Environment conflicts with WickedPDF and Heroku - ruby-on-rails-3

Question

I am using WickedPDF, and I have basically two gems that include the binaries:
gem "wkhtmltopdf-heroku", "1.0.0"
gem "wkhtmltopdf-binary", "0.9.5.3"
The first one is supposed to be just for production, and the second one for development. The deployment to Heroku doesn't work if I have my Gemfile like:
group :development do
gem "wkhtmltopdf-binary", "0.9.5.3"
end
group :production do
gem "wkhtmltopdf-heroku", "1.0.0"
end
And it doesn't work either if I have it like:
group :production do
gem "wkhtmltopdf-heroku", "1.0.0"
end
It just works if I have it without groups. Just like:
gem "wkhtmltopdf-heroku", "1.0.0"
The error that I get is:
RuntimeError: Location of wkhtmltopdf unknown
Why would this happen? Why Heroku is not using the production group?

Answer 1

WickedPdf tries to figure out where the wkhtmltopdf binary lives, but can have a hard time on some systems (particularly shared servers).
You probably have to set it manually in an initializer something like this:
bin_location = case Rails.env
when 'production' then "/wherever/your/binary/is/bin/wkhtmltopdf"
when 'development' then "/local/path/to/wkthmltopdf"
else `which wkhtmltopdf`
end
WickedPdf.config = { :exe_path => bin_location }