当你的nginx服务器和php服务器不在一起的时候，这个nginx 的root目录问题

server {
listen 80 default_server;
listen [::]:80 default_server;

    # SSL configuration
    #
    # listen 443 ssl default_server;
    # listen [::]:443 ssl default_server;
    #
    # Note: You should disable gzip for SSL traffic.
    # See: https://bugs.debian.org/773332
    #
    # Read up on ssl_ciphers to ensure a secure configuration.
    # See: https://bugs.debian.org/765782
    #
    # Self signed certs generated by the ssl-cert package
    # Don't use them in a production server!
    #
    # include snippets/snakeoil.conf;
    #尽管说不影响后面的php目录但是还是要设置，否则nginx工作不正常
    root /var/www/html;

    # Add index.php to the list if you are using PHP
    index index.php index.html index.htm index.nginx-debian.html;

    server_name 10.8.125.86;

    location / {
            # First attempt to serve request as file, then
            # as directory, then fall back to displaying a 404.
            try_files $uri $uri/ =404;
    }

    # pass PHP scripts to FastCGI server

    location ~ \.php$ {
            #include snippets/fastcgi-php.conf;
    #
    #       # With php-fpm (or other unix sockets):
    #       fastcgi_pass unix:/run/php/php7.4-fpm.sock;
    #       # With php-cgi (or other tcp sockets):
            fastcgi_pass 172.17.0.2:9000;
            fastcgi_index index.php;
            #php服务器会根据这个地址来查找网站代码
            fastcgi_param SCRIPT_FILENAME /var/www/html/$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;
    #}

}