Add support for JSON formatted logs

notebook/log.py

@@ -9,6 +9,10 @@
 from tornado.log import access_log
 from .prometheus.log_functions import prometheus_log_method
 
+from .utils import enable_json_logs
+
+_enable_json_logs = enable_json_logs()
+
 
 def log_request(handler):
     """log a bit more information about each request than tornado's default
@@ -46,5 +50,11 @@ def log_request(handler):
     if status >= 500 and status != 502:
         # log all headers if it caused an error
         log_method(json.dumps(dict(request.headers), indent=2))
-    log_method(msg.format(**ns))
+    if _enable_json_logs:
+        # FIXME: this still logs the msg as a serialized json string,
+        # presumably because it's using tornado's access_log rather than
+        # the logger setup in notebook app with _log_formatter_cls.
+        log_method(ns)
+    else:
+        log_method(msg.format(**ns))
     prometheus_log_method(handler)

notebook/notebookapp.py

@@ -113,6 +113,7 @@
 from ._tz import utcnow, utcfromtimestamp
 from .utils import (
     check_pid,
+    enable_json_logs,
     pathname2url,
     run_sync,
     unix_socket_in_use,
@@ -138,6 +139,19 @@
 except ImportError:
     terminado_available = False
 
+# Tolerate missing json_logging package.
+_enable_json_logs = enable_json_logs()
+try:
+    import json_logging
+except ImportError:
+    # If configured for json logs and we can't do it, log a hint.
+    if _enable_json_logs:
+        logging.getLogger(__name__).exception(
+            'Unable to use json logging due to missing packages. '
+            'Run "pip install notebook[json-logging]" to fix.'
+        )
+    _enable_json_logs = False
+
 #-----------------------------------------------------------------------------
 # Module globals
 #-----------------------------------------------------------------------------
@@ -702,7 +716,9 @@ class NotebookApp(JupyterApp):
         password=(NotebookPasswordApp, NotebookPasswordApp.description.splitlines()[0]),
     )
 
-    _log_formatter_cls = LogFormatter
+    # Unless there is a way to re-initialize the log formatter (like with _log_format_changed?)
+    # we need to load the json logging formatter early here otherwise traitlets complains.
+    _log_formatter_cls = json_logging.JSONLogFormatter if _enable_json_logs else LogFormatter
 
     @default('log_level')
     def _default_log_level(self):

notebook/utils.py

@@ -401,3 +401,7 @@ def unix_socket_in_use(socket_path):
         return True
     finally:
         sock.close()
+
+
+def enable_json_logs():
+    return os.getenv('ENABLE_JSON_LOGGING', 'false').lower() == 'true'

setup.py

@@ -120,6 +120,7 @@
                  'nbval', 'nose-exclude', 'selenium', 'pytest', 'pytest-cov'],
         'docs': ['sphinx', 'nbsphinx', 'sphinxcontrib_github_alt', 'sphinx_rtd_theme'],
         'test:sys_platform != "win32"': ['requests-unixsocket'],
+        'json-logging': ['json-logging']
     },
     python_requires = '>=3.5',
     entry_points = {