Configuring a MongoDB replica set

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Before configuring a MongoDB replica set, we recommend reading the Fault tolerance section. It describes the principles of the fault-tolerant Passwork architecture, the license requirements, and the general component layout.

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Configuring MongoDB replication requires at least three servers. MongoDB must be installed on each server as described in the documentation.

Overview

The example uses three MongoDB servers:

• example.mongo.01
• example.mongo.02
• example.mongo.03

If DNS is not configured, add the records to hosts on every node (the path depends on the operating system):

• Example records:
  • 172.16.X.X example.mongo.01
  • 172.16.X.X example.mongo.02
  • 172.16.X.X example.mongo.03
• Linux — /etc/hosts
• Windows Server — C:\Windows\System32\drivers\etc\hosts

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If you are configuring replication in a Docker build, use the ready-made examples: Migrating from standalone to a replica set or Installation with a pre-configured replica set.

Configuration file location and changing MongoDB parameters

Configuration file location

Depending on the operating system:

• Linux — /etc/mongod.conf
• Windows Server — C:\Program Files\MongoDB\Server\7.0\bin\mongod.cfg

You can check the path from the MongoDB shell:

shell

var cmdLineOpts = db.serverCmdLineOpts();
print("config: " + cmdLineOpts.parsed.config);

Changing the configuration file parameters

Open the configuration file and change or add the parameters (substitute your own host names instead of example.mongo.01, example.mongo.02, example.mongo.03):

shell

# network interfaces
net:
  port: 27017
  bindIp: 0.0.0.0

replication:
  replSetName: rs0

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Indentation in the configuration file matters for the syntax.

• bindIp — the IP addresses on which MongoDB accepts connections. It lets you restrict access to the database.
• replication — the rs0 replica set name used for fault tolerance and data distribution.

After making the changes, restart the MongoDB service:

Linux

systemctl restart mongod.service

Windows Server

net stop MongoDB
net start MongoDB

Initializing the replica set and adding/removing members

Initializing the replica set

Connect to the MongoDB shell on the primary server (example.mongo.01):

shell

mongosh

Run the initialization and add the replica set members:

shell

rs.initiate( {
   _id : "rs0",
   members: [
      { _id: 0, host: "example.mongo.01:27017" },
      { _id: 1, host: "example.mongo.02:27017" },
      { _id: 2, host: "example.mongo.03:27017" }
   ]
})

Check the status:

shell

rs.status()

Adding a node to the replica set

Connect to the replica set:

shell

mongosh --host rs0/example.mongo.01:27017,example.mongo.02:27017,example.mongo.03:27017

Add the node:

shell

rs.add("example.mongo.04:27017")

Check the status:

shell

rs.status()

Removing a node from the replica set

Connect to the replica set (including the node being removed):

shell

mongosh --host rs0/example.mongo.01:27017,example.mongo.02:27017,example.mongo.03:27017,example.mongo.04:27017

Remove the node:

shell

rs.remove("example.mongo.04:27017")

Check the status:

shell

rs.status()

Configuring Passwork to connect to the replica set

Edit the Passwork configuration file — config.env:

shell

MONGODB_URL=mongodb://example.mongo.01:27017,example.mongo.02:27017,example.mongo.03:27017/?replicaSet=rs0
MONGODB_DB=pw
MONGODB_USERNAME=
MONGODB_PASSWORD=

Configuration file location:

• Linux — /var/www/init/config.env
• Windows Server — C:\inetpub\wwwroot\passwork\init\config.env

Save the changes and reload the Passwork web interface page to verify the connection to the replica set.