Configuration Pull Request
[MongoDB uses the `authSource` parameter to determine which database to use for authentication](https://docs.mongodb.com/manual/reference/connection-string/#urioption.authSource). The current configuration generates the module and content store settings with the name `auth_source`.
Defined [here](https://github.com/edx/configuration/blob/master/playbooks/roles/edxapp/defaults/main.yml#L1072) and [here](https://github.com/edx/configuration/blob/master/playbooks/roles/edxapp/defaults/main.yml#L1087)
[PyMongo expects the value to be `authsource`](https://github.com/mongodb/mongo-python-driver/blob/2.9.1/pymongo/common.py#L417) and throws a ConfigurationError when attempting to access the module or content store:
ConfigurationError: Unknown option auth_source
[View full error Traceback](https://pastebin.com/Y94jSzAb)
Make sure that the following steps are done before merging:
[ ] A DevOps team member has approved the PR if it is code shared across multiple services and you don't own all of the services.
[ ] Are you adding any new default values that need to be overridden when this change goes live? If so:
[ ] Update the appropriate internal repo (be sure to update for all our environments)
[ ] If you are updating a secure value rather than an internal one, file a DEVOPS ticket with details.
[ ] Add an entry to the CHANGELOG.
[ ] If you are making a complicated change, have you performed the proper testing specified on the [Ops Ansible Testing Checklist](https://openedx.atlassian.net/wiki/display/EdxOps/Ops+Ansible+Testing+Checklist)? Adding a new variable does not require the full list (although testing on a sandbox is a great idea to ensure it links with your downstream code changes).
[ ] Think about how this change will affect Open edX operators. Have you updated the wiki page for the next Open edX release?