Check websocket connection (eg. from monitoring software)

websocket.sh

#!/bin/bash
#
# Check a websocket connection with curl. Pass URL to check as parameter.
# In normal conditions, this should return a 101 (Switching protocol).
#

CODE=$(timeout 3 curl -s --http1.1 \
     --include \
     --no-buffer \
     --header "Connection: Upgrade" \
     --header "Upgrade: websocket" \
     --header "Sec-WebSocket-Key: VGhhbmsgeW91IFRvbUNhbiE=" \
     --header "Sec-WebSocket-Version: 13" \
     $1 | grep -Eo "HTTP/1.1 [0-9]{3}" | grep -Eo "[0-9]{3}")

if [ "$CODE" != "" ]
then
    # we got a HTTP status code
    echo $CODE
else
    # return return value of the command
    echo $?
fi