如何在dockerfile中取消设置“ENV”？

Question

出于某些原因，我必须在我的dockerfile中设置“http_proxy”和“https_proxy”ENV。我想现在取消它们，因为还有一些构建过程无法通过代理完成。

# dockerfile

# ... some process

ENV http_proxy=http://...
ENV https_proxy=http://...

# ... some process that needs the proxy to finish

UNSET ENV http_proxy # how to I unset the proxy ENV here?
UNSET ENV https_proxy

# ... some process that can't use the proxy 

Answer 1

根据docker docs，您需要使用shell命令：

FROM alpine
RUN export ADMIN_USER="mark" \
&& echo $ADMIN_USER > ./mark \
&& unset ADMIN_USER
CMD sh

有关详细信息，请参阅https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#env。

Answer 2

如果在构建图像期间需要env vars但它们不应该持久存在，那么就清除它们。在以下示例中，正在运行的容器显示空的env变量。

Dockerfile

# set proxy
ARG http_proxy
ARG https_proxy
ARG no_proxy
ENV http_proxy=$http_proxy
ENV https_proxy=$http_proxy
ENV no_proxy=$no_proxy

# ... do stuff that needs the proxy during the build, like apt-get, curl, et al.

# unset proxy
ENV http_proxy=
ENV https_proxy=
ENV no_proxy=

build.是

docker build -t the-image \
    --build-arg http_proxy="$http_proxy" \
    --build-arg https_proxy="$http_proxy" \
    --build-arg no_proxy="$no_proxy" \
    --no-cache \
    .

润.是

docker run --rm -i \
    the-image \
    sh << COMMANDS
        env
COMMANDS

产量

no_proxy=
https_proxy=
http_proxy=
...

Answer 3

AFAIK，Dockerfile中没有声明本身支持此功能。但是，您可以使用普通的shell命令取消设置 -

...   
ENV http_proxy=http://...
RUN unset http_proxy
...