Operations
===

Deploying NixOS machines
---

Machine configurations are in `ops/machines.nix`.

Wrapper script to show all available machines and provision a single machine:

     $ $(nix-build -A ops.provision)
     Available machines:
      - bc01n01.hswaw.net
      - bc01n02.hswaw.net
      - dcr01s22.hswaw.net
      - dcr01s24.hswaw.net
      - edge01.waw.bgp.wtf

     $ $(nix-build -A ops.provision) edge01.waw.bgp.wtf

This can be slow, as it evaluates/builds all machines' configs. If you just want to deploy one machine and possible iterate faster:

    $ $(nix-build -A 'ops.machines."edge01.waw.bgp.wtf".config.passthru.hscloud.provision')

Remote Builders (cross-compiling)
---

If you're attempting to deploy a machine which has a system architecture other
than your host machine (eg. are deploying an Aarch64 Raspberry Pi4 from an
Intel machine), you'll need to use a remote builder which has that target
architecture.

Any machine of that target architecture running Nix(OS) will do, even the
machine you're deploing. But we also have some dedicated build machines:

| Name                    | Architecture | CPUs | RAM   |
|-------------------------|--------------|------|-------|
| larrythebuilder.q3k.org |      AArch64 |    4 | 24GiB |

To use a machine `$name` as a remote builder:

1. Make sure you have access to the machine. `ssh $username@$name` should work. If not, file a CR to get your key added to the machine and ask someone to review and deploy it. The machines' key confiurations are in hscloud.

2. Check `nix store ping --store ssh-ng://$username@$name`. It should work.

3. On NixOS, configure builders in your system configuration.nix and rebuild, eg.:

```
nix.buildMachines = [
  {
    system = "aarch64-linux";
    sshUser = "root";
    sshKey = "/home/q3k/.ssh/id_ed25519";
    maxJobs = 4;
    hostName = "larrythebuilder.q3k.org";
  }
];
nix.distributedBuilds = true;
```

4. On non-NixOS, configure builders in your nix.conf, eg. `builders = ssh://$username@$name aarch64-linux` in your system/user nix.conf. Your nix-daemon should also specify that the local user is trusted.

We should automate this some day.