As you guys may or may not know (or may or may not give a fuck), I'm currently part-time studying to get a diploma and get the fuck out of my country. Since I have to write a 40-pages long "end of study dissertation" about something we personnaly have interest in, I decided to teach myself about DevOps.
In order to prepare it, I decided to get a Raspberry Pi, install Docker and Jenkins (as a container) on it, and handle my multiples websites on it, and build a huge fucking website around which I would write my dissertation about.
But man, I'm starting to loose hope, I get to bed at 2 AM every night because I'm trying to make some basic shit work until I realize that I just CAN'T what I want because of tons of reason, so I try to lower my expectations, and it's frustrating. Yesterday, a Ruby on Rails image I created was perfectly working, tonight MySQL throws an "host not authorized for this mysql server" error, and I don't know what the fuck is happening nor if I can do anything about it.

I love teaching myself new stuff, but I have to admit, it's waaay harder than I expected

Forget about everything I could say these last 2 days: I'm having as much fun with Docker than when I first discovered Ruby on Rails 3 years ago 😍
I still don't understand everything with docker-compose & shit but so much things are way more clear when you try them out!

There's very little good use cases for mongo, change my mind.

Prototyping maybe? Rails can prototype, create/update/destroy db schemas really quickly anyways.

If you're doing a web app, there's tons of libs that let you have a store in your app, even a fake mongo on the browser.

Are the reads fast? When I need that, use with redis.

Can it be an actual replacement for an app's db? No. Safety mechanisms that relational dbs have are pretty much must haves for a production level app.
Data type checks, null checks, foreign key checks, query checks.
All this robustness, this safety is something critical to maintain the data of an app sane.

Screw ups in the app layer affecting the data are a lot less visible and don't get noticed immediately (things like this can happen with relational dbs but are a lot less likely)

Let's not even get into mutating structures. Once you pick a structure with mongo, you're pretty much set.
Redoing a structure is manual, and you better have checks afterwards.

But at the same time, this is kind of a pro for mongo, since if there's variable data, as in some fields that are not always present, you don't need to create column for them, they just go into the data.

But you can have json columns in postgres too!

Is it easier to migrate than relational dbs? yes, but docker makes everything easy also.

Rails, React, React-Native, Docker, Kubernetes, Openstack, Jenkins, AWS, Microservices, Realm, MongoDB, PostgresQL, GraphQL (list goes on...), and I'm not even done yet.

6 months was spent learning all of the above because I found a Rails-only monolith on Heroku unsettling. My first batch of containers was just deployed and I couldn't be happier. Love my job.

The project structure is simple. To work with it you need to first build this undocumented ruby-based, severely outdated backed that requires an env file that nobody really knows where it is. Don't worry, setting it up should take no more than half a day. Then just run `docker-compose up`, after that `rails s`. Now in another repo you need to run a python server and a node sass. You need to figure out the name of the compiled file though. Perfect structure!