map $msec $sample_200 {
    default 0;
    "~00$" 1;  # 每 200 次大约打印 1 次
}

map $http_user_agent $loggable {
    default 1;
    "clb-healthcheck" $sample_200;
}

log_format custom_main '$remote_addr - $remote_user [$time_local+0800] "$request" '
                   '$status $body_bytes_sent "$http_referer" '
                   '"$http_user_agent" rt=$request_time ua="$upstream_addr" '
                   'us="$upstream_status" ut="$upstream_response_time"';

server {
    listen 80;
    server_name _;

        access_log /var/log/nginx/access.log custom_main if=$loggable;

    # 前端静态文件
    location / {
        root /usr/share/nginx/html;
        index index.html;
        try_files $uri $uri/ /index.html;
    }


    # 精确匹配 index.html，禁用缓存
    location = /index.html {
        root /usr/share/nginx/html;
        add_header Cache-Control "no-cache, no-store, must-revalidate";
    }

    # 静态资源开启长缓存（带 hash）
    location ~* \.(js|css|woff2|json|svg|png|jpg|jpeg|gif|ico|ttf|otf|eot|mp4|webm|webp)$ {
        root /usr/share/nginx/html;
        add_header Cache-Control "public, max-age=31536000, immutable";
        access_log off;
    }
}