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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Python packaging tools can't resolve the package metadata without `libsystemd`","articleBody":"I ran into this whilst trying to move my project to replace `poetry` with `uv`.\n\nOne interesting property of `uv`, is that it creates a lockfile that works for all platforms. This means that even if `systemd-python` is only installed on Linux (`\"systemd-python\u003e=231; sys_platform == 'linux'\"` in the dependencies), it *needs* to be able to resolve the package metadata.\n\nThe problem is, as far as I can tell, `mesonpy` always run the meson build, even just for resolving the package metadata. And because the current meson build will hard-fail if libsystemd isn't available, regardless of the platform, it makes generating/updating the `uv` lockfile impossible on non-linux platforms.\n\n```\n❯ uv sync\n  × Failed to build `systemd-python==235`\n  ├─▶ The build backend returned an error\n  ╰─▶ Call to `setuptools.build_meta:__legacy__.build_wheel` failed (exit status: 1)\n\n      [stderr]\n      Cannot find libsystemd or libsystemd-journal:\n\n      Package libsystemd was not found in the pkg-config search path.\n      Perhaps you should add the directory containing `libsystemd.pc'\n      to the PKG_CONFIG_PATH environment variable\n      No package 'libsystemd' found\n\n      Package libsystemd-journal was not found in the pkg-config search path.\n      Perhaps you should add the directory containing `libsystemd-journal.pc'\n      to the PKG_CONFIG_PATH environment variable\n      No package 'libsystemd-journal' found\n\n\n      hint: This usually indicates a problem with the package or the build environment.\n  help: `systemd-python` (v235) was included because `matrix-synapse[systemd]` (v1.148.0rc1) depends on `systemd-python\u003e=231`\n```\n\nSome background about this issue on the mesonpy side can be read here: https://github.com/mesonbuild/meson-python/issues/236\n\nNow, this could be solved by making the C extension optional, and throw at runtime if it was built without it. It's not ideal, it would stop failing at build-time, but would make it possible to use `python-systemd` in projects using `uv` without requiring `libsystemd` to be available\n\nAnother very creative solution would be to write a special build backend which delegates to mesonpy in most cases, but provides its own `prepare_metadata_for_build_wheel` implementation… but that feels a bit overkill\n\nLast but not least, using another build backend than `mesonpy` could be a solution, but definitely more involved.\n\nI'll put up a draft PR for the first solution shortly to let you evaluate how that feels","author":{"url":"https://github.com/sandhose","@type":"Person","name":"sandhose"},"datePublished":"2026-02-20T16:25:50.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":16},"url":"https://github.com/167/python-systemd/issues/167"}