Proscribe poor logging practices

.flake8

@@ -2,6 +2,7 @@
 max-line-length = 120
 application-import-names = dmoj,judge,django_ace,event_socket_server
 import-order-style = pycharm
+enable-extensions = G
 ignore =
     W504, # line break occurred after a binary operator
     # allow only generator_stop and annotations future imports

.travis.yml

@@ -1,6 +1,6 @@
 language: python
 python: 3.7
-install: pip install flake8 flake8-import-order flake8-future-import flake8-commas
+install: pip install flake8 flake8-import-order flake8-future-import flake8-commas flake8-logging-format
 script:
   - flake8 --version
   - flake8

dmoj/celery.py

@@ -27,6 +27,5 @@
 
 @task_failure.connect()
 def celery_failure_log(sender, task_id, exception, traceback, *args, **kwargs):
-    logger.exception('Celery Task {task_name}: {task_id} on {hostname}'.format(
-        task_name=sender.name, task_id=task_id, hostname=socket.gethostname(),
-    ), exc_info=(type(exception), exception, traceback))
+    logger.error('Celery Task %s: %s on %s', sender.name, task_id, socket.gethostname(),  # noqa: G201
+                 exc_info=(type(exception), exception, traceback))

judge/utils/pwned.py

@@ -66,9 +66,9 @@ def _get_pwned(prefix):
             ),
         )
         response.raise_for_status()
-    except requests.RequestException as e:
+    except requests.RequestException:
         # Gracefully handle timeouts and HTTP error response codes.
-        log.warning('Skipped Pwned Passwords check due to error: %r', e)
+        log.warning('Skipped Pwned Passwords check due to error', exc_info=True)
         return None
 
     results = {}

judge/utils/texoid.py

@@ -35,10 +35,10 @@ def query_texoid(self, document, hash):
             if e.response.status == 400:
                 logger.error('Texoid failed to render: %s\n%s', document, e.response.text)
             else:
-                logger.exception('Failed to connect to texoid for: %s' % document)
+                logger.exception('Failed to connect to texoid for: %s', document)
             return
         except Exception:
-            logger.exception('Failed to connect to texoid for: %s' % document)
+            logger.exception('Failed to connect to texoid for: %s', document)
             return
 
         try: