[FLINK-13104][metrics][datadog] Log all failed requests

flink-metrics/flink-metrics-datadog/src/main/java/org/apache/flink/metrics/datadog/DatadogHttpClient.java

@@ -119,7 +119,11 @@ public void close() {
  client.connectionPool().evictAll();
  }
 
- private static class EmptyCallback implements Callback {
+ /**
+ * A handler for OkHttpClient callback. In case of error or failure it logs the error at warning level.
+ */
+ protected static class EmptyCallback implements Callback {
+
  private static final EmptyCallback singleton = new EmptyCallback();
 
  public static Callback getEmptyCallback() {
@@ -128,11 +132,15 @@ public static Callback getEmptyCallback() {
 
  @Override
  public void onFailure(Call call, IOException e) {
- LOGGER.debug("Failed sending request to Datadog" , e);
+ LOGGER.warn("Failed sending request to Datadog", e);
  }
 
  @Override
  public void onResponse(Call call, Response response) throws IOException {
+ if (!response.isSuccessful()) {
+ LOGGER.warn("Failed to send request to Datadog (response was {})", response);
+ }
+
  response.close();
  }
  }