Use a dedicated settings file for docker devstack builds

docker/build/course_discovery/ansible_overrides.yml

 ---
 course_discovery_gunicorn_host: 0.0.0.0
 COURSE_DISCOVERY_MYSQL: 'db'
+COURSE_DISCOVERY_DJANGO_SETTINGS_MODULE: 'course_discovery.settings.devstack'
+

playbooks/roles/course_discovery/templates/edx/app/course_discovery/devstack.sh.j2

@@ -2,12 +2,7 @@
 
 # {{ ansible_managed }}
 
-cd /edx/app/edx_ansible/edx_ansible/docker/plays
-sudo ansible-playbook course_discovery.yml -c local -t 'install:app-requirements'
-sudo ansible-playbook course_discovery.yml -c local -t 'migrate:devstack' \
-                      --extra-vars="migrate_db=yes"
-sudo ansible-playbook course_discovery.yml -c local -t 'manage:devstack'
-
+source {{ course_discovery_home }}/course_discovery_env
 COMMAND=$1
 
 case $COMMAND in
@@ -15,6 +10,12 @@ case $COMMAND in
         {% set course_discovery_venv_bin = course_discovery_home + "/venvs/" + course_discovery_service_name + "/bin" %}
         {% set executable = course_discovery_venv_bin + '/gunicorn' %}
 
+        cd /edx/app/edx_ansible/edx_ansible/docker/plays
+        sudo ansible-playbook course_discovery.yml -c local -i '127.0.0.1,' \
+            -t 'install:app-requirements,assets:gather,migrate:devstack,manage:devstack' \
+            --extra-vars="migrate_db=yes" \
+            --extra-vars="@/ansible_overrides.yml"
+
         {{ executable }} -c {{ course_discovery_home }}/course_discovery_gunicorn.py \
                                  {{ COURSE_DISCOVERY_GUNICORN_EXTRA }} \
                                  --reload \