Support env_file

[dhulihan]

This would be a killer feature for container-transform.

[dhulihan]

Nice! Good progress, but PR #50 omits env-file from ECS when provided (since ECS doesn't support env-file in task definitions, totally understandable). What do you think about reading in env-file and converting line entries to environment members?

[micahhausler]

I'd rather not enable unsupported features, add as few surprises as possible, and keep the tool simple to maintain and understand.

While it is a manual step, you could still script the dumping an env file to your compose:

cat <<EOF >app.env
TERM=xterm
CT_INPUT_TYPE=compose
CT_OUTPUT_TYPE=ecs
EOF
cat app.env | sed -e 's/=/: /g' >> docker-compose.yml

[dhulihan]

No worries, thanks for the consideration and snippet.