Rust’s Cargo and .lock Files in Package Managers

I’m finding the various Rust guides well written — or perhaps just well written for me. This bit in the Cargo Guide (Rust’s package manager and build tool) on Cargo.lock files was particularly succinct.

If you’re building a non-end product, such as a rust library that other rust packages will depend on, put Cargo.lock in your .gitignore. If you’re building an end product, […] like a command-line tool or an application, or a system library with crate-type of staticlib or cdylib, check Cargo.lock into git. If you’re curious about why that is, see “Why do binaries have Cargo.lock in version control, but not libraries?” in the FAQ.

I remember learning about package manager .lock files for composer and npm, and most of what was written about them was selling you on a particular use case.

This is why you must use .lock files_

or

Using a .lock file? Here’s 10 reasons you’re history’s greatest a monster

The Rust docs are great here because they lay out simple rules for a beginner to follow, but then back that rule up more in-depth documentation elsewhere.