## Let's Encrypt

Antes de Let's Encrypt, esses certificados HTTPS eram vendidos por terceiros confiáveis.

O processo de aquisição de um desses certificados costumava ser complicado, exigia bastante papelada e os certificados eram bastante caros.

Mas então <a href="https://letsencrypt.org/" class="external-link" target="_blank">Let's Encrypt</a> foi criado.

* Nginx
* HAProxy

## Let's Encrypt

Vor Let's Encrypt wurden diese **HTTPS-Zertifikate** von vertrauenswürdigen Dritten verkauft.

Der Prozess zum Erwerb eines dieser Zertifikate war früher umständlich, erforderte viel Papierarbeit und die Zertifikate waren ziemlich teuer.

Aber dann wurde **<a href="https://letsencrypt.org/" class="external-link" target="_blank">Let's Encrypt</a>** geschaffen.

## Testing: extended example

Now let's extend this example and add more details to see how to test different parts.

### Extended **FastAPI** app file

Let's continue with the same file structure as before:

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

Now you can translate it all and see how it looks as you save the file.

#### New Language

Let's say that you want to add translations for a language that is not yet translated, not even some pages.

Let's say you want to add translations for Creole, and it's not yet there in the docs.

Checking the link from above, the code for "Creole" is `ht`.

    ```Python hl_lines="10"
    {!> ../../../docs_src/security/tutorial001.py!}
    ```

But that is still not that useful.

Let's make it give us the current user.

## Create a user model

First, let's create a Pydantic user model.

The same way we use Pydantic to declare bodies, we can use it anywhere else:

=== "Python 3.10+"

    ```Python hl_lines="5  12-16"

    pass


@app.post("/invoices/", callbacks=invoices_callback_router.routes)
def create_invoice(invoice: Invoice, callback_url: Union[HttpUrl, None] = None):
    """
    Create an invoice.

    This will (let's imagine) let the API user (some external developer) create an
    invoice.

    And this path operation will:

    * Send the invoice to the client.
    * Collect the money from the client.

* Nginx
* HAProxy

## Let's Encrypt

Before Let's Encrypt, these **HTTPS certificates** were sold by trusted third parties.

The process to acquire one of these certificates used to be cumbersome, require quite some paperwork and the certificates were quite expensive.

But then **<a href="https://letsencrypt.org/" class="external-link" target="_blank">Let's Encrypt</a>** was created.

# Security - First Steps

Let's imagine that you have your **backend** API in some domain.

And you have a **frontend** in another domain or in a different path of the same domain (or in a mobile application).

And you want to have a way for the frontend to authenticate with the backend, using a **username** and **password**.

We can use **OAuth2** to build that with **FastAPI**.

Several of these are explored in the next chapters of the tutorial.

## Order matters

When creating *path operations*, you can find situations where you have a fixed path.

Like `/users/me`, let's say that it's to get data about the current user.

And then you can also have a path `/users/{user_id}` to get data about a specific user by some user ID.

The main idea is exactly the same you saw in that previous chapter.

## Add tests for the SQL app

Let's update the example from [SQL (Relational) Databases](../tutorial/sql-databases.md){.internal-link target=_blank} to use a testing database.

All the app code is the same, you can go back to that chapter check how it was.