These are the notes from working through the new version of the book.
Firstly Phoenix 1.4 has been released so the Phoenix install instructions are out of date so here is the update:
$ mix archive.uninstall phx_new
$ mix archive.install hex phx_new 1.4.0
(from: https://phoenixframework.org/blog/phoenix-1-4-0-released)
I also did not have postgres installed:
$ brew install postgres
initdb /usr/local/var/postgres
/usr/local/opt/postgres/bin/createuser -s postgres
(from https://stackoverflow.com/questions/15301826/psql-fatal-role-postgres-does-not-exist)
This will get you to the end of the hello app.
Developer Rants 