nixos/netbird: automated login using Setup Keys file (#444291)

nixos/modules/services/networking/netbird.nix

@@ -20,6 +20,7 @@ let
     mapAttrsToList
     mkAliasOptionModule
     mkDefault
+    mkEnableOption
     mkIf
     mkMerge
     mkOption
@@ -31,6 +32,7 @@ let
     optionalAttrs
     optionalString
     optionals
+    pipe
     toShellVars
     versionAtLeast
     versionOlder
@@ -40,6 +42,7 @@ let
     attrsOf
     bool
     enum
+    listOf
     nullOr
     package
     path
@@ -222,6 +225,26 @@ in
                 '';
               };
 
+              login.enable = mkEnableOption "automated login for NetBird client";
+              login.setupKeyFile = mkOption {
+                type = nullOr str;
+                default = null;
+                example = "/run/secrets/netbird-priv/setup-key";
+                description = ''
+                  A Setup Key file path used for automated login of the machine.
+                '';
+              };
+              login.systemdDependencies = mkOption {
+                type = listOf str;
+                default = [ ];
+                example = lib.literalExpression ''
+                  [ "sops-install-secrets.service" ]
+                '';
+                description = ''
+                  Additional systemd dependencies required to succeed before the Setup Key file becomes available.
+                '';
+              };
+
               openFirewall = mkOption {
                 type = bool;
                 default = true;
@@ -697,6 +720,71 @@ in
         });
       '';
     })
+    # Setup Keys login automation
+    {
+      systemd.services = pipe cfg.clients [
+        (filterAttrs (_: client: client.login.enable))
+        (mapAttrs' (
+          _: client:
+          nameValuePair "${client.service.name}-login" {
+            after = [ "${client.service.name}.service" ] ++ client.login.systemdDependencies;
+            requires = [ "${client.service.name}.service" ] ++ client.login.systemdDependencies;
+            wantedBy = [ "${client.service.name}.service" ];
+
+            serviceConfig = {
+              Type = "oneshot";
+              RemainAfterExit = true;
+
+              User = client.user.name;
+              Group = client.user.group;
+
+              RemoveIPC = true;
+              PrivateTmp = "disconnected"; # "disconnected" puts /tmp on `tmpfs`
+              ProtectSystem = "strict";
+              ProtectHome = "yes";
+
+              LoadCredential = [ "setup-key:${client.login.setupKeyFile}" ];
+            };
+
+            environment.NB_SETUP_KEY_FILE = "%d/setup-key";
+            /*
+              might want to do something similar to the docker entrypoint (watching log messages) instead
+              see https://github.com/netbirdio/netbird/blob/dc30dcacce4c322502975f1f491e6774efd7e1e9/client/netbird-entrypoint.sh
+            */
+            script = ''
+              set -x
+              # uses a file on a `tmpfs`, because variable updates get lost in the loop
+              status_file="/tmp/status.txt"
+
+              refresh_status() {
+                '${lib.getExe client.wrapper}' status &>"$status_file" || :
+              }
+
+              print_short_setup_key() {
+                cut -b1-8 <"$NB_SETUP_KEY_FILE"
+              }
+
+              main() {
+                refresh_status
+                <"$status_file" sed 's/^/STATUS:PRE-CONNECT : /g'
+
+                until refresh_status && <"$status_file" grep --quiet 'Connected\|NeedsLogin' ; do
+                  sleep 1
+                done
+                <"$status_file" sed 's/^/STATUS:POST-CONNECT: /g'
+
+                if <"$status_file" grep --quiet 'NeedsLogin' ; then
+                  echo "Using Setup Key File with key: $(print_short_setup_key)" >&2
+                  '${lib.getExe client.wrapper}' up --setup-key-file="$NB_SETUP_KEY_FILE"
+                fi
+              }
+
+              main "$@"
+            '';
+          }
+        ))
+      ];
+    }
     # migration & temporary fixups section
     {
       systemd.services = toClientAttrs (