Working backplane dyndns client/server

lib/dns.nix

@@ -0,0 +1,58 @@
+{ lib }:
+
+with lib;
+let
+  join-lines = concatStringsSep "\n";
+
+  makeSrvRecords = protocol: type: records:
+    join-lines (map (record:
+      "_${type}._${protocol} IN SRV ${toString record.priority} ${toString record.weight} ${toString record.port} ${record.host}.")
+    records);
+
+  makeSrvProtocolRecords = protocol: types: join-lines (mapAttrsToList (makeSrvRecords protocol) types);
+
+  srvRecordOpts = with types; {
+    options = {
+      weight = mkOption {
+        type = int;
+        description = "Weight relative to other records.";
+        default = 1;
+      };
+
+      priority = mkOption {
+        type = int;
+        description = "Priority to give this record.";
+        default = 0;
+      };
+
+      port = mkOption {
+        type = port;
+        description = "Port to use when connecting.";
+      };
+
+      host = mkOption {
+        type = str;
+        description = "Host to contact for this service.";
+        example = "my-host.my-domain.com.";
+      };
+    };
+  };
+
+  srvRecordPair = domain: protocol: type: record: {
+    "_${type}._${protocol}.${domain}" = "${toString record.priority} ${toString record.weight} ${toString record.port} ${record.host}.";
+  };
+
+in rec {
+
+  srvRecords = with types; attrsOf (attrsOf (listOf (submodule srvRecordOpts)));
+
+  srvRecordsToBindZone = srvRecords: join-lines (mapAttrsToList makeSrvProtocolRecords srvRecords);
+
+  concatMapAttrs = f: attrs: concatMap (x: x) (mapAttrsToList (key: val: f key val) attrs);
+
+  srvRecordsToPairs = domain: srvRecords:
+    listToAttrs
+      (concatMapAttrs (protocol: types:
+        concatMapAttrs (type: records: map (srvRecordPair domain protocol type) records) types)
+        srvRecords);
+}

lib/utils.nix

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+{ lib }:
+
+with lib;
+{
+  recursiveMergeAttrs = a: b: let
+    commonAttrs = intersectLists (attrNames a) (attrNames b);
+    aAttrs = subtractLists (attrNames a) commonAttrs;
+    bAttrs = subtractLists (attrNames b) commonAttrs;
+    aSide = (filterAttrs (k: v: elem k aAttrs) a);
+    bSide = (filterAttrs (k: v: elem k bAttrs) b);
+    common = (foldr (a: b: a // b) {}
+       (map (k: { ${k} = a.${k} // b.${k}; }) commonAttrs));
+  in aSide // bSide // common;
+}