【Docker】Dockerfile 之 COPY

参考教程：https://docs.docker.com/engine/reference/builder/

环境

1. virtual box 6.1
2. centos 7.8
3. docker 19.03

COPY

COPY has two forms:

COPY 指令有两种格式

COPY [--chown=<user>:<group>] <src>... <dest>
COPY [--chown=<user>:<group>] ["<src>",... "<dest>"]

This latter form is required for paths containing whitespace

包含空格的路径需要后一种形式

The COPY instruction copies new files or directories from <src> and adds them to the filesystem of the container at the path <dest>.

COPY 指令从 <src> 复制新文件或目录，并将它们添加到容器的文件系统中，路径为 <dest>。

Multiple <src> resources may be specified but the paths of files and directories will be interpreted as relative to the source of the context of the build.

可以指定多个 <src> 资源，但是文件和目录的路径将被解释为相对于构建上下文。

Each <src> may contain wildcards and matching will be done using Go’s filepath.Match rules. For example:

每个 <src> 可能包含通配符，并且匹配将使用 Go 的 filepath.Match 规则进行。例如：

To add all files starting with “hom”:

要添加所有以 “hom” 开头的文件：

COPY hom* /mydir/

In the example below, ? is replaced with any single character, e.g., “home.txt”.

在下面的示例中，? 被替换为任何单个字符，例如 “home.txt”。

COPY hom?.txt /mydir/

The <dest> is an absolute path, or a path relative to WORKDIR, into which the source will be copied inside the destination container.

<dest> 是绝对路径，或者是相对于 WORKDIR 的路径，源将被复制到目标容器内。

The example below uses a relative path, and adds “test.txt” to <WORKDIR>/relativeDir/:

下面的示例使用相对路径，并将 “test.txt” 添加到 <WORKDIR>/relativeDir/：

COPY test.txt relativeDir/

Whereas this example uses an absolute path, and adds “test.txt” to /absoluteDir/

而此示例使用了绝对路径，并将 “test.txt” 添加到 /absoluteDir/ 中

COPY test.txt /absoluteDir/

When copying files or directories that contain special characters (such as [ and ]), you need to escape those paths following the Golang rules to prevent them from being treated as a matching pattern. For example, to copy a file named arr[0].txt, use the following;

在添加包含特殊字符（例如 [ 和 ]）的文件或目录时，您需要按照 Golang 规则转义那些路径，以防止将它们视为匹配模式。例如，要添加名为 arr[0].txt 的文件，请使用以下命令；

COPY arr[[]0].txt /mydir/

Note

If you build using STDIN (docker build - < somefile), there is no build context, so COPY can’t be used.

注意

如果您使用 STDIN 进行构建（docker build - < somefile），则没有构建上下文，因此无法使用 COPY。

Optionally COPY accepts a flag --from=<name> that can be used to set the source location to a previous build stage (created with FROM .. AS <name>) that will be used instead of a build context sent by the user. In case a build stage with a specified name can’t be found an image with the same name is attempted to be used instead.

可选地，COPY 接受一个标志 --from=<name>，该标志可用于将源位置设置为先前的构建阶段（由 FROM .. AS <name> 创建），该标志将代替构建用户发送的上下文。如果找不到具有指定名称的构建阶段，则尝试改用具有相同名称的镜像。

COPY obeys the following rules:

COPY 遵守以下规则：

• The <src> path must be inside the context of the build; you cannot COPY ../something /something, because the first step of a docker build is to send the context directory (and subdirectories) to the docker daemon.

• <src> 路径必须在构建的上下文内部；您不能执行 COPY ../something /something，因为 docker build 的第一步是将上下文目录（和子目录）发送到 docker 守护进程。

• If <src> is a directory, the entire contents of the directory are copied, including filesystem metadata.

• 如果 <src> 是目录，则复制目录的整个内容，包括文件系统元数据。

Note

The directory itself is not copied, just its contents.

注意

目录本身不会被复制，只是其内容被复制。

• If <src> is any other kind of file, it is copied individually along with its metadata. In this case, if <dest> ends with a trailing slash /, it will be considered a directory and the contents of <src> will be written at <dest>/base(<src>).

• 如果 <src> 是任何其他类型的文件，则会将其及其元数据一起单独复制。在这种情况下，如果<dest> 以尾斜杠 / 结尾，则它将被视为目录，并且 <src> 的内容将被写在 <dest>/base(<src>) 中。

• If multiple <src> resources are specified, either directly or due to the use of a wildcard, then <dest> must be a directory, and it must end with a slash /.

• 如果直接或由于使用通配符而指定了多个 <src> 资源，则 <dest> 必须是目录，并且必须以斜杠 / 结束。

• If <dest> does not end with a trailing slash, it will be considered a regular file and the contents of <src> will be written at <dest>.

• 如果 <dest> 不以斜杠结尾，则将其视为常规文件，并且 <src> 的内容将被写入<dest>。

• If <dest> doesn’t exist, it is created along with all missing directories in its path.

• 如果 <dest> 不存在，则会与路径中所有缺少的目录一起创建它。

Note

The first encountered COPY instruction will invalidate the cache for all following instructions from the Dockerfile if the contents of <src> have changed. This includes invalidating the cache for RUN instructions. See the Dockerfile Best Practices guide – Leverage build cache for more information.

注意

如果 <src> 的内容已更改，则遇到的第一个 COPY 指令将使 Dockerfile 中所有以下指令的缓存无效。这包括使 RUN 指令的高速缓存无效。有关更多信息，请参见 Dockerfile 最佳实践指南-利用构建缓存。

示例

Dockerfile 文件

FROM busybox
COPY text2.txt /text2/

构建结果

[root@master env]# docker build -t jiangbo:0.0.1 .
Sending build context to Docker daemon  3.584kB
Step 1/2 : FROM busybox
 ---> dc3bacd8b5ea
Step 2/2 : COPY text2.txt /text2/
 ---> 072721a4c4d8
Successfully built 072721a4c4d8
Successfully tagged jiangbo:0.0.1

查看结果

[root@master env]# docker run -it jiangbo:0.0.1
/ # ls
bin    dev    etc    home   proc   root   sys    text2  tmp    usr    var
/ # ls t
text2/  tmp/
/ # ls text2/
text2.txt
/ #

总结

介绍了 Dockerfile 中 COPY 指令的使用。