TIL how to change Phoenix development server port
You can run your Phoenix dev server on a different port that tcp/4000.
# myapp/config/dev.exs
config :my_app, MyApp.Endpoint,
http: [port: System.get_env("PORT") || 4000],
Phoenix will use the ENV variable “PORT” if it exists. Otherwise it will fallback to tcp/4000. Then from the terminal
$ PORT=4003 mix phx.server
or
$ PORT=4003 iex -S mix phx.server
reference: Chris McCord’s answer on github
Tested on
elixir 1.4.4
phoenix 1.3.0
macOS Sierra 10.12.6