add a ConsoleExporter for logging (open-telemetry#2099)

alrex · srikanthccv · lzchen · commit c01f308350e6 · 2021-11-03T17:32:17.000-07:00
Co-authored-by: Srikanth Chekuri &lt;srikanth.chekuri92@gmail.com&gt;
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/logs/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/logs/__init__.py
@@ -15,6 +15,7 @@
 import abc
 import atexit
 import concurrent.futures
+import json
 import logging
 import os
 import threading
@@ -25,8 +26,13 @@
 )
 from opentelemetry.sdk.logs.severity import SeverityNumber, std_to_otlp
 from opentelemetry.sdk.resources import Resource
+from opentelemetry.sdk.util import ns_to_iso_str
 from opentelemetry.sdk.util.instrumentation import InstrumentationInfo
-from opentelemetry.trace import get_current_span
+from opentelemetry.trace import (
+    format_span_id,
+    format_trace_id,
+    get_current_span,
+)
 from opentelemetry.trace.span import TraceFlags
 from opentelemetry.util._providers import _load_provider
 from opentelemetry.util._time import _time_ns
@@ -72,6 +78,25 @@ def __eq__(self, other: object) -> bool:
             return NotImplemented
         return self.__dict__ == other.__dict__
 
+    def to_json(self) -> str:
+        return json.dumps(
+            {
+                "body": self.body,
+                "name": self.name,
+                "severity_number": repr(self.severity_number),
+                "severity_text": self.severity_text,
+                "attributes": self.attributes,
+                "timestamp": ns_to_iso_str(self.timestamp),
+                "trace_id": "0x{}".format(format_trace_id(self.trace_id)),
+                "span_id": "0x{}".format(format_span_id(self.span_id)),
+                "trace_flags": self.trace_flags,
+                "resource": repr(self.resource.attributes)
+                if self.resource
+                else "",
+            },
+            indent=4,
+        )
+
 
 class LogData:
     """Readable LogRecord data plus associated InstrumentationLibrary."""
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/logs/export/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/logs/export/__init__.py
@@ -16,11 +16,13 @@
 import collections
 import enum
 import logging
+import sys
 import threading
-from typing import Deque, List, Optional, Sequence
+from os import linesep
+from typing import IO, Callable, Deque, List, Optional, Sequence
 
 from opentelemetry.context import attach, detach, set_value
-from opentelemetry.sdk.logs import LogData, LogProcessor
+from opentelemetry.sdk.logs import LogData, LogProcessor, LogRecord
 from opentelemetry.util._time import _time_ns
 
 _logger = logging.getLogger(__name__)
@@ -60,6 +62,33 @@ def shutdown(self):
         """
 
 
+class ConsoleExporter(LogExporter):
+    """Implementation of :class:`LogExporter` that prints log records to the
+    console.
+
+    This class can be used for diagnostic purposes. It prints the exported
+    log records to the console STDOUT.
+    """
+
+    def __init__(
+        self,
+        out: IO = sys.stdout,
+        formatter: Callable[[LogRecord], str] = lambda record: record.to_json()
+        + linesep,
+    ):
+        self.out = out
+        self.formatter = formatter
+
+    def export(self, batch: Sequence[LogData]):
+        for data in batch:
+            self.out.write(self.formatter(data.log_record))
+        self.out.flush()
+        return LogExportResult.SUCCESS
+
+    def shutdown(self):
+        pass
+
+
 class SimpleLogProcessor(LogProcessor):
     """This is an implementation of LogProcessor which passes
     received logs in the export-friendly LogData representation to the
diff --git a/opentelemetry-sdk/tests/logs/test_export.py b/opentelemetry-sdk/tests/logs/test_export.py
@@ -14,17 +14,31 @@
 
 # pylint: disable=protected-access
 import logging
+import os
+import time
 import unittest
 from concurrent.futures import ThreadPoolExecutor
-from unittest.mock import Mock
+from unittest.mock import Mock, patch
 
 from opentelemetry.sdk import trace
-from opentelemetry.sdk.logs import LogEmitterProvider, OTLPHandler
-from opentelemetry.sdk.logs.export import BatchLogProcessor, SimpleLogProcessor
+from opentelemetry.sdk.logs import (
+    LogData,
+    LogEmitterProvider,
+    LogRecord,
+    OTLPHandler,
+)
+from opentelemetry.sdk.logs.export import (
+    BatchLogProcessor,
+    ConsoleExporter,
+    SimpleLogProcessor,
+)
 from opentelemetry.sdk.logs.export.in_memory_log_exporter import (
     InMemoryLogExporter,
 )
 from opentelemetry.sdk.logs.severity import SeverityNumber
+from opentelemetry.sdk.resources import Resource as SDKResource
+from opentelemetry.sdk.util.instrumentation import InstrumentationInfo
+from opentelemetry.trace import TraceFlags
 from opentelemetry.trace.span import INVALID_SPAN_CONTEXT
 
 
@@ -254,3 +268,55 @@ def bulk_log_and_flush(num_logs):
 
         finished_logs = exporter.get_finished_logs()
         self.assertEqual(len(finished_logs), 2415)
+
+
+class TestConsoleExporter(unittest.TestCase):
+    def test_export(self):  # pylint: disable=no-self-use
+        """Check that the console exporter prints log records."""
+        log_data = LogData(
+            log_record=LogRecord(
+                timestamp=int(time.time() * 1e9),
+                trace_id=2604504634922341076776623263868986797,
+                span_id=5213367945872657620,
+                trace_flags=TraceFlags(0x01),
+                severity_text="WARN",
+                severity_number=SeverityNumber.WARN,
+                name="name",
+                body="Zhengzhou, We have a heaviest rains in 1000 years",
+                resource=SDKResource({"key": "value"}),
+                attributes={"a": 1, "b": "c"},
+            ),
+            instrumentation_info=InstrumentationInfo(
+                "first_name", "first_version"
+            ),
+        )
+        exporter = ConsoleExporter()
+        # Mocking stdout interferes with debugging and test reporting, mock on
+        # the exporter instance instead.
+
+        with patch.object(exporter, "out") as mock_stdout:
+            exporter.export([log_data])
+        mock_stdout.write.assert_called_once_with(
+            log_data.log_record.to_json() + os.linesep
+        )
+
+        self.assertEqual(mock_stdout.write.call_count, 1)
+        self.assertEqual(mock_stdout.flush.call_count, 1)
+
+    def test_export_custom(self):  # pylint: disable=no-self-use
+        """Check that console exporter uses custom io, formatter."""
+        mock_record_str = Mock(str)
+
+        def formatter(record):  # pylint: disable=unused-argument
+            return mock_record_str
+
+        mock_stdout = Mock()
+        exporter = ConsoleExporter(out=mock_stdout, formatter=formatter)
+        log_data = LogData(
+            log_record=LogRecord(),
+            instrumentation_info=InstrumentationInfo(
+                "first_name", "first_version"
+            ),
+        )
+        exporter.export([log_data])
+        mock_stdout.write.assert_called_once_with(mock_record_str)
