Docker check command

[oh6hay]

The docker check command reads a Dockerfile, checks each base image reference, and prints a message if any of the base images are not tagged at the latest checksum. Also, if not all images are tagged latest, the main executable returns a nonzero value (might be useful in a CI pipeline, for example):

#!/bin/bash
# this is a CI job
if dockpin docker check -f ./Dockerfile ; then
  echo maybe update your Dockerfile
fi
# ...