Merge pull request #5 from szvasas/escape_dot_notation

Introduce escaping of '.' characters in labels

Author: pepov

lib/fluent/plugin/out_tag_normaliser.rb

@@ -72,20 +72,67 @@ def render_tag(record)
 
       def get_key_accessors
         key_accessors = {}
-        keywords = @format.scan(/\$\{([\w\.\/\-]+)}/)
+        keywords = @format.scan(/\$\{([\w\.\/\-\\]+)}/)
         keywords.each do |key|
           placeholder = "${#{key[0]}}"
-          if @key_prefix != ""
-            path = @key_prefix + "." + key[0]
+          if contains_escaped_period?(key[0])
+            path = create_path_with_bracket_notation(key[0])
           else
-            path = key[0]
+            path = create_path(key[0])
           end
-          path = "$." + path
           key_accessors[placeholder] = record_accessor_create(path)
         end
         return key_accessors
       end
 
+      private
+
+      def contains_escaped_period?(key)
+        key.include?('\.')
+      end
+
+      def create_path(key)
+        if @key_prefix != ""
+          path = @key_prefix + "." + key
+        else
+          path = key
+        end
+        path = "$." + path
+      end
+
+      # Produces the output in bracket notation, e.g. $['kubernetes']['labels']['app.tier']"
+      def create_path_with_bracket_notation(key)
+        path = split_by_unescaped_dots(key)
+                .map { |elem| "['#{elem}']" }
+                .join("")
+        if @key_prefix != ""
+          path = "['#{@key_prefix}']" + path
+        end
+        path = "$" + path
+      end
+
+      # Splits the input string by the . character if it is not escaped by \
+      def split_by_unescaped_dots(text)
+        result = []
+        current_part = ""
+        escaped = false
+
+        text.each_char do |char|
+          if char == "\\" && !escaped
+            escaped = true
+          elsif char == "." && !escaped
+            result << current_part
+            current_part = ""
+          else
+            current_part += char
+            escaped = false
+          end
+        end
+
+        result << current_part
+        result
+      end
+
     end
   end
 end

test/plugin/test_out_tag_normaliser.rb

@@ -21,10 +21,37 @@ class TagNormaliserOutputTest < Test::Unit::TestCase
     d = create_driver(config)
     d.run(default_tag: 'test') do
       d.feed("tag1", event_time, record.dup)
+    end
+    events = d.events
+    puts events
+
+    assert_equal("cluster.default.understood-butterfly-nginx-logging-demo-7dcdcfdcd7-h7p9n.nginx", events[0][0])
+  end
+
+  test "escape_test" do
+    config = %[
+      format cluster.${namespace_name}.${labels.app}.${labels.app\\.tier}.${labels.app\\.kubernetes\\.io/managed-by}
+    ]
+    record = {
+        "log" => "Example",
+        "kubernetes" => {
+            "pod_name" => "understood-butterfly-nginx-logging-demo-7dcdcfdcd7-h7p9n",
+            "namespace_name" => "default",
+            "labels" => {
+              "app" => "nginx",
+              "app.tier" => "frontend",
+              "app.kubernetes.io/managed-by" => "helm"
+            }
+        }
+    }
+    d = create_driver(config)
+    d.run(default_tag: 'test') do
       d.feed("tag1", event_time, record.dup)
     end
     events = d.events
     puts events
+
+    assert_equal("cluster.default.nginx.frontend.helm", events[0][0])
   end
 
   private