snapcraft requires optional VERSION_ID in os-release

[Miki Habryn]

Trying to build a snap on my Debian system fails with:

  File "/usr/lib/python3/dist-packages/snapcraft/internal/pluginhandler/__init__.py", line 770, in _find_dependencies
    dependencies += libraries.get_dependencies(elf_file)
  File "/usr/lib/python3/dist-packages/snapcraft/internal/libraries.py", line 100, in get_dependencies
    system_libs = _get_system_libs()
  File "/usr/lib/python3/dist-packages/snapcraft/internal/libraries.py", line 69, in _get_system_libs
    release = common.get_os_release_info()['VERSION_ID']
KeyError: 'VERSION_ID'
miki@slab:~/c/rtl_433$ uname -a
Linux slab 4.12.0-2-amd64 #1 SMP Debian 4.12.13-1 (2017-09-19) x86_64 GNU/Linux
miki@slab:~/c/rtl_433$

/etc/os-release does not contain a VERSION_ID. Adding one allows snapcraft to run successfully, however os-release(5) states that VERSION_ID is optional. Is there something else that this value could be defaulted to?

[Cris Dywan (kalikiana)]

The function _get_system_libs in snapcraft/internal/libraries.py uses VERSION_ID for the filename listing the .so files to exclude. I think the fix would be to treat no VERSION_ID the same as no file.

[Carlo Lobrano (c-lobrano)]

Hello, I'd like to work on this issue

[Kyle Fazzari (kyrofa)]

@Christian, what do you mean by treating it the same as no file? Which file? We don't account for /etc/os-release not being there at all.

[Kyle Fazzari (kyrofa)]

I think we just need to have reasonable backup plans for trying to determine distro. And use functions to do that rather than just accessing that dict everywhere.

[Cris Dywan (kalikiana)]

Sorry for being unclear. I meant the file libraries/16.04 - the code checks if libraries/$VERSION_ID exists and skips if it doesn't. So I was thinking if the property is not provided we could do the same.

[Kyle Fazzari (kyrofa)]

Nice job Carlo. I took it a step further here so that it starts working on e.g. Trusty: https://github.com/snapcore/snapcraft/pull/1636 .

[Carlo Lobrano (c-lobrano)]

Alright, I was trying myself, but I like your version better.