Add 'spec.nix'

spec.nix

@@ -0,0 +1,34 @@
+{ nixpkgs, declInput }: let pkgs = import nixpkgs {}; in {
+	jobsets = pkgs.runCommand "spec.json" {} ''
+		cat <<EOF
+		${builtins.toXML declInput}
+		EOF
+		cat > $out <<EOF
+		{
+			"enabled": 1,
+			"hidden": false,
+			"type": "legacy",
+			"description": "Build packages maintained by me",
+			"nixexprinput": "src",
+			"nixexprpath": "default.nix",
+			"checkinterval": 3600,
+			"schedulingshares": 100,
+			"enableemail": false,
+			"emailoverride": "",
+			"keepnr": 3,
+			"inputs": {
+				"src": {
+					"type": "git",
+					"value": "git://github.com/shlevy/declarative-hydra-example.git master",
+					"emailresponsible": false
+				},
+				"nixpkgs": {
+					"type": "git",
+					"value": "https://github.com/NixOS/nixpkgs.git master",
+					"emailresponsible": false
+				}
+			}
+		}
+		EOF
+	'';
+}