feat: add support for X-Forwarded-Port in ProxyFix middleware

[osaimi]

Summary

Updated ProxyFix middleware to include x_port=1 for handling the X-Forwarded-Port header. Improved the description of RESPECT_XFORWARD_HEADERS_ENABLED for clarity.

I couldn't find RESPECT_XFORWARD_HEADERS_ENABLED in the Dify Document. Please advise if documentation should be added.

Fixes #13070

Screenshots

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Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[laipz8200]

Hi, @kurokobo. Could you please take a look at this PR about X-Forward?

[kurokobo]

@osaimi
Hi, thanks for sending the PR.
Have you tested your PR on your side with the official docker-compose.yaml?

I haven't test this yet but since the current Nginx configuration does not set the header X-Forwarded-Port, so I don't think simply adding x_port=1 will satisfy your requirement:

dify/docker/nginx/proxy.conf.template

Lines 4 to 5 in b05e9d2

	proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
	proxy_set_header X-Forwarded-Proto $scheme;

In addition, since Nginx is running as a container under Docker network, it seems that some modification is required to set the expected port number to the X-Forwarded-Port.

Even if you are not using the Nginx included in the official compose file, if you want this PR to be merged, I think any changes should work well with the official compose file.

@laipz8200
Thanks for sharing this with me!

[osaimi]

@kurokobo you're right. I'm using my own Nginx config, but it should work out of the box for those using the default Nginx container and needing to modify the ports. I'll add support for the X-Forwarded-Port header in Dify's Nginx.