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 at build-time to the builder with the docker build command using the --build-arg <varname>=<value> flag. If a user specifies a build argument that was not defined in the Dockerfile, the build outputs an error.

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> .