Create sudo user on Linux

Before provisioning any Linux server, usually some kind of admin user is needed to perform the initial setup (i.e. with Ansible)

To create a sudo user:

1. Connect to VPS ssh root@server_ip_address
2. Create a new user: adduser username --force-badname (--force-badname flag will raise an error if your name contains forbidden or problematic characters)
3. Add new user to the admin group: adduser username admin

4. Modify sudoers file (with visudo, to prevent saving incorrect file) so users of sudo and admin groups can login without password:

    # Members of the admin group may gain root privileges
    %admin ALL=(ALL) NOPASSWD:ALL
   
    # Allow members of group sudo to execute any command
    %sudo   ALL=(ALL:ALL) NOPASSWD:ALL
   

5. Add your SSH key to authorized keys:

   1. sudo su - username
   2. mkdir ~/.ssh
   3. chmod 700 ~/.ssh
   4. touch ~/.ssh/authorized_keys
   5. chmod 644 ~/.ssh/authorized_keys
   6. vim ~/.ssh/authorized_keys
6. Logout and login as a new user to test the setup