Revert "contrib/flask: remove deprecated log shipping integration (elastic#2346)"

This reverts commit 39f4191.

Author: xrmx

elasticapm/contrib/flask/__init__.py

@@ -31,15 +31,19 @@
 
 from __future__ import absolute_import
 
+import logging
+import warnings
+
 import flask
 from flask import request, signals
 
 import elasticapm
 import elasticapm.instrumentation.control
 from elasticapm import get_client
 from elasticapm.base import Client
-from elasticapm.conf import constants
+from elasticapm.conf import constants, setup_logging
 from elasticapm.contrib.flask.utils import get_data_from_request, get_data_from_response
+from elasticapm.handlers.logging import LoggingHandler
 from elasticapm.traces import execution_context
 from elasticapm.utils import build_name_with_http_method_prefix
 from elasticapm.utils.disttracing import TraceParent
@@ -77,8 +81,14 @@ class ElasticAPM(object):
     >>> elasticapm.capture_message('hello, world!')
     """
 
-    def __init__(self, app=None, client=None, client_cls=Client, **defaults) -> None:
+    def __init__(self, app=None, client=None, client_cls=Client, logging=False, **defaults) -> None:
         self.app = app
+        self.logging = logging
+        if self.logging:
+            warnings.warn(
+                "Flask log shipping is deprecated. See the Flask docs for more info and alternatives.",
+                DeprecationWarning,
+            )
         self.client = client or get_client()
         self.client_cls = client_cls
 
@@ -117,6 +127,14 @@ def init_app(self, app, **defaults) -> None:
 
             self.client = self.client_cls(config, **defaults)
 
+        # 0 is a valid log level (NOTSET), so we need to check explicitly for it
+        if self.logging or self.logging is logging.NOTSET:
+            if self.logging is not True:
+                kwargs = {"level": self.logging}
+            else:
+                kwargs = {}
+            setup_logging(LoggingHandler(self.client, **kwargs))
+
         signals.got_request_exception.connect(self.handle_exception, sender=app, weak=False)
 
         try:

tests/contrib/flask/flask_tests.py

@@ -441,6 +441,32 @@ def test_rum_tracing_context_processor(flask_apm_client):
         assert callable(context["apm"]["span_id"])
 
 
+@pytest.mark.parametrize("flask_apm_client", [{"logging": True}], indirect=True)
+def test_logging_enabled(flask_apm_client):
+    logger = logging.getLogger()
+    logger.error("test")
+    error = flask_apm_client.client.events[ERROR][0]
+    assert error["log"]["level"] == "error"
+    assert error["log"]["message"] == "test"
+
+
+@pytest.mark.parametrize("flask_apm_client", [{"logging": False}], indirect=True)
+def test_logging_disabled(flask_apm_client):
+    logger = logging.getLogger()
+    logger.error("test")
+    assert len(flask_apm_client.client.events[ERROR]) == 0
+
+
+@pytest.mark.parametrize("flask_apm_client", [{"logging": logging.ERROR}], indirect=True)
+def test_logging_by_level(flask_apm_client):
+    logger = logging.getLogger()
+    logger.warning("test")
+    logger.error("test")
+    assert len(flask_apm_client.client.events[ERROR]) == 1
+    error = flask_apm_client.client.events[ERROR][0]
+    assert error["log"]["level"] == "error"
+
+
 def test_flask_transaction_ignore_urls(flask_apm_client):
     resp = flask_apm_client.app.test_client().get("/users/")
     resp.close()