Docker container with entrypoint variable expansion and CMD parameters

Question

I want to create a Docker Image that acts as an executable for which the user passes a token as an environment variable. The executable has sub commands that the user should

Answer 1

As specified in the docker documentation, you are specifying an entrypoint that calls a shell (thus not in the shell form, but the exec one). The parameters are passed to the shell (and therefore ignored); only the command in the shell matters. You will see your issue solved after switching your entrypoint call to:

ENTRYPOINT ["usr/bin/mycmd", "--token=$MY_TOKEN"]

Calling a shell in an entrypoint is something heavily discouraged, and precisely only useful when you want to avoid users of the image append custom parameters to your entrypoint.

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