近期有同学问mongodb副本集难不难部署，我的回答是不难，很快，几分钟搞定，比mysql MHA简单的不止一点半点。 那么到底如何部署呢？请看下文。
1. 准备工作
1.1 下载软件
选择版本并下载mongodb的软件，注意操作系统版本等。本次我选用的是percona分支的mongodb 4.2.8版本搭建，操作系统为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 规划各节点角色
各节点角色如下
2 部署
2.1 创建各节点相关目录
创建数据目录、日志目录等相关目录
[root@m1 ~]# mkdir -p /data/mongodb/27017/{data,logs,tmp,etc,keyfile} [root@m1 ~]# cd /data/mongodb/27017/ [root@m1 27017]# ll 总用量 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 配置文件
创建配置文件，并添加对应的配置信息，注意仲裁节点的端口
[root@m1 27017]# cd /data/mongodb/27017/etc/ [root@m1 etc]# vim mongod.conf 添加如下内容 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" # 副本集名称
2.3 启动各节点
以其中一个节点为例，其他节点修改对应配置文件即可
[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，指定各节点id及角色，注意副本集的名称和配置文件里一致。
在任意节点执行如下语句
> 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) }
完成后可以查看各集群状态,如下，可见当前192.168.128.208:27017 为PRIMARY节点
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 修改为认证模式
为考虑安全性等，需要开启认证模式（需要通过用户名/密码方式登录）
3.1 创建用户
创建超级管理员账号
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 创建key文件
在主库上执行脚本生成key文件，然后将结拷贝到另外2个节点
[root@m1 mongodb]# cd /data/mongodb/27017/keyfile/ [root@m1 keyfile]# openssl rand -base64 756 > mongo.key [root@m1 keyfile]# chmod 600 mongo.key # 必须修改为600权限，否则无法启动
以上完成后，将文件复制到另外2个节点
3.3 修改配置文件
配置文件中 添加如下内容，注意不同节点的文件路径security: authorization: enabled clusterAuthMode: keyFile keyFile: /data/mongodb/27017/keyfile/mongo.key
3.4 重启后并用认证模式登陆
# 关闭mongodb [root@m1 keyfile]# /usr/local/mongodb/bin/mongod -f /data/mongodb/27017/etc/mongod.conf -shutdown killing process with pid: 30675 # 启动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 # 认证模式登陆 [root@m1 keyfile]# [root@m1 keyfile]# /usr/local/mongodb/bin/mongo -u root -p 'Root#123' --authenticationDatabase admin
至此，mongodb 副本集搭建完毕，你会了吗？
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