entrypoint

#!/bin/bash
set -euo pipefail

if [[ $# -eq 0 ]]; then
    # If the container is run with no arguments, then print a message and exit.
    cut -c 9- <<<"
        This is the Nextstrain pathogen build container.  It has a complete
        Nextstrain environment installed which is normally accessed via the
        \`nextstrain\` command on your computer (not in the container).
        
        If you're seeing this message though, you're probably not using the
        \`nextstrain\` command.  Welcome!  :-)
        
        The default container entrypoint will exec a command-line of your
        choosing in the build environment.  You can use this functionality to
        debug or develop Nextstrain pathogen builds and components.  Refer to
        the source of the \`nextstrain\` command for examples.
    "
else
    # Otherwise, exec into whatever command is provided…
    if [[ "$(id -u):$(id -g)" == 0:0 ]]; then
        # …switching to nextstrain:nextstrain first if we're root.
        exec setpriv --reuid nextstrain --regid nextstrain --init-groups "$@"
    else
        exec "$@"
    fi
fi