We will be setting up Mongo DB for high availability using 3 virtual machines
- Mongo Primary (t3a.medium)
- Mongo Secondary (t3a.medium)
- Mongo Arbiter (t3a.small)
Let's begin the system preparations
The following setup has to be done in all 3 machines
- login as sudo in each machine
sudo --login
- Update centos packages to the latest version Centos 7
yum update -y
Centos 8
dnf update -y
- install Nano editor (I am a Nano fan) Centos 7
yum install nano -y
Centos 8
dnf install nano -y
- add hosts values edit the
nano /etc/hostsfile to add the following entries
172.31.28.16 mongo1
172.31.31.194 mongo2
172.31.25.65 mongo3
important Step
Disable SELinux as it has breaking effects on internode connection edit/etc/selinux/config
change
SELINUX=disabled
do the above step in all 3 machines and make sure to do a reboot by running
reboot
Now Install Mongo
- Configure the package management system
Create anano /etc/yum.repos.d/mongodb-org-4.4.repofile so that you can install MongoDB directly using yum
Add the following content to it.
[mongodb-org-4.4]
name=MongoDB Repository
baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/4.4/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/server-4.4.asc
- Install Mongo DB latest Stable Centos 7
yum install -y mongodb-org
Centos 8
dnf install -y mongodb-org
Before we can begin cluster Setup lets prepare mongo
Enable Mongo Authentication
To add authentication to mongo add the following lines to
nano /etc/mongod.conf
security:
authorization: enabled
Then do a restart
service mongod restart
- let's create mongodb user Open mongo shell
mongo
the following commands
use admin
db.createUser({
user: "tomahawk",
pwd: "tomahawkPilot",
roles: [
{
role: "userAdminAnyDatabase",
db: "admin"
},
{
role: "clusterAdmin",
db: "admin"
},
{
role: "root,
db: "admin
}
]
})
Now let's Begin the Replication Configuration
- Add replSet to mongod.conf in all 3 machines edit your
nano /etc/mongod.conffile
replication:
replSetName: rs0
Keyfile Access Control on Replica Set
navigate to your mongo path
/var/lib/mongo in my case
Use the following command to generate a keyfile
openssl rand -base64 756 > keyfile
Copy the key file to all 3 machines add Appropriate permissions
chmod 400 keyfile
chown mongod:mongod keyfile
Now add the keyfile to yournano /etc/mongod.conffile
security:
authorization: enabled
keyFile: /var/lib/mongo/keyfile
- do a restart of all mongod services
systemctl restart mongod
for the changes in replication to take effect before initializing the replica
- On mongo1
use admin
db.auth("tomahawk","tomahawkPilot");
rs.initiate(
{
_id: "rs0",
version: 1,
members: [
{ _id: 0, host : "mongo1:27017" }
]
}
)
You can always run
mongo --port 27017 -u tomahawk --authenticationDatabase 'admin' -p tomahawkPilot
to directly login to the cluster
Now let's create the replica set
rs.add("mongo2:27017");
Check connection status by running
rs.status()
On Successful connection, you will get a response
rs.status()
{
"set" : "rs0",
"date" : ISODate("2020-08-10T14:03:42.405Z"),
"myState" : 1,
"term" : NumberLong(2),
"syncSourceHost" : "",
"syncSourceId" : -1,
"heartbeatIntervalMillis" : NumberLong(2000),
"majorityVoteCount" : 2,
"writeMajorityCount" : 2,
"votingMembersCount" : 2,
"writableVotingMembersCount" : 2,
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1597068221, 2),
