Add subnet configuratin to Docker Compose to avoid conflicts.

The out of the box subnet Docker Compose selects may conflict with your existing LAN subnets. This makes it configurable.

installer/inventory

@@ -154,3 +154,6 @@ secret_key=awxsecret
 # which makes include "optional" - i.e. not fail
 # if file is absent
 #extra_nginx_include="/etc/nginx/awx_extra[.]conf"
+
+# Docker compose explicit subnet. Set to avoid overlapping your existing LAN networks.
+#docker_compose_subnet="172.17.0.1/16"

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

@@ -171,6 +171,17 @@ services:
       https_proxy: {{ https_proxy | default('') }}
       no_proxy: {{ no_proxy | default('') }}
   {% endif %}
+
+{% if docker_compose_subnet is defined %}
+networks:
+  default:
+    driver: bridge
+    ipam:
+      driver: default
+      config:
+      - subnet:  {{ docker_compose_subnet }}
+{% endif %}
+
 volumes:
   supervisor-socket:
   rsyslog-socket: