I don’t remember where, but I read a discussion about a library used in pdftk that was a problem in RHEL/CentOS 7. It seems that qpdf does many, if not more of the same things and is part of CentOS, no additional repo required. Here is the text from the description of the qpdf repo:
QPDF is a command-line program that does structural, content-preserving transformations on PDF files. It could have been called something like pdf-to-pdf. It includes support for merging and splitting PDFs and to manipulate the list of pages in a PDF file. It is not a PDF viewer or a program capable of converting PDF into other formats.
Naturally the syntax is different, but the times that I’ve needed it, qdf has been fine.