Make it easier to override mongodb connection parameters

Pymongo clients can connect to Mongodb with many parameters
(https://pymongo.readthedocs.io/en/stable/api/pymongo/mongo_client.html#pymongo.mongo_client.MongoClient)
but we don't want to create a new Tutor setting for every one of them.
This makes it easy for users to override Mongodb connection parameters,
simply by modifying the `mongodb_parameters` object.
In particular, this makes it easy to add "replicaSet" connection
parameters.
See https://github.com/overhangio/tutor/pull/372

CHANGELOG.md

@@ -4,6 +4,7 @@ Note: Breaking changes between versions are indicated by "💥".
 
 ## Unreleased
 
+- [Improvement] Make it easier to override Mongodb connection parameters
 - [Bugfix] Add support for .woff and .woff2 font files in themes (thanks @mrtndwrd!)
 
 ## v10.3.0 (2020-10-13)

tutor/templates/apps/openedx/config/partials/auth.json

@@ -1,35 +1,13 @@
   "SECRET_KEY": "{{ OPENEDX_SECRET_KEY }}",
   "AWS_ACCESS_KEY_ID": "{{ OPENEDX_AWS_ACCESS_KEY }}",
   "AWS_SECRET_ACCESS_KEY": "{{ OPENEDX_AWS_SECRET_ACCESS_KEY }}",
+  "CONTENTSTORE": null,
+  "DOC_STORE_CONFIG": null,
   {{ patch("openedx-auth", separator=",\n", suffix=",")|indent(2) }}
   "XQUEUE_INTERFACE": {
     "django_auth": null,
     "url": null
   },
-  "CONTENTSTORE": {
-    "ENGINE": "xmodule.contentstore.mongo.MongoContentStore",
-    "DOC_STORE_CONFIG": {
-      "host": "{{ MONGODB_HOST }}",
-      "port": {{ MONGODB_PORT }},
-      {% if MONGODB_USERNAME and MONGODB_PASSWORD %}
-      "user": "{{ MONGODB_USERNAME }}",
-      "password": "{{ MONGODB_PASSWORD }}",
-      {% endif %}
-      "db": "{{ MONGODB_DATABASE }}"
-    }
-  },
-  "DOC_STORE_CONFIG": {
-    "host": "{{ MONGODB_HOST }}",
-    "port": {{ MONGODB_PORT }},
-    {% if MONGODB_USERNAME and MONGODB_PASSWORD %}
-    "user": "{{ MONGODB_USERNAME }}",
-    "password": "{{ MONGODB_PASSWORD }}",
-    {% else %}
-    "user": null,
-    "password": null,
-    {% endif %}
-    "db": "{{ MONGODB_DATABASE }}"
-  },
   "DATABASES": {
     "default": {
       "ENGINE": "django.db.backends.mysql",

tutor/templates/apps/openedx/settings/partials/common_all.py

@@ -2,6 +2,32 @@
 import json
 import os
 
+# Mongodb connection parameters: simply modify `mongodb_parameters` to affect all connections to MongoDb.
+mongodb_parameters = {
+    "host": "{{ MONGODB_HOST }}",
+    "port": {{ MONGODB_PORT }},
+    {% if MONGODB_USERNAME and MONGODB_PASSWORD %}
+    "user": "{{ MONGODB_USERNAME }}",
+    "password": "{{ MONGODB_PASSWORD }}",
+    {% else %}
+    "user": None,
+    "password": None,
+    {% endif %}
+    "db": "{{ MONGODB_DATABASE }}",
+}
+DOC_STORE_CONFIG = mongodb_parameters
+CONTENTSTORE = {
+    "ENGINE": "xmodule.contentstore.mongo.MongoContentStore",
+    "ADDITIONAL_OPTIONS": {},
+    "DOC_STORE_CONFIG": DOC_STORE_CONFIG
+}
+# Load module store settings from config files
+update_module_store_settings(MODULESTORE, doc_store_settings=DOC_STORE_CONFIG)
+DATA_DIR = "/openedx/data/"
+for store in MODULESTORE["default"]["OPTIONS"]["stores"]:
+   store["OPTIONS"]["fs_root"] = DATA_DIR
+
+
 DEFAULT_FROM_EMAIL = ENV_TOKENS.get("DEFAULT_FROM_EMAIL", ENV_TOKENS["CONTACT_EMAIL"])
 DEFAULT_FEEDBACK_EMAIL = ENV_TOKENS.get("DEFAULT_FEEDBACK_EMAIL", ENV_TOKENS["CONTACT_EMAIL"])
 SERVER_EMAIL = ENV_TOKENS.get("SERVER_EMAIL", ENV_TOKENS["CONTACT_EMAIL"])
@@ -15,12 +41,6 @@ BULK_EMAIL_DEFAULT_FROM_EMAIL = ENV_TOKENS.get("BULK_EMAIL_DEFAULT_FROM_EMAIL",
 API_ACCESS_MANAGER_EMAIL = ENV_TOKENS.get("API_ACCESS_MANAGER_EMAIL", ENV_TOKENS["CONTACT_EMAIL"])
 API_ACCESS_FROM_EMAIL = ENV_TOKENS.get("API_ACCESS_FROM_EMAIL", ENV_TOKENS["CONTACT_EMAIL"])
 
-# Load module store settings from config files
-update_module_store_settings(MODULESTORE, doc_store_settings=DOC_STORE_CONFIG)
-DATA_DIR = "/openedx/data/"
-for store in MODULESTORE["default"]["OPTIONS"]["stores"]:
-   store["OPTIONS"]["fs_root"] = DATA_DIR
-
 # Get rid completely of coursewarehistoryextended, as we do not use the CSMH database
 INSTALLED_APPS.remove("coursewarehistoryextended")
 DATABASE_ROUTERS.remove(