feat: dump to cousegraph on course publish signal

Previously, CourseGraph needed to be kept up-to-date by
running `./manage.py dump_to_neo4j ...` manually or on a cron timer.

This introduces a CMS new setting: COURSEGRAPH_DUMP_COURSE_ON_PUBLISH.
When enabled, the CMS course_published signal handler will
asynchronously dump each individual course to CourseGraph when it
is published.

This follows a pattern established by other subsystems like
learning_sequences and special exam registration, both of which
fire off asynchronous post-processing tasks from the course-
publish handler.

cms/djangoapps/contentstore/signals/handlers.py

@@ -5,6 +5,7 @@ import logging
 from datetime import datetime
 from functools import wraps
 
+from django.conf import settings
 from django.core.cache import cache
 from django.dispatch import receiver
 from pytz import UTC
@@ -55,6 +56,9 @@ def listen_for_course_publish(sender, course_key, **kwargs):  # pylint: disable=
         update_search_index,
         update_special_exams_and_publish
     )
+    from cms.djangoapps.coursegraph.tasks import (
+        dump_course_to_neo4j
+    )
 
     # register special exams asynchronously
     course_key_str = str(course_key)
@@ -64,6 +68,10 @@ def listen_for_course_publish(sender, course_key, **kwargs):  # pylint: disable=
         # Push the course outline to learning_sequences asynchronously.
         update_outline_from_modulestore_task.delay(course_key_str)
 
+    if settings.COURSEGRAPH_DUMP_COURSE_ON_PUBLISH:
+        # Push the course out to CourseGraph asynchronously.
+        dump_course_to_neo4j.delay(course_key_str)
+
     # Finally, call into the course search subsystem
     # to kick off an indexing action
     if CoursewareSearchIndexer.indexing_is_enabled() and CourseAboutSearchIndexer.indexing_is_enabled():

cms/envs/common.py

@@ -2253,6 +2253,16 @@ COURSEGRAPH_CONNECTION: dict = {
     "password": None,
 }
 
+# .. toggle_name: COURSEGRAPH_DUMP_COURSE_ON_PUBLISH
+# .. toggle_implementation: DjangoSetting
+# .. toggle_creation_date: 2022-01-27
+# .. toggle_use_cases: open_edx
+# .. toggle_default: False
+# .. toggle_description: Whether, upon publish, a course should automatically
+#      be exported to Neo4j via the connection parameters specified in
+#      `COURSEGRAPH_CONNECTION`.
+COURSEGRAPH_DUMP_COURSE_ON_PUBLISH: bool = False
+
 ########## Settings for video transcript migration tasks ############
 VIDEO_TRANSCRIPT_MIGRATIONS_JOB_QUEUE = DEFAULT_PRIORITY_QUEUE