nixos/networking: Rebuild resolvconf during activation

This is needed when /etc/resolv.conf is being overriden by networkd
and other configurations. If the file is destroyed by an environment
activation then it must be rebuilt so that applications which interface
with /etc/resolv.conf directly don't break.

1 files changed, 18 insertions, 0 deletions

diff --git a/nixos/modules/config/networking.nix b/nixos/modules/config/networking.nix
index 3ab75123110b..711cbb2b70bb 100644
--- a/nixos/modules/config/networking.nix
+++ b/nixos/modules/config/networking.nix
@@ -98,6 +98,24 @@ in
     # pulled in by this target.
     systemd.targets.ip-up.description = "Services Requiring IP Connectivity";
 
+    # This is needed when /etc/resolv.conf is being overriden by networkd
+    # and other configurations. If the file is destroyed by an environment
+    # activation then it must be rebuilt so that applications which interface
+    # with /etc/resolv.conf directly don't break.
+    system.activationScripts.resolvconf = stringAfter [ "etc" "tmpfs" "var" ]
+      ''
+        # Systemd resolved controls its own resolv.conf
+        rm -f /run/resolvconf/interfaces/systemd
+        ${optionalString config.services.resolved.enable ''
+          rm -rf /run/resolvconf/interfaces
+          mkdir -p /run/resolvconf/interfaces
+          ln -s /run/systemd/resolve/resolv.conf /run/resolvconf/interfaces/systemd
+        ''}
+
+        # Make sure resolv.conf is up to date
+        ${pkgs.openresolv}/bin/resolvconf -u
+      '';
+
   };
 
 }