Get topics for consumer group

lib/kafkaex_lag_exporter/topic_name_parser.ex

@@ -0,0 +1,13 @@
+defmodule KafkaexLagExporter.TopicNameParser do
+  @moduledoc "Parse Kafka internal member assignment payload in order to find which topics belong to the consumer group"
+
+  @invalid_topic_characters ~r/[^[:alnum:]\-\._]/
+
+  def parse_topic_names(member_assignment) do
+    member_assignment
+    |> String.chunk(:printable)
+    |> Enum.drop(1)
+    |> Enum.take_every(2)
+    |> Enum.map(fn topic_name -> Regex.replace(@invalid_topic_characters, topic_name, "") end)
+  end
+end

test/topic_name_parser_test.exs

@@ -0,0 +1,30 @@
+defmodule KafkaexLagExporterTopicNameParserTest do
+  use ExUnit.Case
+  doctest KafkaexLagExporter.TopicNameParser
+
+  test "should parse single topic" do
+    test_member_assignment =
+      <<0, 0, 0, 0, 0, 1, 0, 17, 111, 119, 108, 115, 104, 111, 112, 45, 99, 117, 115, 116, 111,
+        109, 101, 114, 115, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0,
+        4, 0>>
+
+    assert KafkaexLagExporter.TopicNameParser.parse_topic_names(test_member_assignment) == [
+             "owlshop-customers"
+           ]
+  end
+
+  test "should parse multiple topics" do
+    test_member_assignment =
+      <<0, 1, 0, 0, 0, 31, 0, 42, 102, 111, 111, 95, 54, 50, 100, 54, 97, 99, 99, 54, 48, 55, 57,
+        56, 48, 101, 49, 50, 52, 54, 49, 54, 100, 98, 55, 99, 0, 0, 0, 1, 0, 0, 0, 1, 0, 42, 102,
+        111, 111, 95, 54, 51, 54, 52, 102, 57, 51, 49, 101, 54, 100, 50, 97, 51, 102, 48, 56, 99,
+        49, 97, 100, 54, 100, 52, 0, 0, 0, 1, 0, 0, 0, 1, 0, 42, 102, 111, 111, 95, 54, 51, 51,
+        50, 101, 100, 56, 49, 48, 57, 100, 101, 48, 48, 98, 52, 51, 55, 49, 57, 49, 57, 48, 56>>
+
+    assert KafkaexLagExporter.TopicNameParser.parse_topic_names(test_member_assignment) == [
+             "foo_62d6acc607980e124616db7c",
+             "foo_6364f931e6d2a3f08c1ad6d4",
+             "foo_6332ed8109de00b437191908"
+           ]
+  end
+end