Python’s builders have accepted a proposal to create a universal lock file format for Python projects that would specify dependencies, enabling installation reproducibility in a Python environment.
Python Enhancement Proposal (PEP) 751, accepted March 31, aims to create a new file format for specifying dependencies that is machine-generated and human-readable. Installers consuming the file should be able to calculate what to install without needing dependency resolution at install-time, according to the proposal.
Currently no standard exists to create an immutable record, such as a lock file, that specifies what direct and indirect dependencies should be installed into a Python virtual environment, the proposal states. There have been at least five well-known solutions to the problem in the community, including PDM, pip freeze, pip-tools, Poetry, and uv, but these tools vary in what locking scenarios are supported. ”By not having compatibility and interoperability it fractures tooling around lock files where both users and tools have to choose what lock file format to use upfront, making it costly to use/switch to other formats,” the proposal says.
