class_docstr: Implementation of :class:`MetricExporter` that prints metrics to a file in a given directory.
  
  This class can be used for diagnostic or testing purposes.
class_docstr_tok: ["Implementation","of",":","class",":","`","MetricExporter","`","that","prints","metrics","to","a","file","in","a","given","directory",".","This","class","can","be","used","for","diagnostic","or","testing","purposes","."]
code: def export(
      self,
      metrics_data: MetricsData,
      timeout_millis: float = 10_000,
      **kwargs,
  ) -> MetricExportResult:
      self.f.write(metrics_data.to_json())
      self.f.write("\n")
      self.f.flush()
      return MetricExportResult.SUCCESS
  
file_path: jina/tests/unit/serve/instrumentation/conftest.py
imports: import random
  from pathlib import Path
  from typing import Callable, Dict, Tuple
  import opentelemetry.sdk.metrics.export
  import opentelemetry.sdk.metrics.view
  import pytest
  from opentelemetry.sdk.metrics.export import AggregationTemporality, MetricExporter, MetricExportResult, MetricsData, PeriodicExportingMetricReader
label_desc: Use image node_id 2 for calling the DirMetricExporter obj's underlying member method code with example usage: obj.export(metrics_data, timeout_millis) and returns: MetricExportResult