Docker run --mount 在 RUN 期间使所有文件在不同的文件夹中可用 [英] Docker run --mount make all files available in a different folder during RUN

问题描述

我想在 RUN 语句期间使主机上的文件夹可用.也就是类似于用-v运行容器的效果:

I want to make a folder on my host machine available during a RUN statement. That is, similar to the effect of a container run with -v:

docker run -v /path/on/host:/path/in/container mycontainer:tag

在容器中，这给了我 /path/in/container 以及 path/on/host 中的所有文件/文件夹.

In the container this gives me /path/in/container with all files/folder in path/on/host.

为此，我正在尝试 https://github.com/moby/buildkit/blob/master/frontend/dockerfile/docs/experimental.md:

RUN --mount=type=bind,target=/path/on/host

这在 RUN 期间为我提供了一个文件夹 /path/on/host.

This gives me a folder /path/on/host during the RUN.

然后我有两个问题:

1. 我可以在 /path/on/host 中 ls 文件，但不能使用它们(例如 cat 它们).我尝试将 type 更改为例如cache 并使用 source 就像在 https://devops.stackexchange.com/questions/6078/in-a-dockerfile-is-there-a-way-to-avoid-copying-files-to-make-them-accessible-t，但我不能让它工作.

1. I can ls files inside /path/on/host, but not use them (e.g. cat them). I have tried changing type to e.g. cache and using source like in https://devops.stackexchange.com/questions/6078/in-a-dockerfile-is-there-a-way-to-avoid-copying-files-to-make-them-accessible-t, but I cannot make it work.

我不知道如何在RUN 图像"中使用不同的路径，即 /path/in/container 而不是 /path/on/host.

I cannot figure out how to have a different path inside the "RUN image", that is, /path/in/container instead of /path/on/host.

推荐答案

我想你误解了 RUN --mount=type=bind... 语法的用途.来自文档:

I think you have misunderstood what the RUN --mount=type=bind... syntax is for. From the documentation:

此挂载类型允许将上下文或映像中的目录(只读)绑定到构建容器.

This mount type allows binding directories (read-only) in the context or in an image to the build container.

换句话说，这不允许您在构建阶段访问任意主机目录.它不是类似于 docker run 上的 -v 命令行选项.它只允许您:

In other words, this does not permit you to access arbitrary host directories in the build stage. It is not an analog to the -v command line option on docker run. It only permits you to:

• 从构建上下文中挂载目录，或者
• 在多阶段构建中从另一个阶段装载目录

例如，我可以这样做，将目录从一个构建阶段安装到后续构建阶段:

So for example I can do this do mount a directory from one build stage into a subsequent build stage:

# syntax=docker/dockerfile:experimental

FROM centos AS centos

FROM alpine
RUN --mount=type=bind,from=centos,source=/,target=/centos ls /centos > /root/centos.txt

或者，如果我的构建上下文中有一个名为 example 的目录，我可以这样做以在构建过程中挂载它:

Or if I have a directory named example in my build context, I can do this to mount it during the build process:

# syntax=docker/dockerfile:experimental

FROM centos AS centos

FROM alpine
RUN --mount=type=bind,source=example,target=/data cp /data/* /root/

您正在使用的语法(未指定 from)...

The syntax you're using (with no from specified)...

RUN --mount=type=bind,target=/path/on/host

...只需将构建上下文的根目录安装在容器内的 /path/on/host 上.请记住，target 指定了容器内的安装点.例如，如果我的构建上下文如下所示:

...simply mounts the root of your build context on /path/on/host inside the container. Remember that target specifies the mountpoint inside the container. E.g., if my build context looks like this:

.
├── Dockerfile
└── example
    └── README.md

而example/README.md包含:

This is a test.

Dockerfile 包含一个 RUN 选项，类似于您正在使用的选项:

And the Dockerfile contains a RUN option similar to what you're using:

# syntax=docker/dockerfile:experimental

FROM centos AS centos

FROM alpine
RUN --mount=type=bind,target=/data cat /data/example/README.md > /root/README.md

那么当镜像构建完成后，/root/README.md就有了example/README.md的内容.

Then when the image is built, /root/README.md has the contents of example/README.md.

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