Bug: Issue with Liquid template in markdown caused by `markdown_inline_graphviz`

[joshbranham]

We are utilizing this plugin for our TechDocs generation for Backstage. We have a few markdown files with liquid templates nested in code blocks/fences, and they are being parsed as functions by what appears to be markdown_inline_graphviz per the below trace.

Example of a markdown block using this:

### Examples

```liquid
{% capture category %}{{ entity | property_value: 'Category' }}{% endcapture %}
{% if category == 'Pants' %}
  Resolution A
{% elsif category == 'Shoes' %}
  Resolution B
{% else %}
  Unknown
{% endif %}

Per the readme shouldn't this plugin be disabled unless I say to enable it?

markdown_inline_graphviz: A Python Markdown extension replaces inline Graphviz definitions with inline SVGs or PNGs. Activate the inline_graphviz extension using the usage instructions.

Our error:

verbose: [docker/mkdocs] ERROR - Error reading page 'public/guides/built-in-step-types.md': Command not supported: else verbose: [docker/mkdocs] Traceback (most recent call last): verbose: [docker/mkdocs] File "/usr/local/bin/mkdocs", line 8, in verbose: [docker/mkdocs] sys.exit(cli()) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/click/core.py", line 1130, in call verbose: [docker/mkdocs] return self.main(args, kwargs) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/click/core.py", line 1055, in main verbose: [docker/mkdocs] rv = self.invoke(ctx) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/click/core.py", line 1657, in invoke verbose: [docker/mkdocs] return _process_result(sub_ctx.command.invoke(sub_ctx)) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/click/core.py", line 1404, in invoke verbose: [docker/mkdocs] return ctx.invoke(self.callback, ctx.params) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/click/core.py", line 760, in invoke verbose: [docker/mkdocs] return __callback(args, kwargs) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/mkdocs/main.py", line 181, in serve_command verbose: [docker/mkdocs] serve.serve(dev_addr=dev_addr, livereload=livereload, watch=watch, kwargs) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/mkdocs/commands/serve.py", line 63, in serve verbose: [docker/mkdocs] config = builder() verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/mkdocs/commands/serve.py", line 58, in builder verbose: [docker/mkdocs] build(config, live_server=live_server, dirty=dirty) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/mkdocs/commands/build.py", line 292, in build verbose: [docker/mkdocs] _populate_page(file.page, config, files, dirty) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/mkdocs/commands/build.py", line 174, in _populate_page verbose: [docker/mkdocs] page.render(config, files) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/mkdocs/structure/pages.py", line 175, in render verbose: [docker/mkdocs] self.content = md.convert(self.markdown) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/markdown/core.py", line 261, in convert verbose: [docker/mkdocs] self.lines = prep.run(self.lines) verbose: [docker/mkdocs] File "/usr/local/lib/python3.8/site-packages/markdown_inline_graphviz.py", line 68, in run verbose: [docker/mkdocs] raise Exception('Command not supported: %s' % command) verbose: [docker/mkdocs] Exception: Command not supported: else

Our `mkdocs.yml`:

... plugins:

• techdocs-core

I opened this issue but I don't think it is a specific mkdocs issue https://github.com/mkdocs/mkdocs/issues/3067

Also of note, if I remove plugins from our config file and run npx @techdocs/cli serve -v the error goes away (although the resulting documentation is blank, which I imagine is due to removing all plugins.)

[joshbranham]

I can see here in the source we load the markdown_inline_graphviz plugin no matter what, which I think is the problem here. In our case we are not even using it, so being able to disable it would be helpful. Is there a path to do that?

https://github.com/backstage/mkdocs-techdocs-core/blob/c45280572c590e33ff5bbd82edede53830fdf9bb/src/core.py#L118

[joshbranham]

I can also see someone forked that plugin (https://github.com/cesaremorel/markdown-inline-graphviz) and changed it to use the following to denote an image instead of conflicting with Liquid/Jinja {% syntax. Anyway to use that instead of the other one?

```graphviz

[kunickiaj]

Running into the same issue here actually. The plugin version you linked is the one used here by techdocs-core. While it has the new syntax it does not disable the legacy (conflicting) syntax.

I haven't yet found a workaround and this is certainly a blocker for me atm.

[kunickiaj]

BTW, it seems this fork has continued some work and removed the legacy syntax so that it doesn't conflict.

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[Pike]

Bump

[robinselmer]

We are utilizing this plugin for our TechDocs generation for Backstage, too. When using Symfony Twig code like this

{% if areaname is defined and areaname is not empty %}
    ...
{% endif %}

it throws following error

verbose: [docker/mkdocs]   File "/usr/local/lib/python3.8/site-packages/markdown_inline_graphviz.py", line 68, in run
verbose: [docker/mkdocs]     raise Exception('Command not supported: %s' % command)
verbose: [docker/mkdocs] Exception: Command not supported: endif

[owenbush]

I was experiencing this same issue with twig template syntax, the way I managed to work around it was to just indent the twig markup inside of the code block.

```twig
{% if foo %}
  {{ foo }}
{% endif %}

I did 

  {% if foo %}
    {{ foo }}
  {% endif %}

[CasperGN]

Can only chime into the choir here that using standard mkdocs file:

site_name: 'Bifrost Docs'

exclude_docs: |
  documentation-templates/

plugins:
  - techdocs-core

the exclude is to NOT pick up the templates that are causing the rendering issue

I also observe that any liquid syntaxed markdown will throw an error on the keywords if, else, continue and so on. I've yet to find a way to make it not parse the liquid template but rather just render the markdown into html.

For now we circumvent it by excluding the template directory but I do see valid use-cases for liquid syntax'ed markdown being rendered without being parsed.

Should I open a separate issue on this matter?