当无法到达上游时，使nginx忽略站点配置

我的nginx中有多个站点配置，当我重新启动计算机时，如果无法访问其中一个站点的上游，则nginx将根本无法启动，并且那些正常的站点也将无法启动，如何让Nginx会忽略那些无效的网站吗？

http {

##
# Basic Settings
##

sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
# server_tokens off;

# server_names_hash_bucket_size 64;
# server_name_in_redirect off;

include /etc/nginx/mime.types;
default_type application/octet-stream;

##
# Logging Settings
##

access_log /var/log/nginx/access.log;
error_log /var/log/nginx/error.log;

##
# Gzip Settings
##

gzip on;
gzip_disable "msie6";

# gzip_vary on;
# gzip_proxied any;
# gzip_comp_level 6;
# gzip_buffers 16 8k;
# gzip_http_version 1.1;
# gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

##
# nginx-naxsi config
##
# Uncomment it if you installed nginx-naxsi
##

#include /etc/nginx/naxsi_core.rules;

##
# nginx-passenger config
##
# Uncomment it if you installed nginx-passenger
##

#passenger_root /usr;
#passenger_ruby /usr/bin/ruby;

##
# Virtual Host Configs
##

include /etc/nginx/conf.d/*.conf;
include /etc/nginx/sites-enabled/*;
}

并且启用了sites / example1的是

upstream example1 {
    server example1.service.example.com;
}
server {
listen 80;
server_name example1.com;
location / {
    proxy_pass http://example1/;
    proxy_set_header X-Forwarded-For $remote_addr;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
}
}

并且启用了sites / example2的是

upstream example2 {
    server example2.service.example.com;
}
server {
listen 80;
server_name example2.com;
location / {
    proxy_pass http://example2/;
    proxy_set_header X-Forwarded-For $remote_addr;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
}
}

当我重新启动计算机并且那时example2.service.example.com关闭时，nginx根本不会启动，即，即使example1.service.example.com可用，nginx也不会为example1服务

===== update“关闭”的解释：所有子域都在我自己的dns服务器上自动注册/注销，因此，如果服务器关闭，则dns在尝试解析该域名时将不会响应。

最后，我找到了解决方法，解决了域insdie定位问题！

例：

server {
    listen 9000;
    server_name example1.example.com;
    location / {
        set $target http://something.service.lab.mu;
        proxy_pass http://$target;
    }
}

Nginx不会http://something.service.lab.mu在启动时尝试解决。

对于任何在此问题上绊脚石的人，@ cgcgbcbc是正确的。

但是您还需要添加一个

resolver 8.8.8.8;

指令上方

set $target http://something.service.lab.mu;

否则，您将在nginx中收到错误消息，例如：

no resolver defined to resolve