Read pdf file with php-imagick on Travis

I need to read a pdf file on Travis with php-imagick extension.

I learned i need to adjust imagick policy.xml file to allow imagick to read pdf files. So i added a custom policy.xml.

env:
  global:
     - MAGICK_CONFIGURE_PATH=$HOME/.config/ImageMagick/
...
before_script:
    # Allow imagemagick to read PDF files
    - echo $MAGICK_CONFIGURE_PATH
    - mkdir $MAGICK_CONFIGURE_PATH
    - echo '<policymap>' > $MAGICK_CONFIGURE_PATH/policy.xml
    - echo '<policy domain="coder" rights="read" pattern="PDF" />' >> $MAGICK_CONFIGURE_PATH/policy.xml
    - echo '</policymap>' >> $MAGICK_CONFIGURE_PATH/policy.xml
    - sudo rm /etc/ImageMagick-6/policy.xml

but still the build fails with [Failed to read the file]

The file is there, locally it works, i suspect that imagick still cant read PDFs. The new policy also seems to be applied:

$convert -list policy

Path: /home/travis/.config/ImageMagick/policy.xml
  Policy: Coder
    rights: Read 
    pattern: PDF
  Policy: Coder
    rights: Read 
    pattern: PDF
Path: [built-in]
  Policy: Undefined
    rights: None

How can i fix this?

Failed build is: https://travis-ci.org/ivoba/silverstripe-simple-pdf-preview/jobs/563919021

Solution

After a while i just answer my own question:

The problem was that imagemagick needs ghostscript for working with pdfs and ghostscript needs to be installed in Debian.

So additionally to editing the policy.xml file, adding the install command to .travis.yml did the trick.

sudo apt-get install -y ghostscript

Full working travis file is: https://github.com/ivoba/silverstripe-simple-pdf-preview/blob/master/.travis.yml