nixos/security: add acme through dns challenge

few side refactors of this:
- no more `dns.domain`, it all must rely on `fqdn`, prevents
  inconsistencies.
- also added an specific host `tuxcord-acmetest` that uses the key zone
  for `nix.tuxcord.net` to test certificate pulling.

agenix/secrets.nix

@@ -12,4 +12,6 @@ in
 
   "dns/tuxcord.test/tuxcord.test.key.age".publicKeys = [ tuxcord-ca ] ++ builtins.attrValues users;
   "dns/tuxcord.test/sub.tuxcord.test.key.age".publicKeys = [ tuxcord-ca ] ++ builtins.attrValues users;
+
+  "dns/nix.tuxcord.net/nix.tuxcord.net.key.age".publicKeys = [ tuxcord-ca ] ++ builtins.attrValues users;
 }

nixos/common.nix

@@ -28,6 +28,8 @@ in
     ./vm.nix
   ];
 
+  age.secrets.ntfy.file = "${self}/agenix/ntfy.age";
+
   nix = {
     package = inputs'.nix-super.packages.default;
 

nixos/default.nix

@@ -33,5 +33,6 @@ in
     tuxcord-ca = mkSystem "tuxcord-ca" "x86_64-linux";
 
     tuxcord-test = mkSystem "tuxcord-test" "x86_64-linux";
+    tuxcord-acmetest = mkSystem "tuxcord-acmetest" "x86_64-linux";
   };
 }

nixos/hosts/tuxcord-acmetest/default.nix

@@ -0,0 +1,12 @@
+{ config, ... }:
+let
+  inherit (config.networking) fqdn;
+in
+{
+  acme.enable = true;
+  acme.rfc2136.nameserver = "tuxcord.net";
+
+  dns.enable = true;
+  networking.fqdn = "nix.tuxcord.net";
+  time.timeZone = "Europe/Madrid";
+}

nixos/hosts/tuxcord-ca/default.nix

@@ -1,9 +1,13 @@
+{ config, ... }:
 {
   imports = [
     ./hardware.nix
     ./storage.nix
   ];
 
+  acme.enable = true;
+  acme.useSelfDns = true;
+
   dns.enable = true;
   networking.fqdn = "tuxcord.net";
   time.timeZone = "Canada/Eastern";

nixos/hosts/tuxcord-test/default.nix

@@ -1,4 +1,5 @@
 {
+  acme.enable = false;
   dns.enable = true;
   networking.fqdn = "tuxcord.test";
 }

nixos/modules/acme.nix

@@ -0,0 +1,87 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+let
+  inherit (lib)
+    mkIf
+    mkEnableOption
+    mkOption
+    types
+    ;
+
+  inherit (config.networking) fqdn;
+
+  cfg = config.acme;
+in
+{
+  # we'll only support rfc2136 based challenges
+  options.acme = {
+    enable = mkEnableOption "" // {
+      default = true;
+    };
+
+    useSelfDns = mkOption {
+      default = false;
+      description = "Sets values of the self DNS if enabled, otherwise requires manual `rfc2136` nameserver and key values.";
+    };
+
+    rfc2136 = {
+      key = mkOption {
+        type = types.path;
+        default = config.age.secrets."dns/${fqdn}.key.age".path;
+      };
+
+      nameserver = mkOption {
+        type = types.str;
+        default = if cfg.useSelfDns then fqdn else null;
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = with cfg.rfc2136; nameserver != null && key != null;
+        message = "ACME needs rfc2136 parameters to work, consider using `useSelfDns` option.";
+      }
+    ];
+
+    environment.persistence."/persist".directories = [
+      {
+        directory = "/var/lib/acme";
+        group = "acme";
+        user = "acme";
+      }
+    ];
+
+    security.acme = {
+      acceptTerms = true;
+
+      defaults = {
+        email = "error@tuxcord.net";
+        reloadServices = [ "nginx" ];
+        postRun = ''
+          source ${config.age.secrets.ntfy.path}
+          ${pkgs.ntfy-sh}/bin/ntfy publish -T recycle -t "${config.host.name}" "HTTPS certificate has been renewed"
+        '';
+      };
+
+      certs."${fqdn}" = {
+        dnsProvider = "rfc2136";
+        environmentFile = with cfg.rfc2136; builtins.toFile "dns-01-challenge.cfg" ''
+          RFC2136_NAMESERVER=${nameserver}
+          RFC2136_TSIG_FILE="${key}"
+        '';
+        extraDomainNames = [
+          "*.${fqdn}"
+          "${fqdn}"
+        ];
+
+        group = config.services.nginx.group;
+      };
+    };
+  };
+}

