dockerfile set env variable code example

Example 1: docker how to echo env variable in bash

docker exec <container-name> env

Example 2: docker expose port

docker run -p [external]:[Internal]

#example (will open in localhost:8080 to container port 80)
docker run -p 8080:80

Example 3: dockerfile env variabes

FROM busybox
ENV foo /bar
WORKDIR ${foo}   # WORKDIR /bar
ADD . $foo       # ADD . /bar
COPY \$foo /quux # COPY $foo /quux