为什么 Apache 可以实现代理传递而 nginx 却不能？

Question

我的 apache 服务器上有一个 SSL 主机，其 VirtualHost 中的内容如下：

    <VirtualHost 217.147.92.100:443>
    ServerName server.com

    ServerAdmin [email protected]
    DocumentRoot /somepath/

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
    SSLEngine on

    SSLCertificateFile  /etc/something/fullchain.pem
    SSLCertificateKeyFile /etc/something/privkey.pem

    <FilesMatch "\.(cgi|shtml|phtml|php)$">
            SSLOptions +StdEnvVars
    </FilesMatch>
    <Directory /usr/lib/cgi-bin>
            SSLOptions +StdEnvVars
    </Directory>

    BrowserMatch "MSIE [2-6]" \
            nokeepalive ssl-unclean-shutdown \
            downgrade-1.0 force-response-1.0
    # MSIE 7 and newer should be able to use keepalive
    BrowserMatch "MSIE [17-9]" ssl-unclean-shutdown

    SSLProxyEngine on
    ProxyPass "/rtapi/" "ws://localhost:38120/"
    ProxyPassReverse "/rtapi/" "ws://localhost:38120/"

    <Directory /somepath/>
        AllowOverride all
        Require all granted
    </Directory>
</VirtualHost>

到目前为止还好吗？注意 /rtapi/ 文件夹的代理密码。像往常一样，老牌 Apache 运行良好。

现在对于我们不开心的 nginx，我对它的要求就少多了：

server {
listen 45108 ssl;

ssl on;
ssl_certificate /etc/something/fullchain.pem;
ssl_certificate_key /etc/something/privkey.pem;

location / {
    proxy_pass http://localhost:38120;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
}

}

我从 nginx 寻找的只是在我的 websocket 服务上添加一个 SSL 包装器并将其代理。

我得到：

2017/08/24 19:55:01 [error] 25018#0: *2 connect() failed (111: Connection refused) while connecting to upstream, client: 71.192.225.239, server: , request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:38120/", host: "api.speedracing.tv:45108"

这似乎很有用。哦！我的小型 websocket 服务器肯定没有响应……但等一下。服务器肯定正在运行，因为它接受来自 apache 的代理请求。显然，合乎逻辑的结论是 nginx 是连接，但我真的不明白为什么或如何。