# Deployments Concepts

When deploying a **FastAPI** application, or actually, any type of web API, there are several concepts that you probably care about, and using them you can find the **most appropriate** way to **deploy your application**.

Some of the important concepts are:

* Security - HTTPS
* Running on startup
* Restarts
* Replication (the number of processes running)
* Memory
* Previous steps before starting

    ---

    The `APIRouter`s are not "mounted", they are not isolated from the rest of the application.

    This is because we want to include their *path operations* in the OpenAPI schema and the user interfaces.

    As we cannot just isolate them and "mount" them independently of the rest, the *path operations* are "cloned" (re-created), not included directly.

## Check the automatic API docs

    ```

#### Using `Union` or `Optional`

If you are using a Python version below 3.10, here's a tip from my very **subjective** point of view:

* 🚨 Avoid using `Optional[SomeType]`
* Instead ✨ **use `Union[SomeType, None]`** ✨.

## Mounting a **FastAPI** application

"Mounting" means adding a completely "independent" application in a specific path, that then takes care of handling everything under that path, with the _path operations_ declared in that sub-application.

### Top-level application

First, create the main, top-level, **FastAPI** application, and its *path operations*:

This code is something you can actually use in your application, save the password hashes in your database, etc.

We are going to start from where we left in the previous chapter and increment it.

## About JWT

JWT means "JSON Web Tokens".

It's a standard to codify a JSON object in a long dense string without spaces. It looks like this:

# ~~Async SQL (Relational) Databases with Encode/Databases~~ (deprecated)

!!! info
    These docs are about to be updated. 🎉

    The current version assumes Pydantic v1.

    The new docs will include Pydantic v2 and will use <a href="https://sqlmodel.tiangolo.com/" class="external-link" target="_blank">SQLModel</a> once it is updated to use Pydantic v2 as well.

!!! warning "Deprecated"

        * Different `dependencies` can be applied to different routers.
    * These `dependencies` are run before the normal parameter dependencies. And normal dependencies are run too. They can be combined.
    * Dependencies declared in a router are executed first, then the ones defined in *path operation decorators*, and then the ones declared in normal parameters. They are all combined and executed.

## Vélemények

"_[...] I'm using **FastAPI** a ton these days. [...] I'm actually planning to use it for all of my team's **ML services at Microsoft**. Some of them are getting integrated into the core **Windows** product and some **Office** products._"

## Opiniones

"_[...] I'm using **FastAPI** a ton these days. [...] I'm actually planning to use it for all of my team's **ML services at Microsoft**. Some of them are getting integrated into the core **Windows** product and some **Office** products._"

컨테이너를 사용하지 않고서는, 어플리케이션을 구동하고 재시작하는 것이 매우 번거롭고 어려울 수 있습니다. 하지만 **컨테이너를 사용한다면** 대부분의 경우에 이런 기능은 기본적으로 포함되어 있습니다. ✨

## 복제 - 프로세스 개수

만약 여러분이 **쿠버네티스**와 머신 <abbr title="A group of machines that are configured to be connected and work together in some way.">클러스터</abbr>, 도커 스왐 모드, 노마드, 또는 다른 여러 머신 위에 분산 컨테이너를 관리하는 복잡한 시스템을 다루고 있다면, 여러분은 각 컨테이너에서 (워커와 함께 사용하는 Gunicorn 같은) **프로세스 매니저** 대신 **클러스터 레벨**에서 **복제를 다루**고 싶을 것입니다.