bundle install fail without libpq-dev

[Patrick Hetu]

I got this error, but after installing libpq-dev the bundle install step finished.

Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /usr/bin/ruby1.9.1 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 may need configuration options.

Provided configuration options:
 --with-opt-dir
 --without-opt-dir
 --with-opt-include
 --without-opt-include=${opt-dir}/include
 --with-opt-lib
 --without-opt-lib=${opt-dir}/lib
 --with-make-prog
 --without-make-prog
 --srcdir=.
 --curdir
 --ruby=/usr/bin/ruby1.9.1
 --with-pg
 --without-pg
 --with-pg-dir
 --without-pg-dir
 --with-pg-include
 --without-pg-include=${pg-dir}/include
 --with-pg-lib
 --without-pg-lib=${pg-dir}/lib
 --with-pg-config
 --without-pg-config
 --with-pg_config
 --without-pg_config

Gem files will remain installed in /home/ubuntu/.bundler/tmp/24957/gems/pg-0.14.1 for inspection.
Results logged to /home/ubuntu/.bundler/tmp/24957/gems/pg-0.14.1/ext/gem_make.out
An error occurred while installing pg (0.14.1), and Bundler cannot continue.
Make sure that `gem install pg -v '0.14.1'` succeeds before bundling.