I’ve scoured this forums and cannot for the life of me find a solution. I’ve tried increasing the swapfile to 1g, I’ve tried installing/redownloading certbot, I’ve tried running --debug and --no-bootstrapping.
You can close this topic - using wget http://dl.eff.org/certbot-auto doesn’t seem to work on raspbian stretch, instead you need to sudo apt-get install certbot, and run certbot certonly commands apparently.