Run packer docker image interactively

Probably a simple docker thing I am overlooking as I am a bit green with docker…

How does one run the official hashicorp/packer interactively with a basic shell? Trying a vanilla docker run -it imageid doesnt work nor appending a /bin/sh to try and get a basic shell to poke around. Trying to run with a long sleep (to keep container running) and then docker exec to run some basic commands also wont work.

The hashicorp/packer image will always simple run a packer command passing back the menu of packer args.

Trying to hit the alpine shell to run some basic commands, add in some foo for ansible and other bits.

Feeling silly as its a simple entrypoint arg:

# get interactive
docker run --entrypoint /bin/ash -it <packerid>

#pass command to entrypoint to run
docker run --entrypoint /bin/ash it <packerid> -c "printenv"