Re-add dependency of nginx to lms/cms

We re-introduce the dependency of the nginx container on the lms/cms
images. This dependency was removed to address a debugging scenario
which is actually not practical. Without this dependency, we are forced
to use an external docker-specific resolver which makes the local nginx
configuration incompatible with the kubernetes configuration.

deploy/local/templates/docker-compose.yml

@@ -47,6 +47,10 @@ services:
       - ../env/nginx:/etc/nginx/conf.d/
       - ../../data/openedx:/var/www/openedx:ro
       - ../../data/letsencrypt:/etc/letsencrypt/:ro
+    depends_on:
+      - lms
+      - cms
+      {% if ACTIVATE_NOTES %}- notes{% endif %}
 
   rabbitmq:
     image: rabbitmq:3.6.10

deploy/templates/nginx/cms.conf

@@ -1,3 +1,7 @@
+upstream cms-backend {
+    server cms:8000 fail_timeout=0;
+}
+
 {% if ACTIVATE_HTTPS %}
 server {
     server_name {{ CMS_HOST }};
@@ -31,10 +35,7 @@ server {
     proxy_set_header Host $http_host;
     proxy_redirect off;
 
-    # Docker resolver
-    resolver 127.0.0.11 valid=10s;
-    set $upstream cms;
-    proxy_pass http://$upstream:8000;
+    proxy_pass http://cms-backend;
   }
 
   location / {

deploy/templates/nginx/extra.conf

@@ -1,4 +1,8 @@
 {% if ACTIVATE_NOTES %}
+upstream notes-backend {
+    server notes:8000 fail_timeout=0;
+}
+
 {% if ACTIVATE_HTTPS %}
 server {
     server_name notes.{{ LMS_HOST }};
@@ -26,10 +30,7 @@ server {
     proxy_set_header Host $http_host;
     proxy_redirect off;
 
-    # Docker resolver
-    resolver 127.0.0.11 valid=10s;
-    set $upstream notes;
-    proxy_pass http://$upstream:8000;
+    proxy_pass http://notes-backend:8000;
   }
 }
 {% endif %}

deploy/templates/nginx/lms.conf

@@ -1,3 +1,7 @@
+upstream lms-backend {
+    server lms:8000 fail_timeout=0;
+}
+
 {% if ACTIVATE_HTTPS %}
 server {
     server_name {{ LMS_HOST }} preview.{{ LMS_HOST }};
@@ -31,10 +35,7 @@ server {
     proxy_set_header Host $http_host;
     proxy_redirect off;
 
-    # Docker resolver
-    resolver 127.0.0.11 valid=10s;
-    set $upstream lms;
-    proxy_pass http://$upstream:8000;
+    proxy_pass http://lms-backend;
   }
 
   location / {