Merge pull request #78745 from bene1618/dhcpcd

nixos/dhcpcd: Add option for dhcpcd waiting behaviour

nixos/modules/services/networking/dhcpcd.nix

···
       # Use the list of allowed interfaces if specified
       ${optionalString (allowInterfaces != null) "allowinterfaces ${toString allowInterfaces}"}
 
+      # Immediately fork to background if specified, otherwise wait for IP address to be assigned
+      ${{
+        background = "background";
+        any = "waitip";
+        ipv4 = "waitip 4";
+        ipv6 = "waitip 6";
+        both = "waitip 4\nwaitip 6";
+        if-carrier-up = "";
+      }.${cfg.wait}}
+
       ${cfg.extraConfig}
     '';
 
···
       '';
     };
 
+    networking.dhcpcd.wait = mkOption {
+      type = types.enum [ "background" "any" "ipv4" "ipv6" "both" "if-carrier-up" ];
+      default = "any";
+      description = ''
+        This option specifies when the dhcpcd service will fork to background.
+        If set to "background", dhcpcd will fork to background immediately.
+        If set to "ipv4" or "ipv6", dhcpcd will wait for the corresponding IP
+        address to be assigned. If set to "any", dhcpcd will wait for any type
+        (IPv4 or IPv6) to be assigned. If set to "both", dhcpcd will wait for
+        both an IPv4 and an IPv6 address before forking.
+        The option "if-carrier-up" is equivalent to "any" if either ethernet
+        is plugged nor WiFi is powered, and to "background" otherwise.
+      '';
+    };
+
   };
 
 
···
         serviceConfig =
           { Type = "forking";
             PIDFile = "/run/dhcpcd.pid";
-            ExecStart = "@${dhcpcd}/sbin/dhcpcd dhcpcd -w --quiet ${optionalString cfg.persistent "--persistent"} --config ${dhcpcdConf}";
+            ExecStart = "@${dhcpcd}/sbin/dhcpcd dhcpcd --quiet ${optionalString cfg.persistent "--persistent"} --config ${dhcpcdConf}";
             ExecReload = "${dhcpcd}/sbin/dhcpcd --rebind";
             Restart = "always";
           };