filter out unused networks in docker-compose.yml template

roles/docker/templates/docker-compose.yml.j2

@@ -113,10 +113,14 @@ services:
 {% endif %}
 {% endfor %}
 
-{% if container_networks is defined %}
+{% for container in containers %}
+{% if container.service_name == item %}
+{% if container.networks is defined %}
 networks:
-{% for network in container_networks %}
-  {{ network.name }}:
+{% for network in container.networks %}
+  {{ network }}:
     external: true
 {% endfor %}
 {% endif %}
+{% endif %}
+{% endfor %}