nixos/modules/default.nix

@@ -1,5 +1,6 @@
 {
   imports = [
+    ./acme.nix
     ./dns.nix
     ./fail2ban.nix
     ./gitea.nix

nixos/modules/dns.nix

@@ -1,6 +1,8 @@
 { config, lib, ... }:
 let
-  agenixDnsDir = ../../agenix/dns + "/${config.dns.domain}";
+  inherit (config.networking) fqdn;
+
+  agenixDnsDir = ../../agenix/dns + "/${fqdn}";
   agenixKeys = builtins.attrNames (builtins.readDir agenixDnsDir);
 
   keys = map (
@@ -18,7 +20,7 @@ let
     {
       name = zoneDomain;
       path = config.age.secrets."dns/${filename}".path;
-      type = if zoneDomain == config.dns.domain then zonesub else subdomain;
+      type = if zoneDomain == fqdn then zonesub else subdomain;
     }
   ) agenixKeys;
 
@@ -34,11 +36,6 @@ in
     enable = mkEnableOption "" // {
       default = true;
     };
-
-    domain = mkOption {
-      type = with lib.types; str;
-      default = config.networking.fqdn;
-    };
   };
 
   config = mkIf cfg.enable {
@@ -53,7 +50,8 @@ in
           value = {
             file = path;
             group = "named";
-            owner = "named";
+            owner = if config.acme.enable then "acme" else "named";
+            mode = "440";
           };
         }
       ) agenixKeys
@@ -65,7 +63,7 @@ in
       extraConfig = builtins.concatStringsSep "\n" (map (key: "include \"${key.path}\";") keys);
 
       zones = {
-        "${config.dns.domain}" = {
+        "${fqdn}" = {
           # grant "tuxcord.net" zonesub ANY;
           extraConfig = ''
             update-policy {
@@ -74,7 +72,7 @@ in
               )}
             };
           '';
-          file = "/var/dns/${config.dns.domain}.zone"; # need to put default stuff
+          file = "/var/dns/${fqdn}.zone"; # need to put default stuff
           master = true;
         };
       };

nixos/modules/gitea.nix

@@ -1,4 +1,9 @@
 { config, lib, ... }:
+let
+  inherit (config.networking) fqdn;
+
+  isHTTPS = config.acme.enable;
+in
 {
   services.gitea = {
     enable = true;
@@ -8,8 +13,8 @@
 
     lfs.enable = true;
 
-    settings.server.DOMAIN = config.networking.fqdn;
-    # settings.server.ROOT_URL = "https://git.tuxcord.net/"; ? would also depend on ssl status
+    settings.server.DOMAIN = fqdn;
+    settings.server.ROOT_URL = "${if isHTTPS then "https" else "http"}://${fqdn}/";
     settings.server.HTTP_PORT = 3000;
 
     settings.service.DISABLE_REGISTRATION = true;

nixos/modules/nginx.nix

@@ -4,8 +4,12 @@ let
 
   mkVhost =
     attrs:
+    let
+      isAcme = config.acme.enable;
+    in
     {
-      forceSSL = false; # TODO: tweak per host
+      forceSSL = isAcme;
+      useACMEHost = if isAcme then fqdn else null;
     }
     // attrs;