What Is Cargo.lock and Should I Commit It?

Yes, you should always commit Cargo.lock to your version control system for binary applications to ensure reproducible builds across all environments. This file locks your dependencies to exact versions, preventing unexpected breakage when team members or CI systems install different versions of the same crate. Add the file to your repository immediately if it is missing by running the following command:

git add Cargo.lock
git commit -m "Add Cargo.lock for reproducible builds"

Note: If you are developing a library crate (a project meant to be published to Crates.io), you should generally exclude Cargo.lock from version control, as the library's consumers will generate their own lock files based on their specific dependency trees.

Cargo.lock is a file that records the exact versions of every external tool your project uses, ensuring everyone builds the software with the same ingredients. Think of it like a detailed recipe card that lists specific brand names and batch numbers for every ingredient, so the dish tastes exactly the same no matter who cooks it. You commit this file to your project so that your team and automated servers don't accidentally use outdated or incompatible versions of tools.