Merge pull request #13692 from edx/common_cleanup/monitoring

Move monitoring from common to openedx/core

openedx/core/djangoapps/monitoring/exceptions.py

@@ -0,0 +1,17 @@
+"""
+Signal handler for exceptions.
+"""
+from django.core.signals import got_request_exception
+from django.dispatch import receiver
+import logging
+
+
+@receiver(got_request_exception)
+def record_request_exception(sender, **kwargs):  # pylint: disable=unused-argument
+    """
+    Logs the stack trace whenever an exception
+    occurs in processing a request.
+    """
+    logging.exception("Uncaught exception from {sender}".format(
+        sender=sender
+    ))

openedx/core/djangoapps/monitoring/signals.py

@@ -0,0 +1,135 @@
+"""
+Add receivers for django signals, and feed data into the monitoring system.
+
+If a model has a class attribute 'METRIC_TAGS' that is a list of strings,
+those fields will be retrieved from the model instance, and added as tags to
+the recorded metrics.
+"""
+
+
+from django.db.models.signals import post_save, post_delete, m2m_changed, post_init
+from django.dispatch import receiver
+
+import dogstats_wrapper as dog_stats_api
+
+
+def _database_tags(action, sender, kwargs):  # pylint: disable=unused-argument
+    """
+    Return a tags for the sender and database used in django.db.models signals.
+
+    Arguments:
+        action (str): What action is being performed on the db model.
+        sender (Model): What model class is the action being performed on.
+        kwargs (dict): The kwargs passed by the model signal.
+    """
+    tags = _model_tags(kwargs, 'instance')
+    tags.append(u'action:{}'.format(action))
+
+    if 'using' in kwargs:
+        tags.append(u'database:{}'.format(kwargs['using']))
+
+    return tags
+
+
+def _model_tags(kwargs, key):
+    """
+    Return a list of all tags for all attributes in kwargs[key].MODEL_TAGS,
+    plus a tag for the model class.
+    """
+    if key not in kwargs:
+        return []
+
+    instance = kwargs[key]
+    tags = [
+        u'{}.{}:{}'.format(key, attr, getattr(instance, attr))
+        for attr in getattr(instance, 'MODEL_TAGS', [])
+    ]
+    tags.append(u'model_class:{}'.format(instance.__class__.__name__))
+    return tags
+
+
+@receiver(post_init, dispatch_uid='edxapp.monitoring.post_init_metrics')
+def post_init_metrics(sender, **kwargs):
+    """
+    Record the number of times that django models are instantiated.
+
+    Args:
+        sender (Model): The model class sending the signals.
+        using (str): The name of the database being used for this initialization (optional).
+        instance (Model instance): The instance being initialized (optional).
+    """
+    tags = _database_tags('initialized', sender, kwargs)
+
+    dog_stats_api.increment('edxapp.db.model', tags=tags)
+
+
+@receiver(post_save, dispatch_uid='edxapp.monitoring.post_save_metrics')
+def post_save_metrics(sender, **kwargs):
+    """
+    Record the number of times that django models are saved (created or updated).
+
+    Args:
+        sender (Model): The model class sending the signals.
+        using (str): The name of the database being used for this update (optional).
+        instance (Model instance): The instance being updated (optional).
+    """
+    action = 'created' if kwargs.pop('created', False) else 'updated'
+
+    tags = _database_tags(action, sender, kwargs)
+    dog_stats_api.increment('edxapp.db.model', tags=tags)
+
+
+@receiver(post_delete, dispatch_uid='edxapp.monitoring.post_delete_metrics')
+def post_delete_metrics(sender, **kwargs):
+    """
+    Record the number of times that django models are deleted.
+
+    Args:
+        sender (Model): The model class sending the signals.
+        using (str): The name of the database being used for this deletion (optional).
+        instance (Model instance): The instance being deleted (optional).
+    """
+    tags = _database_tags('deleted', sender, kwargs)
+
+    dog_stats_api.increment('edxapp.db.model', tags=tags)
+
+
+@receiver(m2m_changed, dispatch_uid='edxapp.monitoring.m2m_changed_metrics')
+def m2m_changed_metrics(sender, **kwargs):
+    """
+    Record the number of times that Many2Many fields are updated. This is separated
+    from post_save and post_delete, because it's signaled by the database model in
+    the middle of the Many2Many relationship, rather than either of the models
+    that are the relationship participants.
+
+    Args:
+        sender (Model): The model class in the middle of the Many2Many relationship.
+        action (str): The action being taken on this Many2Many relationship.
+        using (str): The name of the database being used for this deletion (optional).
+        instance (Model instance): The instance whose many-to-many relation is being modified.
+        model (Model class): The model of the class being added/removed/cleared from the relation.
+    """
+    if 'action' not in kwargs:
+        return
+
+    action = {
+        'post_add': 'm2m.added',
+        'post_remove': 'm2m.removed',
+        'post_clear': 'm2m.cleared',
+    }.get(kwargs['action'])
+
+    if not action:
+        return
+
+    tags = _database_tags(action, sender, kwargs)
+
+    if 'model' in kwargs:
+        tags.append('target_class:{}'.format(kwargs['model'].__name__))
+
+    pk_set = kwargs.get('pk_set', []) or []
+
+    dog_stats_api.increment(
+        'edxapp.db.model',
+        value=len(pk_set),
+        tags=tags
+    )

openedx/core/djangoapps/monitoring/startup.py

@@ -0,0 +1,6 @@
+"""
+Registers signal handlers at startup.
+"""
+# pylint: disable=unused-import
+import openedx.core.djangoapps.monitoring.signals
+import openedx.core.djangoapps.monitoring.exceptions