I wanted to host my blog on https://blog.many-monkeys.com but I didn't want to host http://www.many-monkeys.com nor http://many-monkeys.com anywhere and wanted to keep my options open i.e. if I wanted to use the domain for more than just a blog.
I still wanted to support https://www... as there are a number of old links out there that point to my old site/blog but I didn't want to pay hosting for a single page that would redirect someone to the blog page. When I read up on this I found some DNS providers have a URL record which is used to configure this sort of behaviour. However I couldn't find out how to configure this sort of record in Cloudflare and so I remained stuck on the single page hosting solution.
The other day I was clicking around the Cloudflare site and I stumbled on the Page Rules and after a bit of trial an error I got it to behave the way I wanted and so I thought I would share.
1. Configure the page rules
I decided to point both names at the blog with a temporary redirect as that will allow me to change it in the future.
2. Configure the DNS
I configured the DNS such that all the domains I wanted to support will route through Cloudflare (the orange cloud image) but instead of being forwarded onto the blog hosting site at ghost.io which would/does fail, the Page Rules above kick-in and do the redirect to blog.many-monkeys.com and all works as I wanted.
By the way you get three free Page Rules and I only needed to use two, I wonder if I'll ever find a need for the third.