Add GAE and GKE fluentd Handlers

docs/index.rst

@@ -111,6 +111,8 @@
   logging-sink
   logging-stdlib-usage
   logging-handlers
+  logging-handlers-app-engine
+  logging-handlers-container-engine
   logging-transports-sync
   logging-transports-thread
   logging-transports-base

docs/logging-handlers-app-engine.rst

@@ -0,0 +1,6 @@
+Google App Engine flexible Log Handler
+======================================
+
+.. automodule:: google.cloud.logging.handlers.app_engine
+  :members:
+  :show-inheritance:

docs/logging-handlers-container-engine.rst

@@ -0,0 +1,6 @@
+Google Container Engine Log Handler
+===================================
+
+.. automodule:: google.cloud.logging.handlers.container_engine
+  :members:
+  :show-inheritance:

docs/logging-usage.rst

@@ -267,3 +267,108 @@ Delete a sink:
     :start-after: [START sink_delete]
     :end-before: [END sink_delete]
     :dedent: 4
+
+Integration with Python logging module
+--------------------------------------
+
+It's possible to tie the Python :mod:`logging` module directly into Google
+Stackdriver Logging. There are different handler options to accomplish this.
+To automatically pick the default for your current environment, use
+:meth:`~google.cloud.logging.client.Client.get_default_handler`.
+
+.. literalinclude:: logging_snippets.py
+    :start-after: [START create_default_handler]
+    :end-before: [END create_default_handler]
+    :dedent: 4
+
+It is also possible to attach the handler to the root Python logger, so that
+for example a plain ``logging.warn`` call would be sent to Stackdriver Logging,
+as well as any other loggers created. A helper method
+:meth:`~google.cloud.logging.client.Client.setup_logging` is provided
+to configure this automatically.
+
+.. literalinclude:: logging_snippets.py
+    :start-after: [START setup_logging]
+    :end-before: [END setup_logging]
+    :dedent: 4
+
+.. note::
+
+    To reduce cost and quota usage, do not enable Stackdriver logging
+    handlers while testing locally.
+
+You can also exclude certain loggers:
+
+.. literalinclude:: logging_snippets.py
+    :start-after: [START setup_logging_excludes]
+    :end-before: [END setup_logging_excludes]
+    :dedent: 4
+
+Cloud Logging Handler
+=====================
+
+If you prefer not to use
+:meth:`~google.cloud.logging.client.Client.get_default_handler`, you can
+directly create a
+:class:`~google.cloud.logging.handlers.handlers.CloudLoggingHandler` instance
+which will write directly to the API.
+
+.. literalinclude:: logging_snippets.py
+    :start-after: [START create_cloud_handler]
+    :end-before: [END create_cloud_handler]
+    :dedent: 4
+
+.. note::
+
+    This handler by default uses an asynchronous transport that sends log
+    entries on a background thread. However, the API call will still be made
+    in the same process. For other transport options, see the transports
+    section.
+
+All logs will go to a single custom log, which defaults to "python". The name
+of the Python logger will be included in the structured log entry under the
+"python_logger" field. You can change it by providing a name to the handler:
+
+.. literalinclude:: logging_snippets.py
+    :start-after: [START create_named_handler]
+    :end-before: [END create_named_handler]
+    :dedent: 4
+
+fluentd logging handlers
+========================
+
+Besides :class:`~google.cloud.logging.handlers.handlers.CloudLoggingHandler`,
+which writes directly to the API, two other handlers are provided.
+:class:`~google.cloud.logging.handlers.app_engine.AppEngineHandler`, which is
+recommended when running on the Google App Engine Flexible vanilla runtimes
+(i.e. your app.yaml contains ``runtime: python``), and
+:class:`~google.cloud.logging.handlers.container_engine.ContainerEngineHandler`
+, which is recommended when running on `Google Container Engine`_ with the
+Stackdriver Logging plugin enabled.
+
+:meth:`~google.cloud.logging.client.Client.get_default_handler` and
+:meth:`~google.cloud.logging.client.Client.setup_logging` will attempt to use
+the environment to automatically detect whether the code is running in
+these platforms and use the appropriate handler.
+
+In both cases, the fluentd agent is configured to automatically parse log files
+in an expected format and forward them to Stackdriver logging. The handlers
+provided help set the correct metadata such as log level so that logs can be
+filtered accordingly.
+
+Cloud Logging Handler transports
+=================================
+
+The :class:`~google.cloud.logging.handlers.handlers.CloudLoggingHandler`
+logging handler can use different transports. The default is
+:class:`~google.cloud.logging.handlers.BackgroundThreadTransport`.
+
+ 1. :class:`~google.cloud.logging.handlers.BackgroundThreadTransport` this is
+    the default. It writes entries on a background
+    :class:`python.threading.Thread`.
+
+ 1. :class:`~google.cloud.logging.handlers.SyncTransport` this handler does a
+    direct API call on each logging statement to write the entry.
+
+
+.. _Google Container Engine: https://cloud.google.com/container-engine/

docs/logging_snippets.py

@@ -324,6 +324,44 @@ def sink_pubsub(client, to_delete):
     to_delete.pop(0)
 
