README.md

@@ -9,38 +9,28 @@ Machines are configured to act as build servers / binary caches for each other i
 ### Onboarding a device as a build client
 
 1. Generate a key pair on the device:
-
-   ```sh
-   sudo ssh-keygen -t ed25519 -f /etc/nix/distributed-build-key -N "" -C "$(hostname)-nix-builds" && sudo cat /etc/nix/distributed-build-key.pub
    ```
-
+   sudo ssh-keygen -t ed25519 -f /etc/nix/distributed-build-key -N "" -C "$(hostname)-nix-builds"
+   ```
 2. Add the public key to the device entry in `devices.nix`:
-
    ```nix
    distributedBuilds.clientPublicKey = "ssh-ed25519 AAAA... <hostname>-nix-builds";
    ```
-
 3. Rebuild all build machines so they pick up the new authorized key.
 
 ### Adding a build server
 
 1. Add to its entry in `devices.nix`:
-
    ```nix
    distributedBuilds.isBuilder = true;
-   distributedBuilds.hostPublicKey = "ssh-ed25519 AAAA..."; # from: ssh-keyscan -t ed25519 "$(hostname)"
+   distributedBuilds.hostPublicKey = "ssh-ed25519 AAAA..."; # from: ssh-keyscan -t ed25519 <hostname>
    ```
-
 2. Generate a store signing key on the builder:
-
+   ```
-   ```sh
    sudo nix key generate-secret --key-name "$(hostname)" | sudo tee /etc/nix/signing-key.sec | sudo nix key convert-secret-to-public
    ```
-
 3. Add the printed public key to `devices.nix`:
-
    ```nix
    distributedBuilds.storeSigningPublicKey = "<hostname>:<base64...>";
    ```
-
 4. Rebuild all machines so they trust the new signing key.

devices.nix

@@ -26,12 +26,6 @@ in
   };
   forgejo-runner-1 = {
     system = "aarch64-linux";
-    distributedBuilds = {
-      isBuilder = true;
-      clientPublicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIK0NLgg0sFobBWz/bjYs9WkrMvlcvJC5F6+3jQ/b+AnD forgejo-runner-1-nix-builds";
-      hostPublicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIANGC89GiT5xCsFICwrharrbV3q7acWHqk6ZwOUXbtGT";
-      storeSigningPublicKey = "forgejo-runner-1:ln1FVLL8G5+IveQuBi/Kn3SaqFZ1gaiQrE3yPlMhCMA=";
-    };
   };
   hetzner-vpn2 = {
     system = "aarch64-linux";

flake.nix

@@ -146,11 +146,7 @@
         niri = niri.overlays.niri;
       };
 
-      nixosModules = (importModuleDir ./nixosModules) // {
+      nixosModules = importModuleDir ./nixosModules;
-        default = {
-          imports = builtins.attrValues (builtins.removeAttrs self.nixosModules [ "default" ]);
-        };
-      };
 
       homeModules = importModuleDir ./homeModules;
       homeConfigurations = {

nixosConfigurations.nix

@@ -3,7 +3,7 @@
   lib,
 }:
 let
-  allDevices = import ./devices.nix { inherit (inputs) self; };
+  devices = import ./devices.nix { inherit (inputs) self; };
   inherit (inputs)
     self
     home-manager
@@ -15,7 +15,7 @@ let
     stylix
     zerforschen-plus
     ;
-  forDevice = f: lib.mapAttrs (device: value: f (value // { inherit device; })) allDevices;
+  forDevice = f: lib.mapAttrs (device: value: f (value // { inherit device; })) devices;
 in
 forDevice (
   {
@@ -24,15 +24,10 @@ forDevice (
     home-manager-users ? { },
     nixosSystem ? inputs.nixpkgs.lib.nixosSystem,
     ...
