fix: 问题修复

nginx.conf

@@ -3,6 +3,9 @@ server {
     listen [::]:80;
     server_name _;
     
+    # Use Docker embedded DNS so upstream names can resolve at request time
+    resolver 127.0.0.11 ipv6=off;
+    
     root /usr/share/nginx/html;
     index index.html;
 
@@ -41,8 +44,9 @@ server {
 
     # API proxy to backend (container network)
     location /api/ {
-        # Keep original request path; backend service name resolves inside Docker network
-        proxy_pass http://backend:18888;
+        # Defer DNS resolution to avoid startup failure when backend name not yet resolvable
+        set $backend_upstream http://backend:18888;
+        proxy_pass $backend_upstream;
         proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;