How to unset “ENV” in dockerfile?

Question

For some certain reasons, I have to set \"http_proxy\" and \"https_proxy\" ENV in my dockerfile. I would like to now unset them because there are also some buil

Answer 1

If one needs env vars during the image build but they should not persist, just clear them. In the following example, the running container shows empty env vars.

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.sh

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 \
    .

run.sh

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

Output

no_proxy=
https_proxy=
http_proxy=
...