Allow custom mongodb configurations

Change-Id: I114c582181e0c58fc5b3ce5b1735fb54a0fdd93e

ansible/roles/mongodb/tasks/config.yml

@@ -27,8 +27,12 @@
     - Restart mongodb container
 
 - name: Copying over mongodb.conf
-  template:
-    src: "{{ item.key }}.conf.j2"
+  merge_configs:
+    sources:
+      - "{{ role_path }}/templates/{{ item.key }}.conf.j2"
+      - "{{ node_custom_config }}/mongodb.conf"
+      - "{{ node_custom_config }}/mongodb/{{ item.key }}.conf"
+      - "{{ node_custom_config }}/mongodb/{{ inventory_hostname }}/{{ item.key }}.conf"
     dest: "{{ node_config_directory }}/mongodb/{{ item.key }}.conf"
     mode: "0660"
   become: true