entrypoint

#!/bin/sh
set -e

createUser()
{
  USER=$1

  if ! id $USER > /dev/null 2>&1; then
    adduser -D $USER
    passwd -u $USER > /dev/null 2>&1
  fi

  mkdir -p /home/$USER/.ssh
  chmod 700 /home/$USER/.ssh
  chown $USER:$USER /home/$USER/.ssh
}

writeAuthorizedKeys()
{
  USER=$1
  AUTHORIZED_KEYS=$2

  echo "$AUTHORIZED_KEYS" > /home/$USER/.ssh/authorized_keys
  chown $USER:$USER /home/$USER/.ssh/authorized_keys
}

readEnvironment()
{
  for KEY in $(env | grep '^AUTHORIZED_KEYS_' | awk -F '\n' '{ print substr($0, 0, index($0, "=") - 1) }');
  do
    USER=$(echo $KEY | awk '{ gsub("AUTHORIZED_KEYS_", "", $1); print tolower($1) }')
    AUTHORIZED_KEYS=$(eval "echo \"\$$KEY\"")

    createUser $USER
    writeAuthorizedKeys $USER "$AUTHORIZED_KEYS"
  done
}

readFile()
{
  for KEY in /authorized_keys_*;
  do
    [ -e $KEY ] || break

    USER=$(echo $KEY | awk '{ gsub("/authorized_keys_", "", $1); print tolower($1) }')
    AUTHORIZED_KEYS=$(cat $KEY)

    createUser $USER
    writeAuthorizedKeys $USER "$AUTHORIZED_KEYS"
  done
}

readFile
readEnvironment

exec "$@"