server {
  listen 3000;
  server_name _;
  root /usr/share/nginx/html;
  index index.html;

  # 由入口脚本写入：集群 DNS + A 站地址。用变量做 proxy_pass，启动时不解析上游，A 站暂不可达也不会让 nginx 起不来。
  resolver __RESOLVER__ valid=10s ipv6=off;

  location = /api/health {
    default_type text/plain;
    add_header Content-Type text/plain;
    return 200 "ok";
  }

  location /embed/ {
    set $a_upstream __A_UPSTREAM__;
    proxy_pass $a_upstream;
    proxy_http_version 1.1;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
  }

  location /images/ {
    set $a_upstream __A_UPSTREAM__;
    proxy_pass $a_upstream;
    proxy_http_version 1.1;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
  }

  location = /api/contact {
    set $a_upstream __A_UPSTREAM__;
    proxy_pass $a_upstream;
    proxy_http_version 1.1;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
  }

  location / {
    try_files $uri $uri/ /index.html;
  }
}