It much depends on what exactly you want to do. You can build a simple blogging engine with Flask and Flask-FlatPages, that takes posts in Markdown and generates the HTML. You can generate static pages with Frozen-Flask.

And then you can add as much complexity as you want. If you want a CRUD app, for login, comments, etc, you can use raw SQL, or SQLAlchemy.

I suggest you have a look here: blog.miguelgrinberg.com/post/the-f..., it's a very thorough step-by-step guide that builds a simple blogging engine with Flask. It can give you ideas on how to plan out your CMS, as well. Hope it helps.

Have you considered using Gatsby, or NextJS as the frontend framework and using a headless cms such as Prismic to manage your content?. I used Gatsby to build my blog. Content is created in markdown and the blog is deployed on Netlify which has a free plan. It's pretty convenient.

I suppose the first, biggest question to ask here would be, "Why?" Why create a CMS/Blog engine? There are already several out there. Is there a reason to "Reinvent the wheel"? Perhaps you have an idea... something that Drupal or WordPress or others haven't done, or could do better? Would it make more sense to create a module/plugin for an existing CMS? Perhaps this is just to gain experience. That's great. But you talk about running your own site on this. Realize that it may be some time before your project is ready to meet the world. Don't get me wrong. I'm not saying "Don't"; I'm not trying to discourage you. I'm saying look at the Whole picture, understand your aim, your goal, your reasoning. Understand that writing a CMS from scratch could realistically take several months, to a year or more. Would your goal be better served by digging into the code of existing CMS packages? Many - dare I say most(?) - of us have spent extensive time on projects that were never completed. Ask yourself what is the best way to achieve your desired result.

That look interesting as the three components (Javascript, API, Markdown) is exactly how I imagine my architecture to be. Thanks for the resource!

I just stumbled upon this post and I am pretty late, but if you are still working on that side project: I started a flat-file-cms (called typemill) as a side project three years ago. I run several web projects with it and I still work on it because it is a great way to learn new concepts and new technology. One of the basic learnings was the concept of event driven programming which is one way to enhance a cms with a plugin system (which is very essential in my eyes). There are a lot more challenges like managing forms in some ways, creating or using an ACL (access control layer) for user management and much more. If you want a more API-based aproach then you can learn about JWT (Json Web Tokens), new frontend frameworks like vue or react which are the right way to build admin interfaces today, there are very exciting new content editors like editorjs.io (one of the newest kid on the block) and much more. So you will always have a lot of interesting stuff to play with and the todo list will probably never end. Good luck with your project :)