diff --git a/deploy_observability_service.yml b/deploy_observability_service.yml
index b6b6c90..e4132cd 100644
--- a/deploy_observability_service.yml
+++ b/deploy_observability_service.yml
@@ -118,11 +118,19 @@
       register: observability_dns_public
       until:
         - observability_dns_public.status == 200
-        - observability_dns_public.json.Status == 0
         - >
-          (observability_dns_public.json.Answer | default([])
-          | selectattr('data', 'equalto', observability_dns_target ~ '.')
-          | list | length) > 0
+          (
+            observability_dns_public.json.Status
+            if (observability_dns_public.json is defined)
+            else ((observability_dns_public.content | from_json).Status | default(1))
+          ) == 0
+        - >
+          (
+            observability_dns_public.json.Answer
+            if (observability_dns_public.json is defined)
+            else ((observability_dns_public.content | from_json).Answer | default([]))
+          ) | selectattr('data', 'equalto', observability_dns_target ~ '.')
+            | list | length > 0
       retries: "{{ dns_wait_retries }}"
       delay: "{{ dns_wait_delay }}"
 
diff --git a/roles/infra/tasks/nginx.yml b/roles/infra/tasks/nginx.yml
index 7af6356..e37939b 100644
--- a/roles/infra/tasks/nginx.yml
+++ b/roles/infra/tasks/nginx.yml
@@ -268,7 +268,7 @@
 - name: setup nginx exporter
   ignore_errors: true
   tags: nginx_exporter
-  when: nginx_exporter_enabled|bool
+  when: nginx_enabled|bool and nginx_exporter_enabled|bool
   block:
     - name: copy nginx_exporter systemd service
       template: src=nginx/nginx_exporter.svc dest={{ systemd_dir }}/nginx_exporter.service owner=root group=root mode='0644'
diff --git a/roles/node/defaults/main.yml b/roles/node/defaults/main.yml
index 01cbdb1..aaa5f76 100644
--- a/roles/node/defaults/main.yml
+++ b/roles/node/defaults/main.yml
@@ -107,7 +107,7 @@ proxy_env:                        # global proxy env when downloading packages
 #-----------------------------------------------------------------
 # NGINX (Reference)
 #-----------------------------------------------------------------
-nginx_enabled: true               # enable nginx on this infra node?
+nginx_enabled: false              # enable nginx on this infra node?
 nginx_home: /www                  # nginx content dir, `/www` by default (soft link to nginx_data)
 nginx_data: /data/nginx           # nginx actual data dir, /data/nginx by default
 #-----------------------------------------------------------------
@@ -119,4 +119,4 @@ repo_name: pigsty                 # repo name, pigsty by default
 # CA (Reference)
 #-----------------------------------------------------------------
 cert_validity: 7300d              # cert validity, 20 years by default
-...
\ No newline at end of file
+...