Switch from pdftk to pdfinfo

pdftk is no longer packaged for Alpine Linux and has an odd license.
pdfinfo is part of poppler which is licensed under GPL.

docker/Dockerfile

@@ -40,7 +40,7 @@ RUN install_packages \
     libcups2-dev \
     libcupsfilters-dev \
     # Needed to count pages in encrypted PDFs
-    pdftk \
+    poppler-utils \
     # Print uploads filetype detection
     shared-mime-info
 

docker/Dockerfile.alpine

@@ -31,7 +31,6 @@ RUN apk add --no-cache \
         imagemagick \
         imagemagick-perlmagick \
         mysql-client \
-        pdftk \
         perl-app-cpanminus \
         perl-dbd-mysql \
         perl-dev \
@@ -47,6 +46,7 @@ RUN apk add --no-cache \
         perl-params-validate \
         perl-posix-strftime-compiler \
         perl-yaml-xs \
+        poppler-utils \
         sed \
         shared-mime-info \
         wget

lib/Libki/Utils/Printing.pm

@@ -62,12 +62,11 @@ sub create_print_job_and_file {
             my $pdf = PDF::API2->open_scalar($pdf_string);
             $pages = $pdf->pages();
         }
-        catch { # PDF may be encrypted, try using pdftk instead
+        catch { # PDF may be encrypted, try using pdfinfo instead
             my ( $fh, $fn ) = tempfile();
             write_file( $fn, $pdf_string );
-            my $output = qx{ pdftk $fn dump_data | grep NumberOfPages };
-            $output =~ m/NumberOfPages: (\d+)/;
-            $pages = $1;
+            my $pages = qx{ pdfinfo $fn | awk '/^Pages:/ {print \$2}' };
+            chomp $pages;
         };
 
         my $printers = $c->get_printer_configuration;