Collabora Online integration issues (WOPISrc missing + socket connection error behind reverse proxy)

Description:

Hello,

I'm trying to integrate Collabora Online (CODE) with Cloudreve (Docker, pro version) using WOPI, but I’m facing two blocking issues.

Setup:

Cloudreve running in Docker behind Caddy reverse proxy
Public domain: https://console.domain.ext/
Collabora Online running in Docker (collabora/code)
Collabora exposed via Caddy on https://docs.domain.ext
Storage: Cloudflare R2 (working correctly)

Cloudreve reverse proxy (Caddy):

```
console.domain.ext {
reverse_proxy localhost:5212 {
header_up Host {host}
header_up X-Forwarded-Proto {scheme}
header_up X-Forwarded-Host {host}
}
}

```
Collabora setup:

```
docker run -d \
--name collabora \
-p 127.0.0.1:9980:9980 \
-e "aliasgroup1=https://console.domain.ext" \
-e "domain=console\\.domain\\.ext" \
-e "extra_params=--o:ssl.enable=false --o:ssl.termination=true" \
collabora/code
```

Issues:

WOPI error in Collabora

When opening a document:

Wrong or missing WOPISrc parameter

It seems Collabora is not receiving a valid WOPISrc URL from Cloudreve.

WebSocket / reverse proxy error

Collabora frontend shows:

Failed to establish socket connection or socket connection closed unexpectedly. The reverse proxy might be misconfigured.

Observations:

Cloudreve backend is working correctly (upload/download OK)
API /api/v4/file/content works fine
No database or storage errors
The issue only happens when opening documents in Collabora

Question:

Could you clarify:

- How Cloudreve generates the WOPISrc URL (is it based on SiteURL or request headers)?
- What is the recommended reverse proxy configuration for WOPI + Collabora behind Caddy/Nginx?
- Are there any required environment variables to force external base URL for WOPI?
- Any known issues with Docker + reverse proxy causing localhost WOPISrc generation?