MongoDB - 10 Easy steps for Administrator to manage MongoDB Server

MongoDB - Default port - 27017
MongoDB is an open-source document database that provides high performance, high availability, and automatic scaling. MongoDB obviates the need for an Object Relational Mapping (ORM) to facilitate development.

1- Logon to Mongo shell

If you have SSH to Mongo server then use the command below to connect mongo shell. When you have enabled authentication

When authentication not enabled -

$ mongo 

When authentication is enabled -

$ mongo -u amar -p --authenticationDatabase admin

If you will use above command - Default selected database is "test". In order to log-in to the specific database use following command.

$ mongo -u amar -p  --authenticationDatabase admin

2- List all the databases -

Once you are at mongo shell use command  show dbs to list all the database

> show dbs;

3- Print current selected database -

Sometimes, we required checking currently selected database use command db

> db

4- Change database

To change the database use command use database_name

> use admin

In the above example - I switched to database Admin, Now you can perform the required actions on the database name Admin.

5- List all created users in the currently selected database -

In order to check all the created users and their access level- User command show users, It will print all the user's information.

> use admin                  # To select database
> show users                 # To print user details

Above command's output - We can see here username, and what role they have.

6-Change IP binding to the external IP address
By default, MongoDB works with localhost (127.0.0.1) but in our production environment, we require MongoDB access from outside (Example- access from App server). In order to allow outside MongoDB access, We need to modify MongoDB binding to Server IP address.Let's Change MongoDB binding to Sever's IP address:
Modify mongoDB configuration file.

$ vi /etc/mongod.conf

Change bind IP address with Server IP address

# network interfaces
net:
  port: 27017
#  bindIp: 127.0.0.1
  bindIp: 192.168.102.10

Save and Exit from the file.

Restart MongoDB Service.

systemctl restart mongod.service

Check Service Status

systemctl status mongod.service

7- Test Login with Sever IP Address
Use the command below to verify login access

mongo -u amar -p --host 192.168.102.10 --authenticationDatabase admin

8-  Try to connect MongoDB from Windows-based GUI client.

Generally, Developer needs a GUI based client to connect Database server, Here I am using NoSQLbooster client to make a connection from my Windows PC to MongoDB server.

9- Disable Transparent huge page 
Generally, When you logged in to MongoDB server you will get a warning message- 

** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
**        We suggest setting it to 'never' 

To disable this Warning message- Follow the steps below:
Create a file: etc/init.d/disable-transparent-hugepages

$ vi /etc/init.d/disable-transparent-hugepages

Paste followings line to the file and save.

#!/bin/bash
### BEGIN INIT INFO
# Provides:          disable-transparent-hugepages
# Required-Start:    $local_fs
# Required-Stop:
# X-Start-Before:    mongod mongodb-mms-automation-agent
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Disable Linux transparent huge pages
# Description:       Disable Linux transparent huge pages, to improve
#                    database performance.
### END INIT INFO

case $1 in
  start)
    if [ -d /sys/kernel/mm/transparent_hugepage ]; then
      thp_path=/sys/kernel/mm/transparent_hugepage
    elif [ -d /sys/kernel/mm/redhat_transparent_hugepage ]; then
      thp_path=/sys/kernel/mm/redhat_transparent_hugepage
    else
      return 0
    fi

    echo 'never' > ${thp_path}/enabled
    echo 'never' > ${thp_path}/defrag

    re='^[0-1]+$'
    if [[ $(cat ${thp_path}/khugepaged/defrag) =~ $re ]]
    then
      # RHEL 7
      echo 0  > ${thp_path}/khugepaged/defrag
    else
      # RHEL 6
      echo 'no' > ${thp_path}/khugepaged/defrag
    fi

    unset re
    unset thp_path
    ;;
esac

Save and Exit from the file.

Make it executable:

$ sudo chmod 755 /etc/init.d/disable-transparent-hugepages

Enable this script to run at System boot

$ sudo update-rc.d disable-transparent-hugepages defaults

Reboot your System and check Warning message will not come again

10- Restrict database access from specific IP address
In the above example, We were given access to a user on a database with no IP restriction. That means a user can access  MongoDB server's database from any client machine. Let's restrict access to a specific IP address only.
Log on to MongoDB shell 

sudo mongo -u amar -p --host 192.168.102.10 --authenticationDatabase admin

Create New Database and restrict specific IP address Access.

use Amar
db.createUser(
   {
     user: "user1",
     pwd: "redhat",
     roles: [ {role: 'readWrite', db: 'Amar'} ],
     authenticationRestrictions: [ {
        clientSource: ["192.168.102.1"],
        serverAddress: ["192.168.102.10"]
     } ]
   }
)

Now, You can access Database- Amar From Client IP address- 192.168.102.1 only.