add routes to dump configuration

app.rb

@@ -375,6 +375,12 @@ get "/cookies" do
   jsonify response.headers
 end
 
+get "/config", provides: "json" do
+  pretty = params.key? :pretty
+
+  jsonify config.as_json, pretty:
+end
+
 get "/_cat/headers" do
   stream do |out|
     req_headers.each do |k, v|
@@ -399,6 +405,21 @@ get "/_cat/cookies" do
   end
 end
 
+get "/_cat/config" do
+  stream do |out|
+    config.instance_variables.each do |k|
+      k = k.to_s.delete_prefix "@"
+      begin
+        v = config.send(k)
+      rescue NoMethodError
+        next
+      end
+
+      out << "#{k}(#{v.to_s.length})=#{v}\n"
+    end
+  end
+end
+
 route :delete, :get, :patch, :post, :put, "/status/:code" do
   # hello
   code = Integer(params[:code])