Updating certificates for Heroku with Cloudflare

Do you have a app on Heroku, DNS on Cloudflare and your SSL certificate is automatically managed by Heroku?

I do. And yesterday I received email like this:

Hi,

Automated Certificate Management
has failed for the following domains:

Domain 	    ...

Mobile browsers, Let's Encrypt and Heroku

When you start working with SSL and Heroku, (and with Heroku in general), their dashboard
is pretty much self-explaining and easy:

Paste server certificate here, private cert there, change DNS and you are ready.

So what you do is go to where...

Learning how to work with Heroku Buildpacks and Node app

Few days ago I started to work on new task: deployment of the front-end Node app to Heroku.

I am not familiar with it, so what could go wrong? No worries, I have colleagues with more experience, so let's call it time to learn.

First things first...