This provider might be charging you per request, and calling it might take some extra time than if you had a fixed mock user for tests.

You probably want to test the external provider once, but not necessarily call it for every test that runs.

In this case, you can override the dependency that calls that provider, and use a custom dependency that returns a mock user, only for your tests.

### Use the `app.dependency_overrides` attribute

## Security - HTTPS

In the [previous chapter about HTTPS](https.md){.internal-link target=_blank} we learned about how HTTPS provides encryption for your API.

We also saw that HTTPS is normally provided by a component **external** to your application server, a **TLS Termination Proxy**.

* **Modify some DNS records**.
    * For this, the renewal program needs to support the APIs of the DNS provider, so, depending on the DNS provider you are using, this might or might not be an option.
* **Run as a server** (at least during the certificate acquisition process) on the public IP address associated with the domain.

        use_sub_dependant = sub_dependant
        if (
            dependency_overrides_provider
            and dependency_overrides_provider.dependency_overrides
        ):
            original_call = sub_dependant.call
            call = getattr(
                dependency_overrides_provider, "dependency_overrides", {}
            ).get(original_call, original_call)

# Abhängigkeiten

**FastAPI** hat ein sehr mächtiges, aber intuitives **<abbr title="Dependency Injection – Einbringen von Abhängigkeiten: Auch bekannt als Komponenten, Ressourcen, Provider, Services, Injectables">Dependency Injection</abbr>** System.

Es ist so konzipiert, sehr einfach zu verwenden zu sein und es jedem Entwickler sehr leicht zu machen, andere Komponenten mit **FastAPI** zu integrieren.

## Was ist „Dependency Injection“

{!../../../docs_src/custom_docs_ui/tutorial001.py!}
```

!!! tip
    The *path operation* for `swagger_ui_redirect` is a helper for when you use OAuth2.

    If you integrate your API with an OAuth2 provider, you will be able to authenticate and come back to the API docs with the acquired credentials. And interact with it using the real OAuth2 authentication.

!!! tip
    Integrating other authentication/authorization providers like Google, Facebook, Twitter, GitHub, etc. is also possible and relatively easy.

    The most complex problem is building an authentication/authorization provider like those, but **FastAPI** gives you the tools to do it easily, while doing the heavy lifting for you.

## **FastAPI** utilities

开发人员永远都不需要直接调用这些函数，这些函数是由框架（在此为 **FastAPI** ）调用的。

通过依赖注入系统，只要告诉 **FastAPI** *路径操作函数* 还要「依赖」其他在*路径操作函数*之前执行的内容，**FastAPI** 就会执行函数代码，并「注入」函数返回的结果。

其他与「依赖注入」概念相同的术语为：

* 资源（Resource）
* 提供方（Provider）
* 服务（Service）
* 可注入（Injectable）
* 组件（Component）

## **FastAPI** 插件

**依赖注入**系统支持构建集成和「插件」。但实际上，FastAPI 根本**不需要创建「插件」**，因为使用依赖项可以声明不限数量的、可用于*路径操作函数*的集成与交互。

# Deploy FastAPI on Cloud Providers

You can use virtually **any cloud provider** to deploy your FastAPI application.

In most of the cases, the main cloud providers have guides to deploy FastAPI with them.

## Cloud Providers - Sponsors

Some cloud providers ✨ [**sponsor FastAPI**](../help-fastapi.md#sponsor-the-author){.internal-link target=_blank} ✨, this ensures the continued and healthy **development** of FastAPI and its **ecosystem**.

                solved_result = await solve_dependencies(
                    request=request,
                    dependant=dependant,
                    body=body,
                    dependency_overrides_provider=dependency_overrides_provider,
                    async_exit_stack=async_exit_stack,
                )
                values, errors, background_tasks, sub_response, _ = solved_result
                if not errors: