Rails pdf-extract gem has sqlite as dependency, but I'm using pg because Heroku requires it so bundle install fails

Question

I've been trying to install pdf-extract as a gem in my Rails app. When I go to build, I get this error because it uses sqlite as a dependency:

Fetching sqlite3 1.3.13
Installing sqlite3 1.3.13 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /home/vagrant/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/sqlite3-1.3.13/ext/sqlite3
/home/vagrant/.rbenv/versions/2.3.0/bin/ruby -r ./siteconf20180425-3298-14ft47q.rb extconf.rb
checking for sqlite3.h... no
sqlite3.h is missing. Try 'brew install sqlite3',
'yum install sqlite-devel' or 'apt-get install libsqlite3-dev'
and check your shared library search path (the
location where your sqlite3 shared library is located).
*** 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/vagrant/.rbenv/versions/2.3.0/bin/$(RUBY_BASE_NAME)
    --with-sqlite3-config
    --without-sqlite3-config
    --with-pkg-config
    --without-pkg-config
    --with-sqlite3-dir
    --without-sqlite3-dir
    --with-sqlite3-include
    --without-sqlite3-include=${sqlite3-dir}/include
    --with-sqlite3-lib
    --without-sqlite3-lib=${sqlite3-dir}/lib

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

  /home/vagrant/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/extensions/x86_64-linux/2.3.0-static/sqlite3-1.3.13/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /home/vagrant/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/sqlite3-1.3.13 for inspection.
Results logged to /home/vagrant/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/extensions/x86_64-linux/2.3.0-static/sqlite3-1.3.13/gem_make.out

An error occurred while installing sqlite3 (1.3.13), and Bundler cannot continue.
Make sure that `gem install sqlite3 -v '1.3.13'` succeeds before bundling.

In Gemfile:
  pdf-extract was resolved to 0.1.1, which depends on
    sqlite3

Is there anyway I can still use pdf-extract? Heroku doesn't allow sqlite in production.

Any help is greatly appreciated.

EDIT:

For those who encounter this issue in the future: I attempted to hack the gem to get it to work with postgres--this seemed to work though it caused the gem's performance to tank. Ultimately, I created an entirely separate api-only app, deployed directly to AWS using Elastic Beanstalk rather than through Heroku so that app could use sqlite3, and called the api-app to implement the gem functionality in my original app.

This approach would likely work well for any gems that cause dependency issues in a preexisting Rails app.

Answer 1

There is no way to use a gem that has a dependency if you cannot install that dependency. Your options are to

• Use a different PDF Gem
• Use an alternative to Heroku
• Find a way to implement the functionality you need from Pdf-extract yourself without using any gems
• Go through the gem's code to see where it uses sqlite and try to get rid of that code without breaking the gem

Answer 2

I would save yourself the time and trouble involved with getting this to work and look at alternative libraries. There is a PDF text extraction gem called HyPDF that is also a Heroku add-on .