关于Nginx中路由报错 no resolver defined to resolve localhost

该问题是由动态解析造成的
比如下面的配置： > 该路由规则 proxy_pass 后面跟的是变量，当该位置是变量的时候Nginx会在每个请求中动态解析localhost, 而这就会导致resolver错误

        location ~ ^/k8sapi(/(.*))?$ {
            proxy_set_header    Host  $host;
            proxy_set_header    X-Real-IP  $remote_addr;
            proxy_set_header    X-Forwarded-For  $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_redirect off;
            proxy_pass https://localhost:6443/$2;
        }

而如果是静态解析
比如下面的配置： > proxy_pass 后面跟的是一个具体的值，该值会被硬编码到proxy_pass指令中，只会在Nginx启动的时候解析一次，并且缓存结果；那么这种方式就不会报错

        location ~ ^/k8sapi(/(.*))?$ {
            proxy_set_header    Host  $host;
            proxy_set_header    X-Real-IP  $remote_addr;
            proxy_set_header    X-Forwarded-For  $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_redirect off;
            proxy_pass https:localhost:6443/;
        }

How do I fix the problem? Two scenarios:
- 1. Add a line to the routing rule

    location ~ ^/k8sapi(/(.*))?$ {
        resolver 127.0.0.1;  # 添加这一行
        proxy_set_header    Host  $host;
        proxy_set_header    X-Real-IP  $remote_addr;
        proxy_set_header    X-Forwarded-For  $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_redirect off;
        proxy_pass https://localhost:6443/$2;
    }