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

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

Simple code to run one spec multiple times:

for i in `seq 10`; do rspec spec; done

Redis is quite easy to use, it's just basic key->value database which can be used in many different cases.

Let's assume, we already have Redis server setup in our application, and only need to use it.

Here is my small cheatsheet which will help you to extend any Ruby class.

I found out it very helpful and i hope, it will also be a nice help for you.