remove_unused_modules.sh

#!/bin/bash
set -e

IN_USE=$(mktemp)
ALL_FILES=$(mktemp)

function find_module() {

  dir=$(realpath $1)

  find "$dir" -maxdepth 1 -type f -name '*.tf' | while read file; do
    echo "${file}" >>$IN_USE

    grep -o "\s*source\s*=.*" $file | grep -v git | awk '{print $3}' | sed 's/"//g' | while read module; do

      if [ -d "${1}/${module}" ]; then
        find_module "${1}/${module}"
      fi

    done
  done

}

find workspaces -mindepth 2 -maxdepth 2 -type d | while read workspace; do

  find_module $workspace

done

find . -mindepth 2 -type f -name '*.tf' | grep -v ".terraform" | xargs realpath | sort | uniq >$ALL_FILES

comm <(cat $IN_USE | xargs realpath | sort | uniq) $ALL_FILES -3 | sort | sed 's/	//' | uniq | xargs -I % dirname % | uniq | xargs -I % rm -rf %

rm -rf $IN_USER $ALL_FILES