-  }@thisDevice:
+  }:
   let
     specialArgs = inputs // {
-      inherit
+      inherit device home-manager-users devices;
-        device
-        home-manager-users
-        allDevices
-        thisDevice
-        ;
     };
   in
   nixosSystem {

nixosModules/default.nix

@@ -0,0 +1,39 @@
+{ ... }:
+{
+  imports = [
+    # keep-sorted start
+    ./allowed-unfree-list.nix
+    ./amd-graphics.nix
+    ./autoupdate.nix
+    ./distributed-builds.nix
+    ./en-de.nix
+    ./extra-caches.nix
+    ./firmware-updates.nix
+    ./git.nix
+    ./globalinstalls.nix
+    ./gnome.nix
+    ./intel-graphics.nix
+    ./kdeconnect.nix
+    ./latex.nix
+    ./lix-is-nix.nix
+    ./modern-desktop.nix
+    ./muede-desktop-settings.nix
+    ./nix-ld.nix
+    ./nixpkgs-overlays.nix
+    ./openssh.nix
+    ./podman.nix
+    ./printing.nix
+    ./prometheus-node.nix
+    ./pxvirt-guest.nix
+    ./quiet-boot.nix
+    ./secure-boot.nix
+    ./steam.nix
+    ./stylix.nix
+    ./systemd-boot.nix
+    ./tailscale.nix
+    ./user-muede.nix
+    ./user-ronja.nix
+    ./wine-gaming.nix
+    # keep-sorted end
+  ];
+}

nixosModules/distributed-builds.nix

@@ -1,27 +1,24 @@
 {
   config,
   lib,
-  allDevices,
+  devices,
-  thisDevice,
   ...
 }:
 let
-  clientSshKeyPath = "/etc/nix/distributed-build-key";
+  sshKeyPath = "/etc/nix/distributed-build-key";
   buildUser = "remotebuild";
 
   # Collect all per-device public keys that have been registered.
-  allClientPublicKeys = lib.pipe allDevices [
+  authorizedPublicKeys = lib.pipe devices [
     (lib.filterAttrs (_: v: (v.distributedBuilds or { }) ? clientPublicKey))
     (lib.mapAttrsToList (_: v: v.distributedBuilds.clientPublicKey))
   ];
 
-  isClient = (thisDevice.distributedBuilds or { }) ? clientPublicKey;
-
   buildServerDevices = lib.filterAttrs (
     _: v: (v.distributedBuilds or { }).isBuilder or false
-  ) allDevices;
+  ) devices;
 
-  buildServerKnownHosts = lib.pipe buildServerDevices [
+  knownHosts = lib.pipe buildServerDevices [
     (lib.filterAttrs (_: v: v.distributedBuilds ? hostPublicKey))
     (lib.mapAttrs (
       _: v: {
@@ -30,21 +27,17 @@ let
     ))
   ];
 
-  remoteBuildServerDevices = builtins.filter (
+  buildMachineList = lib.mapAttrsToList (
-    m: m.hostName != config.networking.hostName
+    hostName: v:
-  ) (lib.mapAttrsToList (name: v: v // { hostName = name; }) buildServerDevices);
-
-  buildMachines = map (
-    m:
     {
-      hostName = m.hostName;
+      inherit hostName;
-      systems = [ m.system ];
+      systems = [ v.system ];
       sshUser = buildUser;
-      sshKey = clientSshKeyPath;
+      sshKey = sshKeyPath;
       protocol = "ssh-ng";
     }
-    // lib.optionalAttrs (m.distributedBuilds ? speedFactor) {
+    // lib.optionalAttrs (v.distributedBuilds ? speedFactor) {
-      speedFactor = m.distributedBuilds.speedFactor;
+      speedFactor = v.distributedBuilds.speedFactor;
     }
     // {
       supportedFeatures = [
@@ -54,73 +47,60 @@ let
         "benchmark"
       ];
     }
-  ) remoteBuildServerDevices;
+  ) buildServerDevices;
+
+  remoteMachines = builtins.filter (m: m.hostName != config.networking.hostName) buildMachineList;
 in
 {
   options.my.distributedBuilds.enable = lib.mkEnableOption "distributed Nix builds";
 
-  config = lib.mkIf config.my.distributedBuilds.enable (
+  config = lib.mkIf config.my.distributedBuilds.enable {
-    lib.mkMerge [
+    programs.ssh.knownHosts = knownHosts;
 
-      # All machines
+    # Dedicated user for receiving distributed build connections
-      {
+    users.users.${buildUser} = {
-        nix.settings = {
+      isSystemUser = true;
-          trusted-public-keys = lib.pipe buildServerDevices [
