NGINX proxy_pass删除路径前缀&解析DNS [英] NGINX proxy_pass remove path prefix & resolve DNS

问题描述

我想使用proxy_pass将请求代理到另一台服务器，同时删除匹配的路径前缀.我相信这样做的一种方法如下；

I'd like to proxy a request to another server using proxy_pass while removing the matched path prefix. I believe that one way of doing this is as follows;

location /a/ {
  proxy_pass https://website.com/
}

例如对http://localhost/a/b.html的请求将被代理到https://website.com/b.html.

E.g. a request to http://localhost/a/b.html would be proxied to https://website.com/b.html.

据我所知，NGINX上非商业版本中的问题是website.com的DNS A记录将在启动时永久加载和缓存.我已经看到一种通过在proxy_pass指令中使用诸如$request_uri之类的变量来解决此问题的技术，从而迫使NIGNX根据记录的TTL重新解析DNS.

As far as I am aware the issue with this in non-commercial versions on NGINX is that the DNS A record for website.com would be loaded and cached forever on startup. I've seen a technique to workaround this by using a variable such as $request_uri in the proxy_pass directive, thus forcing NGINX to re-resolve the DNS according to the TTL of the record.

例如

location /a/ {
  rewrite ^/a/(.*) /$1  break;
  proxy_pass https://website.com/$request_uri
}

不幸的是，上述方法似乎无效，因为它似乎仍将/a/前缀传递给上游.

Unfortunately, it seems that the above doesn't work as it seems to still pass the /a/ prefix to the upstream.

基本上，我想在这里实现的是代理请求，同时删除路径前缀，这样就不会永远缓存DNS记录.

Essentially all I want to achieve here is to proxy a request while removing the path prefix in such a way that DNS records are not cached forever.

谢谢.

推荐答案

我不确定您在哪里看到过它，但是仅专门使用$request_uri肯定不会神奇地使nginx为您解析域名动态地

I'm not sure where you've seen it, but just using specifically $request_uri is certainly not going to magically make nginx resolve the domain names for you dynamically.

假设所建议的是明确使用变量，例如$uri(这是一个不同的变量)，前提是假设使用变量时，则每次都会单独解析域名，而无需任何缓存?我不确认或否认这种假设是否正确，但是以下内容至少可以为您消除/a.

Perhaps what was suggested was explicitly using the variables, such as $uri (which is a different variable), on the assumption that when the variables are in use, then the domain name is resolved individually each time, without any caching? I don't confirm or deny whether such assumption is correct, but the following will at least get rid of /a for you.

location /a/ {
  rewrite ^/a/(.*) /$1  break;
  proxy_pass https://website.com/$uri$is_args$args;
}

(请注意，如果确实实现了不缓存域名的功能，那么您可能还希望运行本地解析器，否则，托管服务提供商的DNS的额外延迟和停机时间将立即影响您的网站，更不用说了其服务器可能的DNS查询限制.)

(Note that if it's indeed implemented not to cache the domain name, then you might as well want to run a local resolver, otherwise, the extra latency and downtime of your hosting provider's DNS will immediately affect your site, not to mention the possible DNS query limits of their servers.)

也许更好的解决方案是定期重新启动nginx以自动获取DNS中的更改?例如nginx -s reload或 kill -HUP ?如 http://nginx.org/en/docs/beginners_guide.html#control 和 http://nginx.org/en/docs/control.html#reconfiguration ，nginx永远不会停止处理任何在重新加载期间提出要求，因此应该是安全的操作；并且很可能也会导致DNS被刷新.

Perhaps a better solution would be to periodically restart nginx to automatically pick up the changes in DNS? E.g., nginx -s reload or kill -HUP? As explained in http://nginx.org/en/docs/beginners_guide.html#control and http://nginx.org/en/docs/control.html#reconfiguration, nginx never stops processing any requests during reload, so it should be a safe operation; and it'll most likely result in DNS being flushed, too.

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