Variable interpolation in CMD

Describe the bug Running a CMD with a command that uses an environment variable does not interpolate it. In package.json:

"scripts": {
  "storybook": "start-storybook -p ${STORYBOOK_PORT:-9001}",
}

In Dockerfile:

ENV STORYBOOK_PORT=300

CMD [ "/bin/sh", "-c", "npm run storybook" ]

OR

ENV STORYBOOK_PORT=3000

CMD [ "/bin/sh", "-c", "npm", "run", "storybook" ]

Results in $STORYBOOK_PORT always be an empty string.

[Schnitzel]

@alexdesignworks You can just change the CMD:

CMD [ "/bin/bash", "-c", "npm run storybook" ]

and then it’s running is bash

[Schnitzel]

plus the reason to now use bash by default is that bash is not by default in the alpine upstream images and we want to keep the images as small and as upstreamy as possible.