env vars docker ENTRYPOINT

build.bash

#!/usr/bin/env bash

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

DOCKER_TAG="${DOCKER_TAG:-scratch0}"
cc="$(which ${CC:-x86_64-linux-musl-gcc})" # Choose any cross compiler, or just `gcc` if you're on a Linux box
cc_flags="${CC_FLAGS:--static}"
"$cc" "$DIR/env.c" -o "$DIR/env" -Wno-implicit-function-declaration "$cc_flags"
docker build --compress --force-rm --tag "$DOCKER_TAG"  .
docker run --rm "$DOCKER_TAG" -e FOO=bar
# PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
# HOSTNAME=eb77d24c5962
# HOME=/

Dockerfile

FROM scratch
COPY env /env
ENTRYPOINT ["/env"]

env.c

int main(int argc, char **argv, char** envp) { for(char** env=envp;*env!=0;env++) puts(*env, "\n"); }