Let's say, you have a Rails app packed inside docker container. You also have a pg server installed directly on your virtual machine (well, just to save your money). This can be a problem, because on production you should allow only specific ips to have a connection to your database.

How you can do it then? This is a tutorial.

If you are using Amazon Linux 2 and want to install SSL Certificate for your domains, certbot is a right call.

This is how you can do it, and also additional info about how you can renew existing certificate

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:

5 rules, why we use Foreign Keys in our databases:

1. Relationships establishment - we can create relations between tables, and even inner join relation within one table between two records
2. Data Integrity - for example, you can create an order with client_id for client which does not exist in the database
3. Data consistency and accuracy - when foreign key is defined, it restricts the values that can be inserted or updated in the referencing column
4. Data querying - thanks to the foreign keys we can retrieve data from multiple tables faster and easier
5. Data maintenance - it helps cascading updates and deletions, preventing locks mechanisms

MonkeyPatching in Ruby is actually extremely easy to understand and use.

We can monkey patch any ruby class, and this is how to do it.