support for external_links
diff --git a/xos/synchronizers/onboarding/templates/docker-compose.yml.j2 b/xos/synchronizers/onboarding/templates/docker-compose.yml.j2
index fa05397..faa9d02 100644
--- a/xos/synchronizers/onboarding/templates/docker-compose.yml.j2
+++ b/xos/synchronizers/onboarding/templates/docker-compose.yml.j2
@@ -18,6 +18,12 @@
     - {{ link }}
 {%- endfor %}
 {%- endif %}
+{%- if container.external_links %}
+  external_links:
+{%- for link in container.external_links %}
+    - {{ link }}
+{%- endfor %}
+{%- endif %}
 {%- if container.volumes %}
   volumes:
 {%- for volume in container.volumes %}