From 8d2bda17f17a9f13f6b071088a6e3fbea4ad99b4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nicolas=20=E2=80=9CNiols=E2=80=9D=20Jeannerod?=
 <nicolas.jeannerod@moduscreate.com>
Date: Mon, 10 Feb 2025 12:24:10 +0100
Subject: [PATCH] Generalise common networking options

- allow disabling IPv4 or v6 (both enabled by default)
- allow specifying interface (defaults to eth0)
---
 infra/common/nixos/networking.nix | 84 +++++++++++++++----------------
 infra/common/options.nix          | 22 ++++++++
 2 files changed, 62 insertions(+), 44 deletions(-)

diff --git a/infra/common/nixos/networking.nix b/infra/common/nixos/networking.nix
index 7b2b2fee..37100efd 100644
--- a/infra/common/nixos/networking.nix
+++ b/infra/common/nixos/networking.nix
@@ -1,7 +1,7 @@
 { config, lib, ... }:
 
 let
-  inherit (lib) mkDefault;
+  inherit (lib) mkDefault mkIf mkMerge;
 
 in
 {
@@ -11,53 +11,49 @@ in
       settings.PasswordAuthentication = false;
     };
 
-    networking = {
-      hostName = config.fediversityVm.name;
-      domain = config.fediversityVm.domain;
+    networking = mkMerge [
+      {
+        hostName = config.fediversityVm.name;
+        domain = config.fediversityVm.domain;
 
-      ## REVIEW: Do we actually need that, considering that we have static IPs?
-      useDHCP = mkDefault true;
+        ## REVIEW: Do we actually need that, considering that we have static IPs?
+        useDHCP = mkDefault true;
 
-      interfaces = {
-        eth0 = {
-          ipv4 = {
-            addresses = [
-              {
-                inherit (config.fediversityVm.ipv4) address prefixLength;
-              }
-            ];
-          };
-          ipv6 = {
-            addresses = [
-              {
-                inherit (config.fediversityVm.ipv6) address prefixLength;
-              }
-            ];
-          };
+        nameservers = [
+          "95.215.185.6"
+          "95.215.185.7"
+          "2a00:51c0::5fd7:b906"
+          "2a00:51c0::5fd7:b907"
+        ];
+
+        firewall.enable = false;
+        nftables = {
+          enable = true;
+          rulesetFile = ./nftables-ruleset.nft;
         };
-      };
+      }
 
-      defaultGateway = {
-        address = config.fediversityVm.ipv4.gateway;
-        interface = "eth0";
-      };
-      defaultGateway6 = {
-        address = config.fediversityVm.ipv6.gateway;
-        interface = "eth0";
-      };
+      ## IPv4
+      (mkIf config.fediversityVm.ipv4.enable {
+        interfaces.${config.fediversityVm.ipv4.interface}.ipv4.addresses = [
+          { inherit (config.fediversityVm.ipv4) address prefixLength; }
+        ];
+        defaultGateway = {
+          address = config.fediversityVm.ipv4.gateway;
+          interface = config.fediversityVm.ipv4.interface;
+        };
+      })
 
-      nameservers = [
-        "95.215.185.6"
-        "95.215.185.7"
-        "2a00:51c0::5fd7:b906"
-        "2a00:51c0::5fd7:b907"
-      ];
-
-      firewall.enable = false;
-      nftables = {
-        enable = true;
-        rulesetFile = ./nftables-ruleset.nft;
-      };
-    };
+      ## IPv6
+      (mkIf config.fediversityVm.ipv6.enable {
+        interfaces.${config.fediversityVm.ipv6.interface}.ipv6.addresses = [
+          { inherit (config.fediversityVm.ipv6) address prefixLength; }
+        ];
+        defaultGateway6 = {
+          address = config.fediversityVm.ipv6.gateway;
+          interface = config.fediversityVm.ipv6.interface;
+        };
+      })
+    ];
   };
 }
diff --git a/infra/common/options.nix b/infra/common/options.nix
index 230eea5d..1236c01a 100644
--- a/infra/common/options.nix
+++ b/infra/common/options.nix
@@ -89,6 +89,17 @@ in
     };
 
     ipv4 = {
+      enable = mkOption {
+        default = true;
+      };
+
+      interface = mkOption {
+        description = ''
+          The interface that carries the machine's IPv4 network.
+        '';
+        default = "eth0";
+      };
+
       address = mkOption {
         description = ''
           The IP address of the machine, version 4. It will be injected as a
@@ -114,6 +125,17 @@ in
     };
 
     ipv6 = {
+      enable = mkOption {
+        default = true;
+      };
+
+      interface = mkOption {
+        description = ''
+          The interface that carries the machine's IPv6 network.
+        '';
+        default = "eth0";
+      };
+
       address = mkOption {
         description = ''
           The IP address of the machine, version 6. It will be injected as a