Bug#1029066: diffoscope: FTBFS if no internet is available (using internet connection during build)

[FC Stegerman]

* Chris Lamb <lamby at debian.org> [2023-01-20 01:47]:
[...]
> As to a solution, though, I think this is somewhat blocking on Mattia's
> expertise in the generation of the Python test recommends. Are we, in
> essence, trying to parse the following data in setup.py?
> 
>     install_requires=[
>         "python-magic",
>         "libarchive-c",
>     ],
>     extras_require={
>         "distro_detection": ["distro"],
>         "cmdline": ["argcomplete", "progressbar"],
>         "comparators": [
>             "androguard",
>             "binwalk",
>             "defusedxml",
>             "guestfs",
>             "jsondiff",
>             "python-debian",
>             "pypdf",
>             "pyxattr",
>             "rpm-python",
>             "tlsh",
>         ],
>     },
> 
> If so, we don't necessarily have to wholesale move to pyproject.toml;
> instead, we could rejig setup.py...?

It seems that way.  And doing so via pep517, which uses pip to install
the requirements in a temporary environment, which I assume is why it
accesses the network sometimes (but not always): to install missing
requirements when the Debian package is not already installed on the
system.

I've proposed an MR [1] that moves the extras_require to a JSON file
and uses that from both setup.py and generate-recommends.py; I've
confirmed it produces the same debian/tests/control.tmp as before.

- FC

[1] https://salsa.debian.org/reproducible-builds/diffoscope/-/merge_requests/121