## First Steps

Let's see a very simple example. It will be so simple that it is not very useful, for now.

But this way we can focus on how the **Dependency Injection** system works.

### Create a dependency, or "dependable"

Let's first focus on the dependency.

It is just a function that can take all the same parameters that a *path operation function* can take:

=== "Python 3.10+"

But then, the project's focus shifted.

It was no longer an API web framework, as the creator needed to focus on Starlette.

Now APIStar is a set of tools to validate OpenAPI specifications, not a web framework.

!!! info

!!! tip
    In the next chapter, you will see a real secure implementation, with password hashing and <abbr title="JSON Web Tokens">JWT</abbr> tokens.

    But for now, let's focus on the specific details we need.

=== "Python 3.10+"

    ```Python hl_lines="87"
    {!> ../../../docs_src/security/tutorial003_an_py310.py!}
    ```

=== "Python 3.9+"

* If the PR can be simplified in a way, you can ask for that, but there's no need to be too picky, there might be a lot of subjective points of view (and I will have my own as well 🙈), so it's better if you can focus on the fundamental things.

### Tests

* Help me check that the PR has **tests**.

* Check that the tests **fail** before the PR. 🚨

* Then check that the tests **pass** after the PR. ✅

!!! tip
    This Domain Name part is way before HTTPS, but as everything depends on the domain and the IP address, it's worth mentioning it here.

### DNS

Now let's focus on all the actual HTTPS parts.

First, the browser would check with the **DNS servers** what is the **IP for the domain**, in this case, `someapp.example.com`.

In addition to this conversion, `Ingress` requires writing the address it can be reached at in status. This is done by the Ingress Status controller.

#### Gateway

    So let's focus on the main cases, where it could crash entirely in some particular cases **in the future**, and it still makes sense to restart it.

We are going to create the same application as in the SQLAlchemy tutorial ([SQL (Relational) Databases](../tutorial/sql-databases.md){.internal-link target=_blank}).

Most of the code is actually the same.

So, we are going to focus only on the differences.

## File structure

Let's say you have a directory named `my_super_project` that contains a sub-directory called `sql_app` with a structure like this:

```
.
└── sql_app

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

## HTTPS

If we focus just on the **container image** for a FastAPI application (and later the running **container**), HTTPS normally would be handled **externally** by another tool.