When you try to run application, for example on Amazon Linux server, and trying to connect it
with a domain with the use of NGINX you can encounter some problematic issue.

You're starting server but, and it works, but when you try to make POST request, you're getting 422 Unprocessable Entity error.

This is because your application is still sending localhost Header, an this is not recognized by the app.

To fix this you need to modify your NGINX configuration

There are two simple ways to run application on Amazon EC2.

One is to run screen command and run application there as a process.

Second one, probably better, is to create SystemCTL Service which you can run later.

This is how to do it:

This is how i usually create a simple Docker container for Python code:

SOLID is a popular group of design principles and if you are a developer, for sure you had contact with it.

It is must if you want to get a nice job, but still many programmers have a problem to deal with this in 100%.

This is my explanation what is SOLID about in Ruby ecosystem.

In simple words CQRS is dividing the reading part of the model from the writing part.

Instead of one, we have 2 models with different responsibilities.

Value Object is quite popular design pattern, but it can be messy to implement it well.

This is my implementation of value objects.