How to install binary Debian packages from github assets into the ReadTheDocs build environment?

Question

I have a python library that relies on a C library back-end that I'm trying to get into ReadTheDocs. There are Debian packages for the C library available in another git project.

I wrote the following script to fetch the latest version of the packages and install them:

#!/bin/sh
list=`
    curl -s "https://api.github.com/repos/scott-guthridge/libvna/releases/latest" |
        grep "browser_download_url" | cut -d '"' -f 4 |
    while read x; do
        case "$x" in
        *.deb)
            curl -L -O "$x"
            base=\`basename "$x"\`
            echo -n " ./$base"
            ;;
        *)
            ;;
        esac
    done`
echo "list: $list"
exec sudo apt install -y $list

I use this same script in the CI/CD process of yet another github project that relies on the same C library.

My .readthedocs.yaml script is:

version: 2
build:
  os: ubuntu-22.04
  tools:
    python: "3.11"
  apt_packages:
    - sudo
  jobs:
    pre_create_environment:
      - .github/scripts/install-libvna.sh

sphinx:
  configuration: docs/source/conf.py

where install-libvna.sh is the script above. In the ReadTheDocs build, the script runs and successfully fetches the Debian packages from github assets, but it then fails in the "sudo" command. Initially, sudo complained that there was no tty. I added the -S option to tell it to read the password from stdin (which is just EOF in this case) -- now it complains no password was given. I also tried removing the sudo and just running the "apt" command directly -- that complained that it wasn't running as root.

Debian packages can be installed through the apt_packages tag, but the packages for this library aren't (currently) available in any Linux distro. How can I get my prerequisite packages installed?

Answer 1

It appears that installing out of distro binary packages cannot currently be done in the ReadTheDocs build environment. First, the build.apt_packages section says that Personal Package Archives (PPA's) and other custom repositories are not supported. Next, the build.os section shows that the choice of build container is limited to two different versions of Ubuntu -- so creating a custom container with the library preinstalled also doesn't work. And as I already tried above, the custom build options, e.g. pre_system_environment and pre_create_environment, run with user permission (user "docs") that don't allow apt/dpkg commands to install.

I was able to get the library into the build a different way, though:

• In the post_system_dependencies, git clone the source for the library, build, and install into $HOME/.local
• In the ReadTheDocs GUI, add an environment variable: LD_LIBRARY_PATH=/home/docs/.local/lib
• Modify the package's build script to look for headers and libraries in ~/.local as well as the standard locations in the Cython build step.
• In the post_install step, pip install . to build the library.

With this, automodule is finally able to access the doc strings from the code. Working example is here.