodb/bin/mongod -f /data/mongodb/27017/etc/mongod.conf -shutdown killing process with pid: 30675 # 啟動mongodb [root@m1 keyfile]# /usr/local/mongodb/bin/mongod -f /data/mongodb/27017/etc/mongod.conf about to fork child process, waiting until server is ready for connections. forked process: 2430 child process started successfully, parent exiting # 認證模式登陸 [root@m1 keyfile]# [root@m1 keyfile]# /usr/local/mongodb/bin/mongo -u root -p 'Root#123' --authenticationDatabase admin
至此，mongodb 副本集搭建完畢，你會了嗎？
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