Packaway
Packaway is a substitution server for the local Nix store.
It's essentially a reimplementation of nix-serve in Rust.
Packaway directly accesses the Nix database, and includes a Rust implementation of the NAR file format to maximize performance.
Setup
Add the flake github:danth/packaway to your server's configuration, and
import nixosModules.packaway from it.
Set services.packaway.enable to true to enable the service.
Generate a signing key by running
nix-store --generate-binary-cache-key your.host.name /path/to/secret/key /path/to/public/key,
then set services.packaway.secretKey to the path to the secret key.
Packaway runs on port 19082. You should either expose this port by adding it to
networking.firewall.allowedTCPPorts, or preferably use a reverse proxy to
serve it over HTTPS.
Once you've exposed the port, that's it! Rebuild the server and Packaway should be available.
On the client, add the public key you generated to
nix.settings.trusted-public-keys, and finally add http(s)://your.host.name/
to nix.settings.substituters.