- 为指定的端点（Endpoint）进行身份验证
    - 因此，用 API 验证身份时，要发送值为 `Bearer` + 令牌的请求头 `Authorization`
    - 假如令牌为 `foobar`，`Authorization` 请求头就是： `Bearer foobar`

## **FastAPI** 的 `OAuth2PasswordBearer`

**FastAPI** 提供了不同抽象级别的安全工具。

本例使用 **OAuth2** 的 **Password** 流以及 **Bearer** 令牌（`Token`）。为此要使用 `OAuth2PasswordBearer` 类。

!!! info "说明"

    `Bearer` 令牌不是唯一的选择。

    但它是最适合这个用例的方案。

Hier ist ein wenig über diese Geschichte.

## Alternativen

Ich habe seit mehreren Jahren APIs mit komplexen Anforderungen (maschinelles Lernen, verteilte Systeme, asynchrone Jobs, NoSQL-Datenbanken, usw.) erstellt und leitete mehrere Entwicklerteams.

Dabei musste ich viele Alternativen untersuchen, testen und nutzen.

Obwohl das [Tutorial – Benutzerhandbuch](../tutorial/index.md){.internal-link target=_blank} und dieses **Handbuch für fortgeschrittene Benutzer** als geführtes Tutorial (wie ein Buch) geschrieben sind und für Sie ausreichen sollten, um **FastAPI zu lernen**, möchten Sie sie vielleicht durch zusätzliche Kurse ergänzen.

Oder Sie belegen einfach lieber andere Kurse, weil diese besser zu Ihrem Lernstil passen.

## External Courses

Although the [Tutorial - User Guide](../tutorial/index.md){.internal-link target=_blank} and this **Advanced User Guide** are written as a guided tutorial (like a book) and should be enough for you to **learn FastAPI**, you might want to complement it with additional courses.

Or it might be the case that you just prefer to take other courses because they adapt better to your learning style.

* 🕸 🏪 👈 🤝 🍕 👱.
* 👩‍💻 🖊 🕸 🚶 ➕1️⃣ 📄 🕸 🕸 📱.
* 🕸 💪 ☕ 🌅 💽 ⚪️➡️ 🛠️.
    * ✋️ ⚫️ 💪 🤝 👈 🎯 🔗.
    * , 🔓 ⏮️ 👆 🛠️, ⚫️ 📨 🎚 `Authorization` ⏮️ 💲 `Bearer ` ➕ 🤝.
    * 🚥 🤝 🔌 `foobar`, 🎚 `Authorization` 🎚 🔜: `Bearer foobar`.

## **FastAPI**'Ⓜ `OAuth2PasswordBearer`

**FastAPI** 🚚 📚 🧰, 🎏 🎚 ⚛, 🛠️ 👫 💂‍♂ ⚒.

  // +optional
  optional TokenReviewStatus status = 3;
}

// TokenReviewSpec is a description of the token authentication request.
message TokenReviewSpec {
  // Token is the opaque bearer token.
  // +optional
  optional string token = 1;

  // Audiences is a list of the identifiers that the resource server presented
  // with the token identifies as. Audience-aware token authenticators will

		* Mas precisa de autenticação para aquele endpoint em específico.
		* Então, para autenticar com nossa API, ele manda um header de `Autorização` com o valor `Bearer` mais o token.
		* Se o token contém `foobar`, o conteúdo do header de `Autorização` será: `Bearer foobar`.

## **FastAPI**'s `OAuth2PasswordBearer`

**FastAPI** fornece várias ferramentas, em diferentes níveis de abstração, para implementar esses recursos de segurança.

##### Cluster

```yaml
scrape_configs:
- job_name: minio-job
  bearer_token: <secret>
  metrics_path: /minio/v2/metrics/cluster
  scheme: http
  static_configs:
  - targets: ['localhost:9000']
```

##### Bucket centric

```yaml
- job_name: minio-job-bucket
  bearer_token: <secret>
  metrics_path: /minio/v2/metrics/bucket
  scheme: http
  static_configs:

    * But it needs authentication for that specific endpoint.
    * So, to authenticate with our API, it sends a header `Authorization` with a value of `Bearer ` plus the token.
    * If the token contains `foobar`, the content of the `Authorization` header would be: `Bearer foobar`.

## **FastAPI**'s `OAuth2PasswordBearer`

**FastAPI** provides several tools, at different levels of abstraction, to implement these security features.

```Python hl_lines="58-67  69-72  90"
{!../../../docs_src/security/tutorial003.py!}
```

!!! info "说明"

    此处返回值为 `Bearer` 的响应头 `WWW-Authenticate` 也是规范的一部分。

    任何 401**UNAUTHORIZED**HTTP（错误）状态码都应返回 `WWW-Authenticate` 响应头。

    本例中，因为使用的是 Bearer Token，该响应头的值应为 `Bearer`。

    实际上，忽略这个附加响应头，也不会有什么问题。

    之所以在此提供这个附加响应头，是为了符合规范的要求。

    说不定什么时候，就有工具用得上它，而且，开发者或用户也可能用得上。

    这就是遵循标准的好处……