Dynamic openedx settings configuration

`tutor.production` should not be hardcoded in the init scripts. Instead,
we load the `$SERVICE_VARIANT.envs.$SETTINGS` settings.

This was inspired by a conversation on slack:
https://openedx.slack.com/archives/CGE253B7V/p1573561290003700?thread_ts=1573478499.002800&cid=CGE253B7V

Thanks @cacciaresi!

tutor/scripts.py

@@ -59,18 +59,28 @@ def initialise(runner):
 
 
 def create_user_command(superuser, staff, username, email, password=None):
+    command = """
+export DJANGO_SETTINGS_MODULE=$SERVICE_VARIANT.envs.$SETTINGS
+echo "Loading settings $DJANGO_SETTINGS_MODULE"
+"""
+
     opts = ""
     if superuser:
         opts += " --superuser"
     if staff:
         opts += " --staff"
-    command = "./manage.py lms --settings=tutor.production manage_user {opts} {username} {email}\n"
+    command += """
+./manage.py lms manage_user {opts} {username} {email}
+"""
     if password:
-        command += "./manage.py lms --settings=tutor.production shell -c \"from django.contrib.auth import get_user_model; u = get_user_model().objects.get(username='{username}'); u.set_password('{password}'); u.save()\""
+        command += """
+./manage.py lms shell -c "from django.contrib.auth import get_user_model; u = get_user_model().objects.get(username='{username}'); u.set_password('{password}'); u.save()"
+"""
     else:
-        command += (
-            "./manage.py lms --settings=tutor.production changepassword {username}"
-        )
+        command += """
+./manage.py lms changepassword {username}
+"""
+
     return command.format(opts=opts, username=username, email=email, password=password)
 
 

tutor/templates/hooks/cms/importdemocourse

@@ -1,2 +1,5 @@
+export DJANGO_SETTINGS_MODULE=$SERVICE_VARIANT.envs.$SETTINGS
+echo "Loading settings $DJANGO_SETTINGS_MODULE"
+
 git clone https://github.com/edx/edx-demo-course --branch open-release/ironwood.2 --depth 1 ../edx-demo-course
-python ./manage.py cms --settings=tutor.production import ../data ../edx-demo-course
+python ./manage.py cms import ../data ../edx-demo-course

tutor/templates/hooks/cms/indexcourses

@@ -1 +1,4 @@
-./manage.py cms --settings=tutor.production reindex_course --all --setup
+export DJANGO_SETTINGS_MODULE=$SERVICE_VARIANT.envs.$SETTINGS
+echo "Loading settings $DJANGO_SETTINGS_MODULE"
+
+./manage.py cms reindex_course --all --setup

tutor/templates/hooks/lms/init

@@ -1,7 +1,11 @@
 dockerize -wait tcp://{{ MYSQL_HOST }}:{{ MYSQL_PORT }} -timeout 20s
-./manage.py lms --settings=tutor.production migrate
 
-./manage.py lms --settings=tutor.production create_oauth2_client \
+export DJANGO_SETTINGS_MODULE=$SERVICE_VARIANT.envs.$SETTINGS
+echo "Loading settings $DJANGO_SETTINGS_MODULE"
+
+./manage.py lms migrate
+
+./manage.py lms create_oauth2_client \
     "http://androidapp.com" "http://androidapp.com/redirect" public \
     --client_id android --client_secret {{ ANDROID_OAUTH2_SECRET }} \
     --trusted