Failure to locate wkhtmltopdf binary in certain environments using bundler

[glossawy]

When upgrading our bundler version (we were running quite an old version in some environments, namely 1.10.x) we ran into an issue where apps using wicked_pdf would fail due to a failure to locate the wkhtmltopdf binary. We discovered this was because of changes introduced in bundler 1.14.x where a warning is output by bundler if the home directory is not writable/not found/etc., specifically by rubygems/bundler#4951.

This appears to be because of how wicked_pdf attempts to locate wkhtmltopdf, using the shell and executing which within the context of a bundle. In the right conditions this will pick up the warning output by bundler, which clearly leads to an invalid path.

Per pdfkit/pdfkit#388, you can observe the problem by doing the following:

# Set up gems with a real reference to wkhtmltopdf
gem install bundler --version 1.14.3
echo "source 'https://rubygems.org';\ngem 'wkhtmltopdf-binary-edge'" > Gemfile
bundle install --path vendor/bundle

# See the UI printout
HOME=/no/directory/found bundle exec which wkhtmltopdf

Leading to an output along the lines of

Your home directory is not set properly:
 * `/no/directory/found` is not a directory

Bundler will use `/var/folders/wj/q7cqmwds75z3ndcdxrmpd9gh0000gn/T/bundler/home/rdimarco` as your home directory temporarily

I have proposed a possible fix with associated tests at #728. Though there is a workaround, it may be worth it to not use bundle exec which wkhtmltopdf.

Workaround

The obvious workaround is to specify the binary path in WickedPdf.config per the readme.

[unixmonkey]

Closing since #728 was merged. Thanks!