Add official lua-filters to pandoc images

[florian6973]

Following this discussion, it would be a great feature, especially for Github Actions, to add lua-filters to the Docker images, because filters like include-files are really useful. Thanks!

[cagix]

wouldn't it be easier and also more flexible to just add the desired filters as sub-module to your project and mount the folder inside the docker container?

[svenevs]

I'm in favor of adding them to the images to make things easier for users, but we'd need to deal with making sure root and non-root users can access them. This one may take time to iron out, this repo is currently in quasi-maintenance mode (thanks @tarleb ❤️).

That said, there are additional complications, specifically some of those filters need external tools we aren't installing. This may increase the size of the images here too much. At the very least, we can vendor the filters themselves and coordinate external tool installation documentation where applicable. Probably best documented in the lua-filters repo and linked to from here.

We should really start tagging releases here and on the lua-filters repo. Ref: #115, possible strategy:

1. Pandoc release finalized.
2. Any potential fixes to lua-filters (outstanding PR etc) resolved or put on hold, tag lua-filters repo.
3. Then we can release here vendoring the newly tagged filters.

[cannyboy]

Another vote for including lua filters, together with all the software requirements.

But really, I'd want a kitchen-sink version with everything, including the filter dependencies, old python filters too. And a few filters which are not in official filters, like mermaid. And the latex stuff.

A good use case is a high school student who wants to use text files and pandoc to produce all work, which might include diagrams, music notation, charts, math, flowcharts etc. They could use plain markdown for everything, but the install process for pandoc plus filters plus latex plus dependencies is a bit overwhelming.

[tarleb]

I think we'll need official releases of the Lua filters to be able to pack them easily and in a reproducible manner. I've made progress there, but it's not perfect yet.

A kitchen sink image is out of scope for us. You could take build your own by basing it on the lua-filters test image and extend it from there.

[tarleb]

There's a discussion on the lua-filters repo that might be relevant in this context: pandoc/lua-filters#207.

[caenrique]

any updates on including filters? having a mermaid filter would be awesome for using in in github actions to render diagrams