rp3: Build and deploy with Cachix Deploy

* Install QEMU static binaries so we can aarch64 images
* Configure Nix to build for aarch64 with emulation
* Install cachix-agent on rp3

.github/workflows/build-and-deploy.yml

@@ -18,9 +18,11 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
+      - uses: docker/setup-qemu-action@v3
       - uses: cachix/install-nix-action@v23
         with:
           nix_path: nixpkgs=channel:nixos-unstable
+          extra_nix_config: "extra-platforms = aarch64-linux"
       - uses: cachix/cachix-action@v12
         with:
           name: wagdav

flake.nix

@@ -78,6 +78,7 @@
           agents = {
             nuc = self.nixosConfigurations.nuc.config.system.build.toplevel;
             x230 = self.nixosConfigurations.x230.config.system.build.toplevel;
+            rp3 = self.nixosConfigurations.rp3.config.system.build.toplevel;
           };
         };
       };

host-rp3.nix

@@ -4,6 +4,7 @@
   imports = [
     ./hardware/rp3.nix
     ./modules/common.nix
+    ./modules/cachix.nix
     ./modules/remote-builder
     ./modules/consul/client.nix
   ];