How2 install and configure MongoDB 4 on CentOS 7

1] To get started we first need add a yum repository

    # vi /etc/yum.repos.d/mongodb-org-4.0.repo

    add the following and save the file

    [mongodb-org-4.0]
    name=MongoDB Repository
    baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/4.0/x86_64/
    gpgcheck=1
    enabled=1
    gpgkey=https://www.mongodb.org/static/pgp/server-4.0.asc

2] Now proceed to install MongoDB

    # yum install mongodb-org

3] Lets configure MongoDB for security and take care of MongoDB warning.

    # vi /etc/mongod.conf

    and to enable security search for

    #security:

    and change it to

    security:
      authorization: enabled

    and save the file

4] We need to disable hugepage which affects the performance on MongoDB and also take care of MongoDB warnings. It is enabled by default in Centos7 and there are various ways to disable it and below is one of them

    # vi /etc/rc.local

    and append following lines at the end of the file and save the file

  if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
      echo never > /sys/kernel/mm/transparent_hugepage/enabled
  fi
  if test -f /sys/kernel/mm/transparent_hugepage/defrag; then
      echo never > /sys/kernel/mm/transparent_hugepage/defrag
  fi

    for it to work we need to make rc.local executable and reboot the server

  # chmod +x /etc/rc.d/rc.local
  # reboot

5]  Login again to start and enable auto start for MongoDB

  # systemctl start mongod && systemctl enable mongod
  # systemctl status mongod

6] Now lets go ahead and connect to MongoDB and create admin user and database to store credential details. Please ensure secure password is used for admin.

    $ mongo
  > use admin
  > db.createUser({user: "admin", pwd: "Password", roles:[{role: "userAdminAnyDatabase", db: "admin"}]})
  > quit()

    and login with admin credentials

    $ mongo -u adminm -p --authenticationDatabase admin

    Now proceed to use MongoDB to create databases, collections etc.