mongodb 4.0副本集搭建

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

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  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//{data,logs,tmp,etc,keyfile}
[root@m1 ~]# cd /data/mongodb//
[root@m1 ]# ll
总用量
drwxr-xr-x  root root  8月    : data
drwxr-xr-x  root root  8月    : etc
drwxr-xr-x  root root  8月    : keyfile
drwxr-xr-x  root root  8月    : logs
drwxr-xr-x  root root  8月    : 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 ]# cd  /data/mongodb//etc/
[root@m1 etc]# vim mongod.conf
添加如下内容

storage:
  dbPath: /data/mongodb//data
  journal:
    enabled: true
systemLog:
  destination: file
  logAppend: true
  path: /data/mongodb//logs/mongod.log
processManagement:
  fork: true
  pidFilePath: /data/mongodb//tmp/mongod.pid
net:
  port:
  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//etc/mongod.conf
about to fork child process, waiting until server is ready for connections.
forked process:
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: , host: "192.168.128.208:27017" },
... { _id: , host: "192.168.128.209:27017" },
... { _id: , host: "192.168.128.209:28017",arbiterOnly:true }
... ] })
{
    "ok" : ,
    "$clusterTime" : {
        "clusterTime" : Timestamp(, ),
        "signature" : {
            "hash" : BinData(,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
            "keyId" : NumberLong()
        }
    },
    "operationTime" : Timestamp(, )
}

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" : ,
    "term" : NumberLong(),
    "syncingTo" : "",
    "syncSourceHost" : "",
    "syncSourceId" : -,
    "heartbeatIntervalMillis" : NumberLong(),
    "majorityVoteCount" : ,
    "writeMajorityCount" : ,
    "optimes" : {
        "lastCommittedOpTime" : {
            "ts" : Timestamp(, ),
            "t" : NumberLong()
        },
        "lastCommittedWallTime" : ISODate("2020-08-07T11:09:23.663Z"),
        "readConcernMajorityOpTime" : {
            "ts" : Timestamp(, ),
            "t" : NumberLong()
        },
        "readConcernMajorityWallTime" : ISODate("2020-08-07T11:09:23.663Z"),
        "appliedOpTime" : {
            "ts" : Timestamp(, ),
            "t" : NumberLong()
        },
        "durableOpTime" : {
            "ts" : Timestamp(, ),
            "t" : NumberLong()
        },
        "lastAppliedWallTime" : ISODate("2020-08-07T11:09:23.663Z"),
        "lastDurableWallTime" : ISODate("2020-08-07T11:09:23.663Z")
    },
    "lastStableRecoveryTimestamp" : Timestamp(, ),
    "lastStableCheckpointTimestamp" : Timestamp(, ),
    "electionCandidateMetrics" : {
        "lastElectionReason" : "electionTimeout",
        "lastElectionDate" : ISODate("2020-08-07T09:31:33.409Z"),
        "electionTerm" : NumberLong(),
        "lastCommittedOpTimeAtElection" : {
            "ts" : Timestamp(, ),
            "t" : NumberLong(-)
        },
        "lastSeenOpTimeAtElection" : {
            "ts" : Timestamp(, ),
            "t" : NumberLong(-)
        },
        "numVotesNeeded" : ,
        "priorityAtElection" : ,
        "electionTimeoutMillis" : NumberLong(),
        "numCatchUpOps" : NumberLong(),
        "newTermStartDate" : ISODate("2020-08-07T09:31:33.444Z"),
        "wMajorityWriteAvailabilityDate" : ISODate("2020-08-07T09:31:34.050Z")
    },
    "members" : [
        {
            "_id" : ,
            "name" : "192.168.128.208:27017",
            "health" : ,
            "state" : ,
            "stateStr" : "PRIMARY",
            "uptime" : ,
            "optime" : {
                "ts" : Timestamp(, ),
                "t" : NumberLong()
            },
            "optimeDate" : ISODate("2020-08-07T11:09:23Z"),
            "syncingTo" : "",
            "syncSourceHost" : "",
            "syncSourceId" : -,
            "infoMessage" : "",
            "electionTime" : Timestamp(, ),
            "electionDate" : ISODate("2020-08-07T09:31:33Z"),
            "configVersion" : ,
            "self" : true,
            "lastHeartbeatMessage" : ""
        },
        {
            "_id" : ,
            "name" : "192.168.128.209:27017",
            "health" : ,
            "state" : ,
            "stateStr" : "SECONDARY",
            "uptime" : ,
            "optime" : {
                "ts" : Timestamp(, ),
                "t" : NumberLong()
            },
            "optimeDurable" : {
                "ts" : Timestamp(, ),
                "t" : NumberLong()
            },
            "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(),
            "lastHeartbeatMessage" : "",
            "syncingTo" : "192.168.128.208:27017",
            "syncSourceHost" : "192.168.128.208:27017",
            "syncSourceId" : ,
            "infoMessage" : "",
            "configVersion" :
        },
        {
            "_id" : ,
            "name" : "192.168.128.209:28017",
            "health" : ,
            "state" : ,
            "stateStr" : "ARBITER",
            "uptime" : ,
            "lastHeartbeat" : ISODate("2020-08-07T11:09:23.672Z"),
            "lastHeartbeatRecv" : ISODate("2020-08-07T11:09:22.952Z"),
            "pingMs" : NumberLong(),
            "lastHeartbeatMessage" : "",
            "syncingTo" : "",
            "syncSourceHost" : "",
            "syncSourceId" : -,
            "infoMessage" : "",
            "configVersion" :
        }
    ],
    "ok" : ,
    "$clusterTime" : {
        "clusterTime" : Timestamp(, ),
        "signature" : {
            "hash" : BinData(,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
            "keyId" : NumberLong()
        }
    },
    "operationTime" : Timestamp(, )
}
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//keyfile/
[root@m1 keyfile]# openssl rand -base64  > mongo.key
[root@m1 keyfile]# chmod  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//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//etc/mongod.conf  -shutdown
killing process with pid:
# 启动mongodb
[root@m1 keyfile]#  /usr/local/mongodb/bin/mongod   -f /data/mongodb//etc/mongod.conf about to fork child process, waiting until server is ready for connections.
forked process: 

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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