using configuration file results in builder without graphviz

[rokroskar]

Our project contains graphviz directives and uses the sphinx graphviz extension. This has worked very well for years on RTD. A few days ago we added a .readthedocs.yaml file:

version: 2
build:
  os: ubuntu-20.04
  tools:
    python: "3.9"

sphinx:
  configuration: docs/conf.py

python:
  install:
  - requirements: docs/requirements.txt

submodules:
  include: all

If this file is in the project, dot is not found and the graphviz graphs don't render. I assume this is a problem with the builder since I can't find any place to state that graphviz should be installed/used.

[stsewd]

Can you share your rtd project and repo?

[rokroskar]

sure, sorry for omitting that...

This is a build of master that doesn't find dot: https://readthedocs.org/projects/renku/builds/15244844/
And here's a build where I removed the .readthedocs.yaml file: https://readthedocs.org/projects/renku/builds/15247371/

The repo is here: https://github.com/SwissDataScienceCenter/renku

[humitos]

I found this in the logs:

generating indices... WARNING: dot command 'dot' cannot be run (needed for graphviz output), check the graphviz_dot setting

Doesn't graphviz require an APT package to be installed to be able to render properly? Maybe graphviz. You can use https://docs.readthedocs.io/en/stable/config-file/v2.html#build-apt-packages to install it.

Please, take a look at that and let me know.

[stsewd]

There are two things I see different:

• the python version: 3.7 vs 3.9
• Submodules aren't being cloned recursively https://docs.readthedocs.io/en/stable/config-file/v2.html#submodules

But I think the main problem is the base image used in the builds, the old image has https://github.com/readthedocs/readthedocs-docker-images/blob/6e61b2a903a0a22d2c14bec5f55b01467c39fbda/Dockerfile#L23 pre-installed. You need to install the apt package graphviz or graphviz-dev https://docs.readthedocs.io/en/stable/config-file/v2.html#build-apt-packages.

[rokroskar]

Ah you're absolutely right @humitos and @stsewd, I totally missed that in the docs 🤦 Apologies for the noise.

What I found confusing was this line in the FAQ:

We can’t support installing random C binaries on our system, so there is another way to fix these imports.

which led me to believe that I couldn't install additional packages beyond what was already in the builder images (and I completely missed the apt part in the configuration file docs).

I added a short blurb to the FAQ here: #8676