dns: auto-generate zone entries from host configurations

Replace static zone file with dynamically generated records: - Add homelab.dns module with enable/cnames options - Extract IPs from systemd.network configs (filters VPN interfaces) - Use git commit timestamp as zone serial number - Move external hosts to separate external-hosts.nix Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
2026-02-04 21:43:44 +01:00
parent 4ceee04308
commit cee1b264cd
14 changed files with 296 additions and 103 deletions
--- a/lib/dns-zone.nix
+++ b/lib/dns-zone.nix
@@ -0,0 +1,160 @@
+{ lib }:
+let
+  # Pad string on the right to reach a fixed width
+  rightPad = width: str:
+    let
+      len = builtins.stringLength str;
+      padding = if len >= width then "" else lib.strings.replicate (width - len) " ";
+    in
+    str + padding;
+
+  # Extract IP address from CIDR notation (e.g., "10.69.13.5/24" -> "10.69.13.5")
+  extractIP = address:
+    let
+      parts = lib.splitString "/" address;
+    in
+    builtins.head parts;
+
+  # Check if a network interface name looks like a VPN/tunnel interface
+  isVpnInterface = ifaceName:
+    lib.hasPrefix "wg" ifaceName ||
+    lib.hasPrefix "tun" ifaceName ||
+    lib.hasPrefix "tap" ifaceName ||
+    lib.hasPrefix "vti" ifaceName;
+
+  # Extract DNS information from a single host configuration
+  # Returns null if host should not be included in DNS
+  extractHostDNS = name: hostConfig:
+    let
+      cfg = hostConfig.config;
+      # Handle cases where homelab module might not be imported
+      dnsConfig = (cfg.homelab or { }).dns or { enable = true; cnames = [ ]; };
+      hostname = cfg.networking.hostName;
+      networks = cfg.systemd.network.networks or { };
+
+      # Filter out VPN interfaces and find networks with static addresses
+      # Check matchConfig.Name instead of network unit name (which can have prefixes like "40-")
+      physicalNetworks = lib.filterAttrs
+        (netName: netCfg:
+          let
+            ifaceName = netCfg.matchConfig.Name or "";
+          in
+          !(isVpnInterface ifaceName) && (netCfg.address or [ ]) != [ ])
+        networks;
+
+      # Get addresses from physical networks only
+      networkAddresses = lib.flatten (
+        lib.mapAttrsToList
+          (netName: netCfg: netCfg.address or [ ])
+          physicalNetworks
+      );
+
+      # Get the first address, if any
+      firstAddress = if networkAddresses != [ ] then builtins.head networkAddresses else null;
+
+      # Check if host uses DHCP (no static address)
+      usesDHCP = firstAddress == null ||
+        lib.any
+          (netName: (networks.${netName}.networkConfig.DHCP or "no") != "no")
+          (lib.attrNames networks);
+    in
+    if !(dnsConfig.enable or true) || firstAddress == null then
+      null
+    else
+      {
+        inherit hostname;
+        ip = extractIP firstAddress;
+        cnames = dnsConfig.cnames or [ ];
+      };
+
+  # Generate A record line
+  generateARecord = hostname: ip:
+    "${rightPad 20 hostname}IN      A       ${ip}";
+
+  # Generate CNAME record line
+  generateCNAME = alias: target:
+    "${rightPad 20 alias}IN      CNAME   ${target}";
+
+  # Generate zone file from flake configurations and external hosts
+  generateZone =
+    { self
+    , externalHosts
+    , serial
+    , domain ? "home.2rjus.net"
+    , ttl ? 1800
+    , refresh ? 3600
+    , retry ? 900
+    , expire ? 1209600
+    , minTtl ? 120
+    , nameservers ? [ "ns1" "ns2" "ns3" ]
+    , adminEmail ? "admin.test.2rjus.net"
+    }:
+    let
+      # Extract DNS info from all flake hosts
+      nixosConfigs = self.nixosConfigurations or { };
+      hostDNSList = lib.filter (x: x != null) (
+        lib.mapAttrsToList extractHostDNS nixosConfigs
+      );
+
+      # Sort hosts by IP for consistent output
+      sortedHosts = lib.sort (a: b: a.ip < b.ip) hostDNSList;
+
+      # Generate A records for flake hosts
+      flakeARecords = lib.concatMapStringsSep "\n" (host:
+        generateARecord host.hostname host.ip
+      ) sortedHosts;
+
+      # Generate CNAMEs for flake hosts
+      flakeCNAMEs = lib.concatMapStringsSep "\n" (host:
+        lib.concatMapStringsSep "\n" (cname:
+          generateCNAME cname host.hostname
+        ) host.cnames
+      ) (lib.filter (h: h.cnames != [ ]) sortedHosts);
+
+      # Generate A records for external hosts
+      externalARecords = lib.concatStringsSep "\n" (
+        lib.mapAttrsToList (name: ip:
+          generateARecord name ip
+        ) (externalHosts.aRecords or { })
+      );
+
+      # Generate CNAMEs for external hosts
+      externalCNAMEs = lib.concatStringsSep "\n" (
+        lib.mapAttrsToList (alias: target:
+          generateCNAME alias target
+        ) (externalHosts.cnames or { })
+      );
+
+      # NS records
+      nsRecords = lib.concatMapStringsSep "\n" (ns:
+        "                    IN      NS      ${ns}.${domain}."
+      ) nameservers;
+
+      # SOA record
+      soa = ''
+        $ORIGIN ${domain}.
+        $TTL ${toString ttl}
+        @       IN      SOA     ns1.${domain}.      ${adminEmail}. (
+                                ${toString serial}                    ; serial number
+                                ${toString refresh}                    ; refresh
+                                ${toString retry}                     ; retry
+                                ${toString expire}                 ; expire
+                                ${toString minTtl}                     ; ttl
+                                )'';
+    in
+    lib.concatStringsSep "\n\n" (lib.filter (s: s != "") [
+      soa
+      nsRecords
+      "; Flake-managed hosts (auto-generated)"
+      flakeARecords
+      (if flakeCNAMEs != "" then "; Flake-managed CNAMEs\n${flakeCNAMEs}" else "")
+      "; External hosts (not managed by this flake)"
+      externalARecords
+      (if externalCNAMEs != "" then "; External CNAMEs\n${externalCNAMEs}" else "")
+      ""
+    ]);
+
+in
+{
+  inherit extractIP extractHostDNS generateARecord generateCNAME generateZone;
+}