Pandoc on RHEL-8

Posted Sunday, Jan 16, 2022

#pandoc

Pandoc is a Haskell library for converting from one markup format to another, and a command-line tool that uses this library. It can convert from/to multiple formats including, but not limited to, various flavors of Markdown, HTML, LaTeX and Word docx and can produce PDF output.

Unfortunately pandoc is not available in Red Hat Enterprise Linux repos.

How to install

pandoc provides for different operatig systems including Linux. The Linux tarball is a statically linked binary and it has certain limitations (it can’t use LUA filters).

Installation is not rocket science. Go to https://github.com/jgm/pandoc/releases/latest, download the latest tarball (currently pandoc-2.17.0.1-linux-amd64.tar.gz) and run:

sudo tar xvzf pandoc-2.17.0.1-linux-amd64.tar.gz --strip-components 1 -C /usr/local/

You want to install TeX to be able to generate PDF output:

sudo yum -y install texlive

The TeX Live install is huge:

[...]
Transaction Summary
=======================================================================================
Install  227 Packages

Total download size: 356 M
Installed size: 607 M
Is this ok [y/N]: y
Downloading Packages:
[...]

Hello World!

Of course it works, producting nice PDFs:

pandoc hello.md -f markdown -t pdf -o hello.pdf

Eisvogel template

But bu may want to use fancy templates as Eisvogel, aimed at technical documents:

Go to https://github.com/Wandmalfarbe/pandoc-latex-template/releases/latest and download the latest version of the template (currently Eisvogel-2.0.0.tar.gz). Extract the needed file (there are lots of extra files that are not required) and move it to the local templates directory (usually ~/.pandoc/templates).

mkdir -p ~/.pandoc/templates
tar xf ~/Downloads/Eisvogel-2.0.0.tar.gz eisvogel.latex
mv eisvogel.latex ~/.pandoc/templates/

Ok, now we should be able to create a very nice pdf document based on that template:

$ pandoc pandoc-on-rhel-8.md -f markdown -s -t pdf -o pandoc-on-rhel-8.pdf --template eisvogel
Error producing PDF.
! LaTeX Error: File `footnotebackref.sty' not found.

Type X to quit or <RETURN> to proceed,
or enter new name. (Default extension: sty)

Enter file name: 
! Emergency stop.
<read *> 
         
l.99 \setlength

Meeeec. It seems some component is missing. Maybe we can install them from the repos:

$ yum search footnotebackref.sty
No matches found.

$ yum provides footnotebackref.sty
Error: No Matches found

Meeec.

Hmmm, maybe we did not install enough texlive packages. There are a few more:

$ sudo yum install texlive*
[sudo] password for user:
[...]
Transaction Summary
==========================================================================================
Install  124 Packages

Total download size: 128 M
Installed size: 197 M
Is this ok [y/N]: 
[...]

Meeec. Same error. Before continuing, I tried to edit the template and removing the missing package. It only led to another missing package. I commented it out. Removed it and… you guessed it, another missing dependency. And a lot more. No, that approach did not work.

The I decided to try to use the LaTeX Live Manager:

$ tlmgr install footnotebackref
*** WARNING ***: Performing this action will likely destroy the RHEL TeXLive install on your system.
*** WARNING ***: This is almost NEVER what you want to do.
*** WARNING ***: Try using dnf install/update instead.
*** WARNING ***: If performing this action is really what you want to do, pass the "ignore-warning" option.
*** WARNING ***: But please do not file any bugs with the OS Vendor.

Meeec. Sounds scary! And I don’t want to destroy my laptop! But… who cares? I will try to install all missing dependencies:

$ tlmgr install adjustbox babel-german background bidi collectbox csquotes everypage filehook footmisc footnotebackref framed fvextra letltxmacro ly1 mdframed mweights needspace pagecolor sourcecodepro sourcesanspro titling ucharcat ulem unicode-math upquote xecjk xurl zref --ignore-warning
You don't have permission to change the installation in any way,
specifically, the directory /usr/share/texlive/tlpkg/ is not writable.
Please run this program as administrator, or contact your local admin.
tlmgr: An error has occurred. See above messages. Exiting.

Meeec. No permissions? Who do you think you are?

$ sudo tlmgr install adjustbox babel-german background bidi collectbox csquotes everypage filehook footmisc footnotebackref framed fvextra letltxmacro ly1 mdframed mweights needspace pagecolor sourcecodepro sourcesanspro titling ucharcat ulem unicode-math upquote xecjk xurl zref --ignore-warning
[sudo] password for user: 
tlmgr: Remote repository is newer than local (2017 < 2018)
Cross release updates are only supported with
  update-tlmgr-latest(.sh/.exe) --update
Please see https://tug.org/texlive/upgrade.html for details.

The link above leads to some instructions that do not match the Red Hat installation.

Well, this is open source, we can still build everything from source.

Docker image to the rescue!

Ok, I give up. But there is still a chance. Pandoc offers not only several binaries for different operating systems, but also docker images, including some with LaTeX for PDF output. So go install podman (rootless/daemonless redhat-ish tool to run standalone (non-orchestrated) containers):

$ sudo yum install podman buildah skopeo

And test it:

podman run --rm --volume "`pwd`:/data" \
  --user `id -u`:`id -g` \
  pandoc/latex README.md \
  -o README.pdf

Cool, it works. But we still don’t have the nice Eisvogel template. But chances are that some invested some time in adding it to the pandoc official dockerfile. Turns out yes, it happened: Pandoc LaTeX with Eisvogel.

Just add the mydoc.yaml metadata and run the example command:

podman run --rm \
    -v `pwd`:/data \
    -w /data \
    rstropek/pandoc-latex \
    -f markdown \
    --template https://raw.githubusercontent.com/Wandmalfarbe/pandoc-latex-template/v1.4.0/eisvogel.tex \
    -t latex \
    -o mydoc.pdf \
    --metadata-file=mydoc.yaml \
    mydoc.md

It works! It needs a bit outdated template (the newest version is 2.0.0 and does not work) but that’s a start. I may update the post if I succeed updating the Dockerfile so that it works with the most recent template.