feat(droid): add nix-on-droid support and vega host

modules/droid/core/hm.nix

@@ -0,0 +1,32 @@
+{ inputs, config, ... }:
+{
+  flake.modules.droid.core =
+    {
+      hostName,
+      userName,
+      userEmail,
+      ...
+    }:
+    {
+      home-manager = {
+        backupFileExtension = "bak";
+        useGlobalPkgs = true;
+        useUserPackages = true;
+        extraSpecialArgs = {
+          inherit
+            inputs
+            hostName
+            userName
+            userEmail
+            ;
+        };
+
+        config = {
+          imports = [
+            config.flake.modules.homeManager.shell
+            config.flake.modules.homeManager.${hostName}
+          ];
+        };
+      };
+    };
+}

modules/droid/core/nix.nix

@@ -0,0 +1,7 @@
+{
+  flake.modules.droid.core = {
+    nix.extraOptions = ''
+      experimental-features = nix-command flakes
+    '';
+  };
+}

modules/droid/networking/ssh.nix

@@ -0,0 +1,109 @@
+{
+  flake.modules.droid.networking =
+    {
+      config,
+      lib,
+      pkgs,
+      ...
+    }:
+    let
+      # utility functions
+      concatLines = list: builtins.concatStringsSep "\n" list;
+
+      prefixLines = mapper: list: concatLines (map mapper list);
+
+      # could be put in the config
+      configPath = "ssh/sshd_config";
+
+      keysFolder = "/etc/ssh";
+
+      authorizedKeysFolder = "/etc/ssh/authorized_keys.d";
+
+      supportedKeysTypes = [
+        "rsa"
+        "ed25519"
+      ];
+
+      sshd-start-bin = "sshd-start";
+
+      # real config
+      cfg = config.tnix.networking.openssh;
+
+      pathOfKeyOf = type: "${keysFolder}/ssh_host_${type}_key";
+
+      generateKeyOf = type: ''
+        ${lib.getExe' pkgs.openssh "ssh-keygen"} \
+          -t "${type}" \
+          -f "${pathOfKeyOf type}" \
+          -N ""
+      '';
+
+      generateKeyWhenNeededOf = type: ''
+        if [ ! -f ${pathOfKeyOf type} ]; then
+          mkdir --parents ${keysFolder}
+          ${generateKeyOf type}
+        fi
+      '';
+
+      sshd-start = pkgs.writeScriptBin sshd-start-bin ''
+        #!${pkgs.runtimeShell}
+        ${prefixLines generateKeyWhenNeededOf supportedKeysTypes}
+
+        mkdir --parents "${authorizedKeysFolder}"
+        echo "${lib.concatStringsSep "\n" cfg.authorizedKeys}" > ${authorizedKeysFolder}/${config.user.userName}
+
+        echo "Starting sshd in non-daemonized way on port ${lib.concatMapStrings toString cfg.ports}"
+        ${lib.getExe' pkgs.openssh "sshd"} \
+          -f "/etc/${configPath}" \
+          -D # don't detach into a daemon process
+      '';
+    in
+    {
+      options.tnix.networking.openssh = {
+        enable = lib.mkEnableOption ''
+          Whether to enable the OpenSSH secure shell daemon, which
+          allows secure remote logins.
+        '';
+
+        ports = lib.mkOption {
+          type = lib.types.listOf lib.types.port;
+          default = [ 22 ];
+          description = ''
+            Specifies on which ports the SSH daemon listens.
+          '';
+        };
+
+        authorizedKeys = lib.mkOption {
+          type = lib.types.listOf lib.types.str;
+          default = [ ];
+          description = ''
+            Specify a list of public keys to be added to the authorized_keys file.
+          '';
+        };
+      };
+
+      config = lib.mkIf cfg.enable {
+        environment.etc = {
+          "${configPath}".text = ''
+            ${prefixLines (port: "Port ${toString port}") cfg.ports}
+
+            AuthorizedKeysFile ${authorizedKeysFolder}/%u
+
+            LogLevel VERBOSE
+          '';
+        };
+
+        environment.packages = [
+          sshd-start
+          pkgs.openssh
+        ];
+
+        build.activationAfter.sshd = ''
+          SERVER_PID=$(${lib.getExe' pkgs.procps "ps"} -a | ${lib.getExe' pkgs.toybox "grep"} sshd || true)
+          if [ -z "$SERVER_PID" ]; then
+            $DRY_RUN_CMD ${lib.getExe sshd-start}
+          fi
+        '';
+      };
+    };
+}