Websocket shim is not getting injected to the response if accept encoding header is present

[pkvprakash]

Websocket shim code is not getting injected if Accept-Encoding header is present with the request.

Response when Accept-Encoding header is present with the request:

Response when Accept-Encoding header is not present in the request:

[ojarjur]

My guess is that the response body is being sent back compressed (due to the Accept-Encoding header being set to gzip, deflate, br).

The code in the proxy agent that injects the shim code does not support decompressing/recompressing it, so compressed responses just get sent back as-is.

That is something that we are unlikely to support directly as the added complexity of decompressing/recompressing the output is probably not worth the added benefit.

It would be better to instead disable the compressed responses from your backend server; either directly (if your server supports that), or via a proxy that drops this header when the Accept header is text/html.

However, the best option would be to just support websocket directly instead of requiring the shim code injection.

For the case of the Inverting Proxy server, that could be implemented here, by converting the shim logic from Javascript to Go.

I'd be open to any pull requests that added that.

If you were to use the AppEngine version of the proxy that would not help you (since AppEngine does not support websocket), but from your screenshots it looks like you are not doing that.