`ReverseProxy read error` when serving `index.html` from `/public`

[kylekeesling]

I'm having an issue when attempting to serve a file from the Rails public folder when using kamal with thruster.

I have a javascript library that requires me to copy assets to the Rails public folder so it can be accessed via the code. The path is: https://tools-demo.passtesting.com/webviewer/ui/index.html, but I get a 5xx error when attempting to access it.

When tailing the proxy logs (kamal proxy logs) I see a 301 response and then: httputil: ReverseProxy read error during body copy: unexpected EOF

When I access it as a directory (https://tools-demo.passtesting.com/webviewer/ui/) it loads as expected. The problem is that the library has a hardcoded reference to index.html instead of referring to the path, so I currently have no way to mitigate this.

The problem appears to be solved when I disable X-Sendfile (X_SENDFILE_ENABLED=false).

Ideally I'd like to keep this enabled for all of its other benefits, but is fully disabling X-Sendfile the only solution here?

[jessevdp]

Hey @kylekeesling I'm seeing the same or at least a similar issue. Did you ever figure it out?

kamal app logs
2025-02-20T08:19:07.264320841Z {"time":"2025-02-20T08:19:07.26423504Z","level":"INFO","msg":"Request","path":"/elearning/index.html","status":301,"dur":0,"method":"GET","
req_content_length":0,"req_content_type":"","resp_content_length":0,"resp_content_type":"text/html","remote_addr":"...","user_agent":"...","cache":"hit","query":""}

kamal proxy logs
2025-02-20T08:16:39.328012932Z {"time":"2025-02-20T08:16:39.327765878Z","level":"INFO","msg":"httputil: ReverseProxy read error during body copy: unexpected EOF"}

[kylekeesling]

I did not. The only workaround that worked for me was disabling X-Sendfile.

[dgm]

I hit something similar, not with kamal, but still, an index.html in the public folder ... it was only a problem with firefox. It worked ok with chrome, edge ... I was able to just remove the index.html from an iframe tag to work around it.