Build Modes

Choose where the Nix closure is built: locally on the machine running Panix (default), or remotely on the installable’s first machine.

Local Mode (Default)

Builds run on the machine executing Panix:

nix build --no-link --print-out-paths --keep-going <flake-url>#<installable>

Panix also passes the experimental features flags and any configured nix command flags; the same applies to the remote command below. The closure is then transferred to each target machine via nix copy. Machines whose hostname matches local_machine_hostname skip the transfer entirely: they share the local store.

Remote Mode

Builds run on the installable’s first machine via the Nix remote store protocol:

nix build --eval-store auto --store ssh-ng://<first-machine> --option builders "" --no-link --print-out-paths --keep-going <flake-url>#<installable>

Use remote mode when:

The target machine has more resources (CPU/RAM) than the machine running Panix
The machine running Panix and the targets are not the same architecture

Configuration

fleet:
  flakes:
    my-flake:
      url: <url>
      installables:
        nixosConfigurations:
          my-server:
            nix:
              build_mode: remote
            machines:
              builder-and-target:   # first machine: remote builder and target
                ssh:
                  hostname: 192.168.1.100
              target-2:             # closure copied from builder-and-target
                ssh:
                  hostname: 192.168.1.101

build_mode can be set at fleet, flake, or installable level, inherited like other nix options. It cannot be set at machine level, since build is a per-installable phase shared by the installable’s machines.

Advanced Distributed Builds

For advanced distributed builds: