variables - 如何在 Dockerfile 中定义变量？

Question

在我的 Dockerfile 中，我想定义以后可以在 Dockerfile 中使用的变量。

我知道 ENV 指令，但我不希望这些变量成为环境变量。

有没有办法在 Dockerfile 范围内声明变量？

Answer 1

您可以使用 ARG - 见 https://docs.docker.com/engine/reference/builder/#arg

The ARG instruction defines a variable that users can pass atbuild-time to the builder with the docker build command using the--build-arg <varname>=<value> flag. If a user specifies a buildargument that was not defined in the Dockerfile, the build outputs anerror.

Can be useful with COPY during build time (e.g. copying tag specific content like specific folders)For example:

ARG MODEL_TO_COPY
COPY application ./application
COPY $MODEL_TO_COPY ./application/$MODEL_TO_COPY

While building the container:

docker build --build-arg MODEL_TO_COPY=model_name -t <container>:<model_name specific tag> .