By default, **FastAPI** will create a `server` in the OpenAPI schema with the URL for the `root_path`.

But you can also provide other alternative `servers`, for example if you want *the same* docs UI to interact with a staging and production environments.

If you pass a custom list of `servers` and there's a `root_path` (because your API lives behind a proxy), **FastAPI** will insert a "server" with this `root_path` at the beginning of the list.

* Grundlegende Startmodelle für Benutzer (ändern und entfernen Sie nach Bedarf).
* **Alembic**-Migrationen.
* **CORS** (Cross Origin Resource Sharing).
* **Celery**-Worker, welche Modelle und Code aus dem Rest des Backends selektiv importieren und verwenden können.

* 📝 Add hyperlink to `docs/en/docs/tutorial/static-files.md`. PR [#10243](https://github.com/tiangolo/fastapi/pull/10243) by [@hungtsetse](https://github.com/hungtsetse).
* 📝 Add External Link: Instrument a FastAPI service adding tracing with OpenTelemetry and send/show traces in Grafana Tempo. PR [#9440](https://github.com/tiangolo/fastapi/pull/9440) by [@softwarebloat](https://github.com/softwarebloat).

werden können.

Wenn Sie jedoch benutzerdefinierte Header haben, die ein Client in einem Browser sehen können soll, müssen Sie diese zu Ihren CORS-Konfigurationen hinzufügen (weitere Informationen finden Sie unter [CORS (Cross-Origin Resource Sharing)](../tutorial/cors.md){.internal-link target=_blank}), unter Verwendung des Parameters `expose_headers`, dokumentiert in <a href="https://www.starlette.io/middleware/#corsmiddleware" class="external-link" target="_blank">Starlettes CORS-Dokumentation</a>....

As code duplication increments the chances of bugs, security issues, code desynchronization issues (when you update in one place but not in the others), etc.

And these models are all sharing a lot of the data and duplicating attribute names and types.

We could do better.

* D'obtenir de nombreuses fonctionnalités supplémentaires (grâce à  Starlette) comme :
    * **WebSockets**
    * de tester le code très facilement avec `requests` et `pytest`
    * **<abbr title="Cross-Origin Resource Sharing">CORS</abbr>**
    * **Cookie Sessions**
    * ... et plus encore.

## Performance

                ```python
                from fastapi import FastAPI

                app = FastAPI(
                    servers=[
                        {"url": "https://stag.example.com", "description": "Staging environment"},
                        {"url": "https://prod.example.com", "description": "Production environment"},
                    ]
                )
                ```
                """
            ),

{
    "openapi": "3.0.2",
    // More stuff here
    "servers": [
        {
            "url": "/api/v1"
        },
        {
            "url": "https://stag.example.com",
            "description": "Staging environment"
        },
        {
            "url": "https://prod.example.com",
            "description": "Production environment"
        }
    ],
    "paths": {
            // More stuff here

## 附加的服务器

!!! warning "警告"

    此用例较难，可以跳过。

默认情况下，**FastAPI** 使用 `root_path` 的链接在 OpenAPI 概图中创建 `server`。

但也可以使用其它备选 `servers`，例如，需要同一个 API 文档与 staging 和生产环境交互。

如果传递自定义 `servers` 列表，并有 `root_path`（ 因为 API 使用了代理），**FastAPI** 会在列表开头使用这个 `root_path` 插入**服务器**。

例如：

```Python hl_lines="4-7"
{!../../../docs_src/behind_a_proxy/tutorial003.py!}
```

!!! info "Technical Details"

    By default SQLite will only allow one thread to communicate with it, assuming that each thread would handle an independent request.

    This is to prevent accidentally sharing the same connection for different things (for different requests).