Split genserver from service

lib/kafkaex_lag_exporter/consumer_offset.ex

@@ -0,0 +1,41 @@
+defmodule KafkaexLagExporter.ConsumerOffset do
+  @moduledoc "Genserver implementation to set offset metrics for consumer groups"
+
+  use GenServer
+
+  require Logger
+
+  @interval 5_000
+
+  def start_link(default) when is_list(default) do
+    GenServer.start_link(__MODULE__, default, name: __MODULE__)
+  end
+
+  @impl true
+  def init(_) do
+    Logger.info("Starting #{__MODULE__}")
+
+    clients = Application.get_env(:brod, :clients)
+    endpoints = clients[:kafka_client][:endpoints] || [{"redpanda", 29_092}]
+
+    Logger.info("Reveived Kafka endpoints: #{inspect(endpoints)}")
+
+    Process.send_after(self(), :tick, @interval)
+
+    {:ok, %{endpoints: endpoints}}
+  end
+
+  @impl true
+  def handle_info(:tick, state) do
+    [endpoint | _] = state.endpoints
+
+    {consumer_lags, consumer_lag_sum} = KafkaexLagExporter.ConsumerOffsetFetcher.get(endpoint)
+
+    KafkaexLagExporter.Metrics.group_lag_per_partition(endpoint, consumer_lags)
+    KafkaexLagExporter.Metrics.group_sum_lag(endpoint, consumer_lag_sum)
+
+    Process.send_after(self(), :tick, @interval)
+
+    {:noreply, state}
+  end
+end