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。

创建依赖项非常简单、直观，并且还支持导入 Python 包。毫不夸张地说，只要几行代码就可以把需要的 Python 包与 API 函数集成在一起。

The dependency injection system requires pre-registration of the dependencies and the dependencies are solved based on the declared types. So, it's not possible to declare more than one "component" that provides a certain type.

* Caddy
    * Automatically handles certificates renewals ✨
* Nginx
    * With an external component like Certbot for certificate renewals
* HAProxy
    * With an external component like Certbot for certificate renewals
* Kubernetes with an Ingress Controller like Nginx
    * With an external component like cert-manager for certificate renewals
* Handled internally by a cloud provider as part of their services (read below 👇)

    * This SNI extension allows one single server (with a **single IP address**) to have **several HTTPS certificates** and serve **multiple HTTPS domains/applications**.
    * For this to work, a **single** component (program) running on the server, listening on the **public IP address**, must have **all the HTTPS certificates** in the server.
* **After** obtaining a secure connection, the communication protocol is **still HTTP**.

---

"_If anyone is looking to build a production Python API, I would highly recommend **FastAPI**. It is **beautifully designed**, **simple to use** and **highly scalable**, it has become a **key component** in our API first development strategy and is driving many automations and services such as our Virtual TAC Engineer._"

---

"_If anyone is looking to build a production Python API, I would highly recommend **FastAPI**. It is **beautifully designed**, **simple to use** and **highly scalable**, it has become a **key component** in our API first development strategy and is driving many automations and services such as our Virtual TAC Engineer._"

---

"_If anyone is looking to build a production Python API, I would highly recommend **FastAPI**. It is **beautifully designed**, **simple to use** and **highly scalable**, it has become a **key component** in our API first development strategy and is driving many automations and services such as our Virtual TAC Engineer._"

### Load Balancer

When using containers, you would normally have some component **listening on the main port**. It could possibly be another container that is also a **TLS Termination Proxy** to handle **HTTPS** or some similar tool.