MongoDB: Server has startup warnings [duplicate]

Answer 1

• Select the target DB (Exp : use admin)
• Create user in the selected DB

Select the required DB (exp use admin)

db.createUser(
   {
     user: "root",
     pwd: "root",
     roles: [ "readWrite", "dbAdmin" ]
   }
)

The above command will create the root user with roles readWrite and dbAdmin in the admin DB. more info about roles

Now, run the server in authentication mode using mongod --auth

Run client and provide username and password to login using db.auth("root","root")