My operating system is (include version):

OS Ubuntu 16.04
Amazon free-tier with 1 GB ram. I have also created a swapfile still getting the same error

I installed Certbot with (certbot-auto, OS package manager, pip, etc):

Trying to install with certbot -auto
sudo certbot-auto --debug -v --server https://acme-v01.api.letsencrypt.org/directory certonly -d mydomain.com

I ran this command and it produced this output: