Obtaining "Load key "/root/.ssh/": Is a directory When Executing "ssh -i ~/.ssh root@IP_address
Solution 1:
The -i option requires the name of the private key file, not the name of the directory containing the file:
ssh -i ~/.ssh/id_rsa root@[IP_address of my instance]
However, since ~/.ssh/id_rsa is the default RSA key file, you can omit the -i option and its argument altogether
ssh root@[IP_address of my instance]
Of course, for the authentication to succeed you will need to have copied the public key to the authorized_keys file on the remote account - using ssh-copy-id or otherwise.