To resolve AWS EMR hostnames from your MacOS machine you'll need to install and configure dnsmasq:
brew install dnsmasq
Add the following to /usr/local/etc/dnsmasq.conf
# configure resolution of AWS EMR hostnames
address=/eu-west-1.compute.internal/127.0.0.1
synth-domain=eu-west-1.compute.internal,0.0.0.0,255.255.255.255,ip-