"t" : NumberLong(2)
},
"lastCommittedWallTime" : ISODate("2020-08-10T14:03:41.727Z"),
"readConcernMajorityOpTime" : {
"ts" : Timestamp(1597068221, 2),
"t" : NumberLong(2)
},
"readConcernMajorityWallTime" : ISODate("2020-08-10T14:03:41.727Z"),
"appliedOpTime" : {
"ts" : Timestamp(1597068221, 2),
"t" : NumberLong(2)
},
"durableOpTime" : {
"ts" : Timestamp(1597068221, 2),
"t" : NumberLong(2)
},
"lastAppliedWallTime" : ISODate("2020-08-10T14:03:41.727Z"),
"lastDurableWallTime" : ISODate("2020-08-10T14:03:41.727Z")
},
"lastStableRecoveryTimestamp" : Timestamp(1597066170, 1),
"electionCandidateMetrics" : {
"lastElectionReason" : "electionTimeout",
"lastElectionDate" : ISODate("2020-08-10T14:03:41.721Z"),
"electionTerm" : NumberLong(2),
"lastCommittedOpTimeAtElection" : {
"ts" : Timestamp(0, 0),
"t" : NumberLong(-1)
},
"lastSeenOpTimeAtElection" : {
"ts" : Timestamp(1597066987, 1),
"t" : NumberLong(1)
},
"numVotesNeeded" : 2,
"priorityAtElection" : 1,
"electionTimeoutMillis" : NumberLong(10000),
"numCatchUpOps" : NumberLong(0),
"newTermStartDate" : ISODate("2020-08-10T14:03:41.727Z"),
"wMajorityWriteAvailabilityDate" : ISODate("2020-08-10T14:03:41.898Z")
},
"members" : [
{
"_id" : 0,
"name" : "mongo1:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 454,
"optime" : {
"ts" : Timestamp(1597068221, 2),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-10T14:03:41Z"),
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1597068221, 1),
"electionDate" : ISODate("2020-08-10T14:03:41Z"),
"configVersion" : 2,
"configTerm" : 2,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "mongo2:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 7,
"optime" : {
"ts" : Timestamp(1597066987, 1),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1597066987, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2020-08-10T13:43:07Z"),
"optimeDurableDate" : ISODate("2020-08-10T13:43:07Z"),
"lastHeartbeat" : ISODate("2020-08-10T14:03:41.727Z"),
"lastHeartbeatRecv" : ISODate("2020-08-10T14:03:42.261Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"configVersion" : 2,
"configTerm" : 1
}
],
"ok" : 1,
"$clusterTime" : {
"clusterTime" : Timestamp(1597068221, 2),
"signature" : {
"hash" : BinData(0,"17CdXYPWQ6I24TCLhxpQt8nGGPk="),
"keyId" : NumberLong("6859346398467325956")
}
},
"operationTime" : Timestamp(1597068221, 2)
}
rs0:PRIMARY>
Setting up the Arbiter
rs.addArb("mongo3:27017");
{
"ok" : 1,
"$clusterTime" : {
"clusterTime" : Timestamp(1597068567, 1),
"signature" : {
"hash" : BinData(0,"q5F6v883q8+1gBfmEJtwINbXAYY="),
"keyId" : NumberLong("6859346398467325956")
}
},
"operationTime" : Timestamp(1597068567, 1)
}
Now check connection status by running
rs.status()
rs.status()
rs0:PRIMARY> rs.status()
{
"set" : "rs0",
"date" : ISODate("2020-08-10T14:10:18.328Z"),
"myState" : 1,
"term" : NumberLong(2),
"syncSourceHost" : "",
"syncSourceId" : -1,
"heartbeatIntervalMillis" : NumberLong(2000),
"majorityVoteCount" : 2,
"writeMajorityCount" : 2,
"votingMembersCount" : 3,
"writableVotingMembersCount" : 2,
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1597068611, 1),
"t" : NumberLong(2)
},
"lastCommittedWallTime" : ISODate("2020-08-10T14:10:11.737Z"),
"readConcernMajorityOpTime" : {
"ts" : Timestamp(1597068611, 1),
"t" : NumberLong(2)
},
"readConcernMajorityWallTime" : ISODate("2020-08-10T14:10:11.737Z"),
"appliedOpTime" : {