+      group = buildUser;
-            (lib.mapAttrsToList (_: v: v.distributedBuilds.storeSigningPublicKey or null))
+      useDefaultShell = true;
-            (builtins.filter (k: k != null))
+      openssh.authorizedKeys.keys = map (
-          ];
+        k: ''command="nix daemon --stdio",restrict ${k}''
-          max-jobs = (thisDevice.distributedBuilds or { }).maxJobs or "auto";
+      ) authorizedPublicKeys;
-          cores = 0;
+    };
-          min-free = 10 * 1024 * 1024;
+    users.groups.${buildUser} = { };
-          max-free = 200 * 1024 * 1024;
-        };
-        systemd.services.nix-daemon.serviceConfig = {
-          MemoryAccounting = true;
-          MemoryMax = "90%";
-          OOMScoreAdjust = 500;
-        };
-      }
 
-      # Server: accept incoming build connections
+    nix = {
-      (lib.mkIf (thisDevice.distributedBuilds.isBuilder or false) {
+      distributedBuilds = remoteMachines != [ ];
-        users.users.${buildUser} = {
+      buildMachines = remoteMachines;
-          isSystemUser = true;
+      settings = {
-          group = buildUser;
+        trusted-users = [ buildUser ];
-          useDefaultShell = true;
+        builders-use-substitutes = true;
-          openssh.authorizedKeys.keys = map (
+        # Use build machines as binary caches so already-built paths are downloaded
-            k: ''command="nix daemon --stdio",restrict ${k}''
+        # rather than rebuilt. Only machines with a storeSigningPublicKey are used.
-          ) allClientPublicKeys;
+        substituters = lib.pipe buildServerDevices [
-        };
+          (lib.filterAttrs (_: v: v.distributedBuilds ? storeSigningPublicKey))
-        users.groups.${buildUser} = { };
+          (lib.mapAttrsToList (hostName: _: "ssh-ng://${buildUser}@${hostName}"))
-        nix.settings = {
+          (lib.filter (s: s != "ssh-ng://${buildUser}@${config.networking.hostName}"))
-          trusted-users = [ buildUser ];
+        ];
-          secret-key-files = [ "/etc/nix/signing-key.sec" ];
+        trusted-public-keys = lib.pipe buildServerDevices [
-        };
+          (lib.mapAttrsToList (_: v: v.distributedBuilds.storeSigningPublicKey or null))
-      })
+          (builtins.filter (k: k != null))
+        ];
+        secret-key-files =
+          let
+            thisDevice = devices.${config.networking.hostName} or { };
+          in
+          lib.optional (thisDevice.distributedBuilds.isBuilder or false) "/etc/nix/signing-key.sec";
+        max-jobs = (devices.${config.networking.hostName}.distributedBuilds or { }).maxJobs or "auto";
+        cores = 0;
+        min-free = 10 * 1024 * 1024;
+        max-free = 200 * 1024 * 1024;
+      };
+    };
 
-      # Client: connect to build servers for building and substitution
+    systemd.services.nix-daemon.serviceConfig = {
-      (lib.mkIf isClient {
+      MemoryAccounting = true;
-        programs.ssh = {
+      MemoryMax = "90%";
-          knownHosts = buildServerKnownHosts;
+      OOMScoreAdjust = 500;
-          extraConfig = ''
+    };
-            Host ${lib.concatStringsSep " " (lib.attrNames buildServerDevices)}
+  };
-              User ${buildUser}
-              IdentityFile ${clientSshKeyPath}
-              IdentitiesOnly yes
-          '';
-        };
-        nix = {
-          distributedBuilds = buildMachines != [ ];
-          buildMachines = buildMachines;
-          settings = {
-            builders-use-substitutes = true;
-            substituters = map (m: "ssh-ng://${buildUser}@${m.hostName}") (
-              builtins.filter (m: m.distributedBuilds ? storeSigningPublicKey) remoteBuildServerDevices
-            );
-          };
-        };
-      })
-
-    ]
-  );
 }