use structlog's get_logger if it is available (#591)

* use structlog's get_logger if it is available

If the user has set up structlog, this will add some additional context
to each log line, like level and timestamp. E.g.

    {"event": "Read traceparent header 00-42d5718b9ac8289e439a688afb17cbae-d6f9a1dad4c90dec-01"}

becomes

    {"event": "Read traceparent header 00-42d5718b9ac8289e439a688afb17cbae-d6f9a1dad4c90dec-01",
    "timestamp": "2019-09-17T15:37:00.049627Z", "logger": "elasticapm.traces", "level": "debug"}

This can be overridden by setting an environment variable
`ELASTIC_APM_DISABLE_STRUCTLOG` to "true".

* make use of flag necessary to switch to structlog, and add docs

Author: beniwohli

docs/logging.asciidoc

@@ -64,6 +64,12 @@ log = logger.new()
 log.msg("some_event")
 ----
 
+===== Use structlog for agent-internal logging
+
+The Elastic APM Python agent uses logging to log internal events and issues.
+By default, it will use a `logging` logger.
+If your project uses structlog, you can tell the agent to use a structlog logger
+by setting the environment variable `ELASTIC_APM_USE_STRUCTLOG` to `true`.
 
 [[log-correlation]]
 === Log correlation in Elasticsearch

elasticapm/base.py

@@ -48,6 +48,7 @@
 from elasticapm.traces import Tracer, execution_context
 from elasticapm.utils import cgroup, compat, is_master_process, stacks, varmap
 from elasticapm.utils.encoding import enforce_label_format, keyword_field, shorten, transform
+from elasticapm.utils.logging import get_logger
 from elasticapm.utils.module_import import import_string
 from elasticapm.utils.threading import IntervalTimer
 
@@ -83,13 +84,13 @@ class Client(object):
     >>>     print ("Exception caught; reference is %%s" %% ident)
     """
 
-    logger = logging.getLogger("elasticapm")
+    logger = get_logger("elasticapm")
 
     def __init__(self, config=None, **inline):
         # configure loggers first
         cls = self.__class__
-        self.logger = logging.getLogger("%s.%s" % (cls.__module__, cls.__name__))
-        self.error_logger = logging.getLogger("elasticapm.errors")
+        self.logger = get_logger("%s.%s" % (cls.__module__, cls.__name__))
+        self.error_logger = get_logger("elasticapm.errors")
 
         self.tracer = None
         self.processors = []

elasticapm/conf/__init__.py

@@ -36,10 +36,11 @@
 import threading
 
 from elasticapm.utils import compat, starmatch_to_regex
+from elasticapm.utils.logging import get_logger
 
 __all__ = ("setup_logging", "Config")
 
-logger = logging.getLogger("elasticapm.conf")
+logger = get_logger("elasticapm.conf")
 
 
 class ConfigurationError(ValueError):

elasticapm/contrib/async_worker.py

@@ -29,15 +29,15 @@
 #  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 
 
-import logging
 import os
 import sys
 import time
 from threading import Lock, Thread
 
 from elasticapm.utils.compat import queue
+from elasticapm.utils.logging import get_logger
 
-logger = logging.getLogger("elasticapm")
+logger = get_logger("elasticapm")
 
 ELASTIC_APM_WAIT_SECONDS = 10
 

elasticapm/contrib/django/apps.py

@@ -28,7 +28,6 @@
 #  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 #  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-import logging
 from functools import partial
 
 from django.apps import AppConfig
@@ -37,8 +36,9 @@
 from elasticapm.conf import constants
 from elasticapm.contrib.django.client import get_client
 from elasticapm.utils.disttracing import TraceParent
+from elasticapm.utils.logging import get_logger
 
-logger = logging.getLogger("elasticapm.traces")
+logger = get_logger("elasticapm.traces")
 
 ERROR_DISPATCH_UID = "elasticapm-exceptions"
 REQUEST_START_DISPATCH_UID = "elasticapm-request-start"

elasticapm/contrib/django/client.py

@@ -31,8 +31,6 @@
 
 from __future__ import absolute_import
 
-import logging
-
 import django
 from django.conf import settings as django_settings
 from django.core.exceptions import DisallowedHost
@@ -43,6 +41,7 @@
 from elasticapm.conf import constants
 from elasticapm.contrib.django.utils import iterate_with_template_sources
 from elasticapm.utils import compat, encoding, get_url_dict
+from elasticapm.utils.logging import get_logger
 from elasticapm.utils.module_import import import_string
 from elasticapm.utils.wsgi import get_environ, get_headers
 
@@ -78,7 +77,7 @@ def get_client(client=None):
 
 
 class DjangoClient(Client):
-    logger = logging.getLogger("elasticapm.errors.client.django")
+    logger = get_logger("elasticapm.errors.client.django")
 
     def __init__(self, config=None, **inline):
         if config is None:

elasticapm/contrib/django/handlers.py

@@ -39,8 +39,9 @@
 from django.conf import settings as django_settings
 
 from elasticapm.handlers.logging import LoggingHandler as BaseLoggingHandler
+from elasticapm.utils.logging import get_logger
 
-logger = logging.getLogger("elasticapm.logging")
+logger = get_logger("elasticapm.logging")
 
 
 class LoggingHandler(BaseLoggingHandler):

elasticapm/contrib/flask/__init__.py

@@ -31,8 +31,6 @@
 
 from __future__ import absolute_import
 
-import logging
-
 import flask
 from flask import request, signals
 
@@ -45,8 +43,9 @@
 from elasticapm.traces import execution_context
 from elasticapm.utils import build_name_with_http_method_prefix
 from elasticapm.utils.disttracing import TraceParent
+from elasticapm.utils.logging import get_logger
 
-logger = logging.getLogger("elasticapm.errors.client")
+logger = get_logger("elasticapm.errors.client")
 
 
 def make_client(client_cls, app, **defaults):
@@ -128,7 +127,7 @@ def init_app(self, app, **defaults):
             self.client = make_client(self.client_cls, app, **defaults)
 
         # 0 is a valid log level (NOTSET), so we need to check explicitly for it
-        if self.logging or self.logging is 0:
+        if self.logging or self.logging is 0:  # noqa F632
             if self.logging is not True:
                 kwargs = {"level": self.logging}
             else:

elasticapm/contrib/opentracing/span.py

@@ -28,13 +28,12 @@
 #  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 #  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-import logging
-
 from opentracing.span import Span as OTSpanBase
 from opentracing.span import SpanContext as OTSpanContextBase
 
 from elasticapm import traces
 from elasticapm.utils import compat, get_url_dict
+from elasticapm.utils.logging import get_logger
 
 try:
     # opentracing-python 2.1+
@@ -47,7 +46,7 @@
     ot_logs = None
 
 
-logger = logging.getLogger("elasticapm.contrib.opentracing")
+logger = get_logger("elasticapm.contrib.opentracing")
 
 
 class OTSpan(OTSpanBase):

elasticapm/events.py

@@ -29,18 +29,18 @@
 #  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 
 
-import logging
 import random
 import sys
 
 from elasticapm.conf.constants import EXCEPTION_CHAIN_MAX_DEPTH
 from elasticapm.utils import compat, varmap
 from elasticapm.utils.encoding import keyword_field, shorten, to_unicode
+from elasticapm.utils.logging import get_logger
 from elasticapm.utils.stacks import get_culprit, get_stack_info, iter_traceback_frames
 
 __all__ = ("BaseEvent", "Exception", "Message")
 
-logger = logging.getLogger("elasticapm.events")
+logger = get_logger("elasticapm.events")
 
 
 class BaseEvent(object):