"ts" : Timestamp(1597068611, 1),
"t" : NumberLong(2)
},
"durableOpTime" : {
"ts" : Timestamp(1597068611, 1),
"t" : NumberLong(2)
},
"lastAppliedWallTime" : ISODate("2020-08-10T14:10:11.737Z"),
"lastDurableWallTime" : ISODate("2020-08-10T14:10:11.737Z")
},
"lastStableRecoveryTimestamp" : Timestamp(1597068601, 1),
"electionCandidateMetrics" : {
"lastElectionReason" : "electionTimeout",
"lastElectionDate" : ISODate("2020-08-10T14:03:41.721Z"),
"electionTerm" : NumberLong(2),
"lastCommittedOpTimeAtElection" : {
"ts" : Timestamp(0, 0),
"t" : NumberLong(-1)
},
"lastSeenOpTimeAtElection" : {
"ts" : Timestamp(1597066987, 1),
"t" : NumberLong(1)
},
"numVotesNeeded" : 2,
"priorityAtElection" : 1,
"electionTimeoutMillis" : NumberLong(10000),
"numCatchUpOps" : NumberLong(0),
"newTermStartDate" : ISODate("2020-08-10T14:03:41.727Z"),
"wMajorityWriteAvailabilityDate" : ISODate("2020-08-10T14:03:41.898Z")
},
"members" : [
{
"_id" : 0,
"name" : "mongo1:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 850,
"optime" : {
"ts" : Timestamp(1597068611, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-10T14:10:11Z"),
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1597068221, 1),
"electionDate" : ISODate("2020-08-10T14:03:41Z"),
"configVersion" : 3,
"configTerm" : 2,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "mongo2:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 403,
"optime" : {
"ts" : Timestamp(1597068611, 1),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1597068611, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-10T14:10:11Z"),
"optimeDurableDate" : ISODate("2020-08-10T14:10:11Z"),
"lastHeartbeat" : ISODate("2020-08-10T14:10:17.346Z"),
"lastHeartbeatRecv" : ISODate("2020-08-10T14:10:17.389Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncSourceHost" : "mongo1:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 3,
"configTerm" : 2
},
{
"_id" : 2,
"name" : "mongo3:27017",
"health" : 1,
"state" : 7,
"stateStr" : "ARBITER",
"uptime" : 50,
"lastHeartbeat" : ISODate("2020-08-10T14:10:17.351Z"),
"lastHeartbeatRecv" : ISODate("2020-08-10T14:10:17.471Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"configVersion" : 3,
"configTerm" : 2
}
],
"ok" : 1,
"$clusterTime" : {
"clusterTime" : Timestamp(1597068611, 1),
"signature" : {
"hash" : BinData(0,"Pir6qAUNxIu6/AbFv6fCxpVVwOs="),
"keyId" : NumberLong("6859346398467325956")
}
},
"operationTime" : Timestamp(1597068611, 1)
}
now run
rs.conf()
to see your config
rs0:PRIMARY> rs.conf()
{
"_id" : "rs0",
"version" : 3,
"term" : 2,
"protocolVersion" : NumberLong(1),
"writeConcernMajorityJournalDefault" : true,
"members" : [
{
"_id" : 0,
"host" : "mongo1:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
},
{
"_id" : 1,
"host" : "mongo2:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
},
{
"_id" : 2,
"host" : "mongo3:27017",
"arbiterOnly" : true,
"buildIndexes" : true,
"hidden" : false,
"priority" : 0,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
}
],
"settings" : {
"chainingAllowed" : true,
"heartbeatIntervalMillis" : 2000,
"heartbeatTimeoutSecs" : 10,
"electionTimeoutMillis" : 10000,
"catchUpTimeoutMillis" : -1,
"catchUpTakeoverDelayMillis" : 30000,
"getLastErrorModes" : {
},
"getLastErrorDefaults" : {
"w" : 1,
"wtimeout" : 0
},
"replicaSetId" : ObjectId("5f314b35458f8460ab22cda1")
}
}
Have an awesome day ahead