Using cargo offline with apt packages

To instruct cargo to use only dependencies you've locally installed with apt instead of those on crates.io, set up your .cargo/config.toml file like this. For example, the one in your home directory /home/user/.cargo/config.toml.

[net]
offline = true

[source]

[source.apt]
directory = "/usr/share/cargo/registry"

[source.crates-io]
replace-with = "apt"

Why though?

See the blog post which prompted this: Rust without crates.io