Following error is observed for bundle install step on macOS Mojave 10.14.6
An error occurred while installing pg (1.1.4), and Bundler cannot continue.
Make sure that `gem install pg -v '1.1.4' --source 'https://rubygems.org/'` succeeds before bundling.
The above error is caused when PostgreSQL server is not installed locally, which in the YBDB case is a normal case. The underlying error is Can't find the 'libpq-fe.h header.
Fixed the above by following instructions listed here: https://michaelrigart.be/install-pg-ruby-gem-without-postgresql/
$ brew install libpq
$ bundle config --local build.pg --with-opt-dir="/usr/local/opt/libpq"
$ bundle install