Force visitors to use SSL by default - Apache2

I am using an Amazon EC2 instance with Ubuntu 14.04 and running an apache2 webserver. I bought my domain with godaddy and migrated the nameservers to cloudflare. Since cloudflare offers free SSL, I have that enabled. I have never built a website to use SSL only and I know this is possible because many websites are SSL by default. So my question is how to have visitors use SSL only site-wide?

Thanks