> For the complete documentation index, see [llms.txt](https://camelgemonion.gitbook.io/docker/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://camelgemonion.gitbook.io/docker/dockerfile-zhi-ling/parser-directives/syntax.md).

# syntax

```
# syntax=[remote image reference]
```

示例：

```
# syntax=docker/dockerfile
# syntax=docker/dockerfile:1.0
# syntax=docker.io/docker/dockerfile:1
# syntax=docker/dockerfile:1.0.0-experimental
# syntax=example.com/user/repo:tag@sha256:abcdef...
```

**仅当使用BuildKit后端时才启用此功能。**

**syntax指令**定义用于构建当前**Dockerfile**的**Dockerfile构建器**的位置。 **BuildKit**后端允许无缝使用构建器的外部实现，这些构建器以**Docker**镜像的形式分发并在容器沙箱环境中执行。

自定义**Dockerfile构建器**的实现将允许我们执行以下操作：

* 自动获取错误修正**(bugfixs)**，而无需更新守护进程
* 确保所有用户都使用相同的实现来构建**Dockerfile**
* 使用最新功能，而无需更新守护程序
* 试用新的实验性或第三方功能


---

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