在同一目录下Nginx对多个配置文件的读取顺序问题

首先，说明结论：同一目录下存在多个配置文件时，Nginx是按照文件的名称先后顺序依次读取的！

背景：

Nginx做反向代理时，可能需要代理多个服务器，这时，有一种可行的方案就是将不同的代理服务器配置在不同的配置文件中，如：

[root@localhost conf.d]# pwd
/mydata/nginx/conf/conf.d
[root@localhost conf.d]# ls
default.conf  orderSys.conf  productSys.conf

三个配置文件的内容分别为：

[root@localhost conf.d]# cat default.conf 
server {
    listen       80;
    server_name  localhost;

    #charset koi8-r;
    #access_log  /var/log/nginx/log/host.access.log  main;

    location / {
        root   /usr/share/nginx/html;
        index  index.html index.htm;
    }

    #error_page  404              /404.html;

    # redirect server error pages to the static page /50x.html
    #
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }

    # proxy the PHP scripts to Apache listening on 127.0.0.1:80
    #
    #location ~ \.php$ {
    #    proxy_pass   http://127.0.0.1;
    #}

    # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
    #
    #location ~ \.php$ {
    #    root           html;
    #    fastcgi_pass   127.0.0.1:9000;
    #    fastcgi_index  index.php;
    #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
    #    include        fastcgi_params;
    #}

    # deny access to .htaccess files, if Apache's document root
    # concurs with nginx's one
    #
    #location ~ /\.ht {
    #    deny  all;
    #}
}

[root@localhost conf.d]# cat orderSys.conf 
server {
    listen       80;
    server_name  order.com;

    location / {
		proxy_set_header Host $host;
        proxy_pass http://order;
    }
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }
}

[root@localhost conf.d]# cat productSys.conf 
server {
    listen       80;
    server_name  product.com;

    location / {
		proxy_set_header Host $host;
        proxy_pass http://product;
    }
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }
}

此处再次强调，Nginx是按照文件的名称先后顺序读取的！
因此，如果default.conf、orderSys.conf、productSys.conf三个文件代理的内容有优先级，则需要根据优先级排列三个配置。必要的时候，可以通过命名规则排序，如：01-default.conf、02-productSys.conf、03-orderSys.conf。避免因为顺序不当导致代理结果异常，最终导致访问异常，如下所示：

Whitelabel Error Page
This application has no configured error view, so you are seeing this as a fallback.

Thu Feb 18 23:26:40 CST 2021
[84e87484-818] There was an unexpected error (type=Not Found, status=404).