Comment by mh-cx

Exactly this. In our case we went so far to cache all static assets. Putting them into a directory with a hash in the name made them still easy to bust.

  # Cache static files
  location ~* \.(ico|css|js|gif|jpe?g|png|svg|woff|woff2)$ {
    expires 365d;
    add_header Pragma public;
    add_header Cache-Control "public";
    proxy_pass http://127.0.0.1:9000;
  }