Nginx：未知的日志格式错误

我有一个代理设置，它使用 UDP 流量来负载平衡内部 DNS。它正在将流量正确路由到我的后端 DNS 服务器，但我似乎无法让日志格式正常工作。

我收到的错误是：

nginx[32103]: nginx: [emerg] unknown log format "dns" in /etc/nginx/nginx.conf:23

我在 http 块中有日志格式，并在stream-->server块中定义它。我试图在stream-->server块中设置 log_format，但没有一个变量可以工作。

    user www-data;
    worker_processes auto;
    pid /run/nginx.pid;
    include /etc/nginx/modules-enabled/*.conf;
    
    events {
            worker_connections 768;
            # multi_accept on;
    }
    stream {
    
      upstream dns_servers {
        least_conn;
        server 192.168.3.222:53 fail_timeout=10s;
        server 192.168.70.80:53 fail_timeout=10s;
        server 192.168.70.81:53 fail_timeout=10s;
      }
      server { 
        listen 53 udp;
        proxy_pass dns_servers;
        proxy_responses 1;
        proxy_timeout 1s;
        access_log /var/log/nginx/access.log dns;
    
      }
    }
    
    http {
    
            sendfile on;
            tcp_nopush on;
            tcp_nodelay on;
            keepalive_timeout 65;
            types_hash_max_size 2048;
    
            include /etc/nginx/mime.types;
            default_type application/octet-stream;
    
            ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE
            ssl_prefer_server_ciphers on; 
    
            log_format dns '[$time_local] | $remote_addr | $remote_user | $server_name $host to: $upstream_addr | '
                               '"$request" | $status | upstream_response_time $upstream_response_time msec '
                               '$msec | request_time $request_time';
    
            access_log /var/log/nginx/access.log dns;
            error_log /var/log/nginx/error.log;
}

我试图放置log_format在流块中，但我开始得到unknown <variable name> variable.

user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;

events {
        worker_connections 768;
        # multi_accept on;
}
stream {
 log_format dns '[$time_local] | $remote_addr | $remote_user | $server_name $host to: $upstream_addr | '
                           '"$request" | $status | upstream_response_time $upstream_response_time msec '
                           '$msec | request_time $request_time';

  upstream dns_servers {
    least_conn;
    server 192.168.3.222:53 fail_timeout=10s;
    server 192.168.70.80:53 fail_timeout=10s;
    server 192.168.70.81:53 fail_timeout=10s;
  }
  server { 
    listen 53 udp;
    proxy_pass dns_servers;
    proxy_responses 1;
    proxy_timeout 1s;
    access_log /var/log/nginx/access.log dns;

  }
}

这根本不是 Web 服务器。它只会充当 DNS 流量的代理。如何正确使日志记录正常运行？这是一个默认的 nginx.conf 文件，除了流块。