Building binaries

Single binary crates

If your Cargo.nix was generated for a single binary crate (i.e. workspace) then the derivation that builds your binary can be accessed via the rootCrate.build attribute. Use this command to build it and make the result available in the result directory:

your_crate_name="super_duper"
nix build -f Cargo.nix rootCrate.build
./result/bin/${your_crate_name}

Within a nix file (e.g. your manually written default.nix), you can access the derivation like this:

let cargo_nix = callPackage ./Cargo.nix {};
in cargo_nix.rootCrate.build

Cargo workspaces with multiple crates

If your Cargo.nix was generated for a workspace (i.e. not a single binary) then the derivation that builds your binary CANNOT be accessed via the rootCrate attribute. There is no single root crate.

Instead, you can conveniently access the derivations of all your workspace members through the workspaceMembers attribute. Use this command to build one of the workspace members and make the result available in the result directory:

your_crate_name="super_duper"
nix build -f Cargo.nix workspaceMembers.${your_crate_name}.build
./result/bin/${your_crate_name}

Within a nix file (e.g. your manually written default.nix), you can access the derivation like this:

let cargo_nix = callPackage ./Cargo.nix {};
in cargo_nix.workspaceMembers."${your_crate_name}".build