PG gem won't install in Rails app: Gem::Ext::BuildError: ERROR: Failed to build gem native extension

Question

I'm trying to deploy my Rails app to Heroku and when I add the pg gem to my gemfile and run bundle install I get an error:

An error occurred while installing pg (1.1.3), and Bundler cannot continue.
Make sure that `gem install pg -v '1.1.3'` succeeds before bundling.

The bottom of my gemfile looks like this:

group :development do
  # Access an IRB console on exception pages or by using <%= console %> anywhere in the code.
  gem 'web-console', '>= 3.3.0'
  gem 'listen', '>= 3.0.5', '< 3.2'
  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
  gem 'spring-watcher-listen', '~> 2.0.0'
  # Use sqlite3 as the database for Active Record
  gem 'sqlite3'
end

group :production do
  gem 'pg'
end

When I run gem install pg I get the following:

ERROR:  Error installing pg:
        ERROR: Failed to build gem native extension.

    current directory: /home/scott_imunro/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/pg-1.1.3/ext
/home/scott_imunro/.rbenv/versions/2.4.2/bin/ruby -r ./siteconf20181115-1119-1gb3plu.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 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=/home/scott_imunro/.rbenv/versions/2.4.2/bin/$(RUBY_BASE_NAME)
        --with-pg
        --without-pg
        --enable-windows-cross
        --disable-windows-cross
        --with-pg-config
        --without-pg-config
        --with-pg_config
        --without-pg_config
        --with-pg-dir
        --without-pg-dir
        --with-pg-include
        --without-pg-include=${pg-dir}/include
        --with-pg-lib
        --without-pg-lib=${pg-dir}/lib

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /home/scott_imunro/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/extensions/x86_64-linux/2.4.0-static/pg-1.1.3/mkmf.log

extconf failed, exit code 1

I'm running Rails 5 with an Ubuntu bash for Windows 10. Any ideas how to resolve this error?

Answer 1

This will likely be due to missing dependencies. Run the command manually in the terminal gem install pg -v '1.1.3' see what output you get.

You're likely missing the pre-requisite libs/headers for the gem. Try:

sudo apt-get update
sudo apt-get install git-core curl zlib1g-dev build-essential libssl-dev libreadline-dev libyaml-dev libsqlite3-dev sqlite3 libxml2-dev libxslt1-dev libcurl4-openssl-dev python-software-properties libffi-dev postgresql-client-common postgresql-client libpq-dev

Might be worth having a look over this article: https://medium.com/@colinrubbert/installing-ruby-on-rails-in-windows-10-w-bash-postgresql-e48e55954fbf