Replay/test the initial registration handshake between Cattle node agent and Rancher server

agent-register-handshake.sh

#!/bin/bash
# Execute this script in a cattle-node-agent container
# Successful websocket handshake is indicated by following line being printed:
# HTTP/1.1 101 Switching Protocols

TOKEN=$(cat /cattle-credentials/token)
URL="$(cat /cattle-credentials/url)/v3/connect/register"

echo "Using TOKEN: $TOKEN"
echo "Using URL: $URL"

read -r -d '' PARAMS_JSON << EOF
{
  "Node": {
          "customConfig": {
            "address": "8.8.8.8",
            "roles": [
            ],
            "labels": [
            ]
          },
          "etcd": false,
          "controlPlane": false,
          "worker": false,
          "requestedHostname": "hostname1"
}
}
EOF

echo "Using PARAMS:"
echo "$PARAMS_JSON"

PARAMS_BASE64=$(echo "$PARAMS_JSON" | base64 -w0)

#docker run --net=host appropriate/curl -i -N \

curl -v -i -N --http1.1 \
        -H "Connection: Upgrade" \
        -H "Upgrade: websocket" \
        -H "Sec-WebSocket-Key: SGVsbG8sIHdvcmxkIQ==" \
        -H "Sec-WebSocket-Version: 13" \
        -H "X-API-Tunnel-Token: $TOKEN" \
        -H "X-API-Tunnel-Params: $PARAMS_BASE64" \
        -k $URL

I'm trying to debug an issue in Rancher (rancher/rancher#17617), and found this gist. Would you happen to know the curl equivalent of an agent already registered connecting to rancher?

time="2019-08-08T14:36:05Z" level=info msg="Connecting to wss://rancher.domain/v3/connect with token atoken"
time="2019-08-08T14:36:05Z" level=info msg="Connecting to proxy" url="wss://rancher.domain/v3/connect"
time="2019-08-08T14:36:14Z" level=info msg="Starting plan monitor"
time="2019-08-08T14:36:19Z" level=debug msg="Wrote ping"
time="2019-08-08T14:36:24Z" level=debug msg="Wrote ping"
time="2019-08-08T14:36:24Z" level=error msg="Failed to connect to proxy" error="read tcp machine_ip:59454->rancher_ip:443: i/o timeout"