Caddy: proxy: twin websocket connections?

[edrex]

Companion issue: https://github.com/emersion/net-browserify/issues/7

It appears to be relevant that Caddy opens two websocket connections rather than one.

[mholt]

It opens two? How came you by this?

[edrex]

well, the backend server logs two connections (see linked issue). Wireshark also shows two HTTP connections to the socket, along with lots of DUP ACKs. I hesitate to post the wireshark dump since

[mholt]

Haha.

I do not see any information about the backend logging two connections in the linked issue -- can you link me to it directly? I must be blind!

[edrex]

I was curious if this was always happening and just some backend servers are tolerant of it, so I tried it with the loop example and sure enough, wireshark sees two socket connections.

[edrex]

Here is a shot from wireshark only showing http and websocket frames:

Frames <= 27 are direct, and frames > 40 are through the proxy. Note the duplicate requests in the second group.

[edrex]

@mholt I realized I hadn't posted the log on the linked issue, but I think the evidence above is clearer.

[klingtnet]

Maybe this is related to my issue running a jupyter notebook server with caddy acting as a reverse proxy. Websocket connections are working when I access the server directly using SSH portforwarding ssh -L 12345:localhost:12345 host but there are sporadic issues when connecting through caddy (sometimes it works, sometimes don't). I haven't figured out the problem yet because jupyters log does not show any error, so I also have to record the traffic with wireshark.

Caddy config:

jupyter.klingt.net {
    proxy / localhost:10180 {
        proxy_header Host {host}
        proxy_header X-Real-IP {remote}
        proxy_header X-Forwarded-Proto {scheme}
        websocket
    }
}

[edrex]

@klingtnet yeah, most likely. Stay tuned, fix in progress.

[mholt]

@edrex How's it coming? Anything I can help with? Since Go 1.6.2 was released last night, we can release a new version of Caddy to great benefit. Definitely want to make sure this fix gets in there.

[edrex]

On the road for a conf. Looked at this for an hour yesterday, made some progress but didn't get it working. Hope to get some hack time today

[edrex]

Continuing on #764

[nemosupremo]

Fixed by #987

[klingtnet]

Jupyter notebooks are running fine with caddy 0.9.1!
Thanks to all of you for your efforts to fix this bug!