 
+@snippet
+def logging_handler(client):
+    # [START create_default_handler]
+    import logging
+    handler = client.get_default_handler()
+    cloud_logger = logging.getLogger('cloudLogger')
+    cloud_logger.setLevel(logging.INFO)
+    cloud_logger.addHandler(handler)
+    cloud_logger.error('bad news')
+    # [END create_default_handler]
+
+    # [START create_cloud_handler]
+    from google.cloud.logging.handlers import CloudLoggingHandler
+    handler = CloudLoggingHandler(client)
+    cloud_logger = logging.getLogger('cloudLogger')
+    cloud_logger.setLevel(logging.INFO)
+    cloud_logger.addHandler(handler)
+    cloud_logger.error('bad news')
+    # [END create_cloud_handler]
+
+    # [START create_named_handler]
+    handler = CloudLoggingHandler(client, name='mycustomlog')
+    # [END create_named_handler]
+
+
+@snippet
+def setup_logging(client):
+    import logging
+    # [START setup_logging]
+    client.setup_logging(log_level=logging.INFO)
+    # [END setup_logging]
+
+    # [START setup_logging_excludes]
+    client.setup_logging(log_level=logging.INFO,
+                         excluded_loggers=('werkzeug',))
+    # [END setup_logging_excludes]
+
+
 def _line_no(func):
     return func.__code__.co_firstlineno
 

logging/google/cloud/logging/client.py

@@ -14,6 +14,7 @@
 
 """Client for interacting with the Google Stackdriver Logging API."""
 
+import logging
 import os
 
 try:
@@ -34,6 +35,12 @@
 from google.cloud.logging._http import _LoggingAPI as JSONLoggingAPI
 from google.cloud.logging._http import _MetricsAPI as JSONMetricsAPI
 from google.cloud.logging._http import _SinksAPI as JSONSinksAPI
+from google.cloud.logging.handlers import CloudLoggingHandler
+from google.cloud.logging.handlers import AppEngineHandler
+from google.cloud.logging.handlers import ContainerEngineHandler
+from google.cloud.logging.handlers import setup_logging
+from google.cloud.logging.handlers.handlers import EXCLUDED_LOGGER_DEFAULTS
+
 from google.cloud.logging.logger import Logger
 from google.cloud.logging.metric import Metric
 from google.cloud.logging.sink import Sink
@@ -42,6 +49,15 @@
 _DISABLE_GAX = os.getenv(DISABLE_GRPC, False)
 _USE_GAX = _HAVE_GAX and not _DISABLE_GAX
 
+_APPENGINE_FLEXIBLE_ENV_VM = 'GAE_APPENGINE_HOSTNAME'
+"""Environment variable set in App Engine when vm:true is set."""
+
+_APPENGINE_FLEXIBLE_ENV_FLEX = 'GAE_INSTANCE'
+"""Environment variable set in App Engine when env:flex is set."""
+
+_CONTAINER_ENGINE_ENV = 'KUBERNETES_SERVICE'
+"""Environment variable set in a Google Container Engine environment."""
+
 
