How to install mupdf on heroku?

Question

I've upgraded to rails 5.2 and am implementing ActiveStorage. ActiveStorage uses mutool for PDF processing. I have successfully installed mutool locally using homebrew.

mutool is a bit confusing.  

rails docs claim to require "mutool", 
homebrew installs "mupdf-tools", 
and heroku wants "mupdf".

I have successfully installed apt and mupdf on heroku following these steps:

- add a new Aptfile to the root of my application with only "mupdf" listed
- commit and push the Aptfile
- THEN run heroku buildpacks:add --index 1 https://github.com/heroku/heroku-buildpack-apt
- push again so heroku will finish installing apt and mupdf

mupdf builds successful during the push

heroku buildpacks now returns    
1. https://github.com/heroku/heroku-buildpack-apt
2. heroku/ruby

If I refresh a page calling for a variant on a PDF, the image fails to process and the job kicks back the following error:

  Errno::ENOENT: No such file or directory - mutool

It seems mutool and mupdf are synonomous...so, I tried swapping out mutool for mupdf in my Aptfile...that failed to build from "...not found'.

Anyone know what action I need to take?

PS: This is part of implementing rails 5.2 using ActiveStorage.

UPDATE

I added mupdf-tools to Aptfile and that seems to fix the "no such file or directory" error. I don't know for sure because a new errors surfaces

MiniMagick::Invalid: `identify /tmp/mini_magick20180105-4-pvub9r` failed with error: identify.im6: no decode delegate for this image format `/tmp/mini_magick20180105-4-pvub9r' @ error/constitute.c/ReadImage/544.

MiniMagick::Error: `identify -format %m %w %h %b /tmp/ActiveStorage20180105-4-1f46tem[0]` failed with error: identify.im6: no decode delegate for this image format `/tmp/ActiveStorage20180105-4-1f46tem' @ error/constitute.c/ReadImage/544.

Answer 1

Heroku recommends Poppler as an alternative to MuPDF for licensing reasons (MuPDF has a commercial license).

They created a buildpack for Active Storage Previews that covers PDFs as well as Video files.

Answer 2

I know this is a bit old, but if you're still having this issue I was able to resolve this by updating the version of mupdf-tools to at least 1.8.

To do this with Heroku, you'll want to link directly to the latest release.

Add heroku-buildpack-apt, and then add a custom Aptfile. Note that you'll need to add the Aptfile first in order for the buildpack to work.

Here is what my Aptfile looks like:

:repo:deb http://archive.ubuntu.com/ubuntu artful main universe
imagemagick
ffmpeg
mupdf-tools

To test that you have the right version, you can use heroku ps:exec to test. Run mutool -v and you should be on version 1.11.