Using SASS and font-awesome with phoenix 1.6?

I am using dart_sass, and font awesome, it complains that there is a missing file

no route found for GET /webfonts/fa-solid-900.ttf

So I added the /webfonts through

cp -r assets/node_modules/@fortawesome/fontawesome-free/webfonts/ priv/static/

What is the right way of adding font-awesome and sass together