 class Client(JSONClient):
     """Client to bundle configuration needed for API requests.
@@ -264,3 +280,40 @@ def list_metrics(self, page_size=None, page_token=None):
         """
         return self.metrics_api.list_metrics(
             self.project, page_size, page_token)
+
+    def get_default_handler(self):
+        """Return the default logging handler based on the local environment.
+
+        :rtype: :class:`logging.Handler`
+        :returns: The default log handler based on the environment
+        """
+        if (_APPENGINE_FLEXIBLE_ENV_VM in os.environ or
+                _APPENGINE_FLEXIBLE_ENV_FLEX in os.environ):
+            return AppEngineHandler()
+        elif _CONTAINER_ENGINE_ENV in os.environ:
+            return ContainerEngineHandler()
+        else:
+            return CloudLoggingHandler(self)
+
+    def setup_logging(self, log_level=logging.INFO,
+                      excluded_loggers=EXCLUDED_LOGGER_DEFAULTS):
+        """Attach default Stackdriver logging handler to the root logger.
+
+        This method uses the default log handler, obtained by
+        :meth:`~get_default_handler`, and attaches it to the root Python
+        logger, so that a call such as ``logging.warn``, as well as all child
+        loggers, will report to Stackdriver logging.
+
+        :type log_level: int
+        :param log_level: (Optional) Python logging log level. Defaults to
+                          :const:`logging.INFO`.
+
+        :type excluded_loggers: tuple
+        :param excluded_loggers: (Optional) The loggers to not attach the
+                                 handler to. This will always include the
+                                 loggers in the path of the logging client
+                                 itself.
+        """
+        handler = self.get_default_handler()
+        setup_logging(handler, log_level=log_level,
+                      excluded_loggers=excluded_loggers)

logging/google/cloud/logging/handlers/__init__.py

@@ -14,5 +14,8 @@
 
 """Python :mod:`logging` handlers for Google Cloud Logging."""
 
+from google.cloud.logging.handlers.app_engine import AppEngineHandler
+from google.cloud.logging.handlers.container_engine import (
+    ContainerEngineHandler)
 from google.cloud.logging.handlers.handlers import CloudLoggingHandler
 from google.cloud.logging.handlers.handlers import setup_logging

logging/google/cloud/logging/handlers/_helpers.py

@@ -0,0 +1,39 @@
+# Copyright 2016 Google Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helper functions for logging handlers."""
+
+import math
+import json
+
+
+def format_stackdriver_json(record, message):
+    """Helper to format a LogRecord in in Stackdriver fluentd format.
+
+        :rtype: str
+        :returns: JSON str to be written to the log file.
+    """
+    subsecond, second = math.modf(record.created)
+
+    payload = {
+        'message': message,
+        'timestamp': {
+            'seconds': int(second),
+            'nanos': int(subsecond * 1e9),
+        },
+        'thread': record.thread,
+        'severity': record.levelname,
+    }
+
+    return json.dumps(payload)

logging/google/cloud/logging/handlers/app_engine.py

@@ -0,0 +1,73 @@
+# Copyright 2016 Google Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Logging handler for App Engine Flexible
+
+Logs to the well-known file that the fluentd sidecar container on App Engine
+Flexible is configured to read from and send to Stackdriver Logging.
+
+See the fluentd configuration here:
+
+https://github.com/GoogleCloudPlatform/appengine-sidecars-docker/tree/master/fluentd_logger
+"""
+
+# This file is largely copied from:
+#  https://github.com/GoogleCloudPlatform/python-compat-runtime/blob/master
+# /appengine-vmruntime/vmruntime/cloud_logging.py
+
+import logging.handlers
+import os
+
+from google.cloud.logging.handlers._helpers import format_stackdriver_json
+
+_LOG_PATH_TEMPLATE = '/var/log/app_engine/app.{pid}.json'
+_MAX_LOG_BYTES = 128 * 1024 * 1024
+_LOG_FILE_COUNT = 3
+
+
+class AppEngineHandler(logging.handlers.RotatingFileHandler):
+    """A handler that writes to the App Engine fluentd Stackdriver log file.
+
+    Writes to the file that the fluentd agent on App Engine Flexible is
+    configured to discover logs and send them to  Stackdriver Logging.
+    Log entries are wrapped in JSON and with appropriate metadata. The
+    process of converting the user's formatted logs into a JSON payload for
+    Stackdriver Logging consumption is implemented as part of the handler
+    itself, and not as a formatting step, so as not to interfere with
+    user-defined logging formats.
+    """
+
+    def __init__(self):
+        """Construct the handler
+
+        Large log entries will get mangled if multiple workers write to the
+        same file simultaneously, so we'll use the worker's PID to pick a log
+        filename.
+        """
+        self.filename = _LOG_PATH_TEMPLATE.format(pid=os.getpid())
+        super(AppEngineHandler, self).__init__(self.filename,
+                                               maxBytes=_MAX_LOG_BYTES,
+                                               backupCount=_LOG_FILE_COUNT)
+
+    def format(self, record):
+        """Format the specified record into the expected JSON structure.
+
+        :type record: :class:`~logging.LogRecord`
+        :param record: the log record
+
+        :rtype: str
+        :returns: JSON str to be written to the log file
+        """
+        message = super(AppEngineHandler, self).format(record)
+        return format_stackdriver_json(record, message)