machines.barnacle: join retiolum
barnacle is the first node on kartei darwinModules.retiolum: 2configs/retiolum.nix
is built on nixpkgs services.tinc, systemd-networkd and networking.firewall,
none of which exist on nix-darwin.
Host data (addresses, aliases, peer host files) comes from lass/hosts/barnacle
in kartei; the NixOS machines still read their host data through stockholm and
will not route to barnacle until that kartei pin is bumped.
The Ed25519 keypair is a clan var like on the NixOS nodes, but deployed with
neededFor = "activation": clans /run/secrets installer is Linux-only (tmpfs +
move-mount). No RSA half, tincr is SPTPS/Ed25519-only.