Pdf not loading using docker-compose

[goelinsights]

Brief Description

Trying to create derivative (thumbnails) of PDF with a multi-stage docker-compose setup. Getting "VipsForeignLoad: "/tmp/shrine20200904-1-13d7xwu.pdf" is not a known file format"

Expected behavior

Able to use ImageProcessing gem to load PDF and process JPEG thumbnails.

Actual behavior

Error loading the PDF

Traceback (most recent call last):
        2: from (irb):1
        1: from app/uploaders/brochure_uploader.rb:53:in `block in <class:BrochureUploader>'
Vips::Error (VipsForeignLoad: "/tmp/shrine20200904-1-13d7xwu.pdf" is not a known file format)
VipsForeignLoad: "/tmp/shrine20200904-1-13d7xwu.pdf" is not a known file format

Simplest self-contained example code to demonstrate issue

from brochure_uploader.rb
Attacher.derivatives do |original|
    vips = ImageProcessing::Vips.source(original)
    
    starter = vips.loader(page: 0).resize_to_fit(3000, nil).convert("jpeg")
    
 
    # generate the thumbnails you want here 
    { 
      thumb:  starter.saver(quality: 70).resize_to_limit!(150, 225),
      square_300_h: starter.saver(quality: 80).resize_to_fill!(300, 301),
      w_1000_h: starter.saver(quality: 80).resize_to_limit!(1000, nil),
      w_2500_h: starter.saver(quality: 90).resize_to_limit!(2500, nil),
    }
  end

and libraries loaded in the Dockerfile. I had thought that adding poppler would have supplied the necessary PDF file loading support, but it doesn't appear to work

# Stage Final
FROM ruby:2.6.3-alpine
RUN apk add --update --no-cache \
  bash \
  postgresql-client \
  vips \
  poppler-glib \
  tzdata \
  imagemagick \
  jpegoptim

System configuration

Ruby version: 2.6.3

Shrine version: 3.2.2

[janko]

Have you tried loading a PDF directly using ruby-vips? It's most likely not an issue with ImageProcessing gem, but ruby-vips/libvips itself, that it doesn't have PDF support. Personally I don't know what's exactly necessary in order to install libvips with PDF support, you'll have to find that out from the libvips maintainer or their installation guide.

Since this is not an issue with Shrine itself (ImageProcessing is a separate gem), I will close the issue.

[goelinsights]

If anyone comes across this in the future, I figured out that Vips doesn't install the PDF component (poppler) in a docker package and set configuration for PDF. Some licensing issue with GPL. You can either roll your own or use ImageMagick

Here's an example of how you can create a thumbnail jpeg of a PDF using "create_derivatives" in Shrine.

Attacher.derivatives do |original|
    orig = ImageProcessing::ImageMagick.source(original)
    starter = orig.loader(page: 1).convert("jpeg")
    # generate the thumbnails you want here 
    { 
      thumb:  starter.call,
      square_300_h: starter.saver(quality: 80).resize_to_fill!(300, 301),
      w_1000_h: starter.saver(quality: 80).resize_to_fit!(1000, nil)
    }
  end

The output from imagemagick is a bit lower quality than VIPS in my out of the box comparison on my machine, so if anyone figures out the right apt-get packages to get PDF recognition to turn on, would love to hear about it.

Relevant comments here:
libvips/php-vips-ext#31 (comment)