gem install rails rails new Project --database=postgresql -T rails new api --api --database=postgresql -T rails new -j webpack hello-rails-react --database=postgresql -T rails server //You have to go into your config/database.yml, and change the following configurations. default: &default adapter: postgresql encoding: unicode user: postgres password: password pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %> development: <<: *default database: hellorails_development user: postgres password: password test: <<: *default database: hellorails_test user: postgres password: password production: <<: *default database: hellorails_production username: hellorails password: <%= ENV["HELLORAILS_DATABASE_PASSWORD"] %>