I have been trying to install pg to run my web application (Ruby on Rails).
I use a pg database.
With bundle install, it fails.
The output is:
current directory: /home/pi/.rvm/gems/ruby-2.3.3/gems/pg-0.18.4/ext /home/pi/.rvm/rubies/ruby-2.3.3/bin/ruby -r ./siteconf20161225-10359-1iu9cfy.rb extconf.rb checking for pg_config... no No pg_config... trying anyway. If building fails, please try again with --with-pg-config=/path/to/pg_config checking for libpq-fe.h... no Can't find the 'libpq-fe.h header *** extconf.rb failed *** Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers. Check the mkmf.log file for more details. You mayneed configuration options.
An error occurred while installing pg (0.18.4), and Bundler cannot continue. Make sure that `gem install pg -v '0.18.4'` succeeds before bundling.
What is the way to fix it?