Here's a sample WORKING haproxy config for websockets / socketio. We were able to get socketio working on an Amazon ELB with just one node, but when we added multiple nodes, we saw weird client issues. So, we decided to use HAProxy on Ubuntu 12.04 and spent significant time trying to get just the right configuration (haproxy.cfg). Note though th…

haproxy.cfg

global
	#debug
	#daemon
	log 		        127.0.0.1    local0

  defaults
	log  		        global
	option 		        httplog

  frontend unsecured *:80
	mode 		        http
	timeout 		client 86400000
	redirect 		prefix https://[ha-hostname] code 301 

  frontend  secured
	bind			0.0.0.0:443 ssl crt /path/to/your/cert/chain.pem
	mode			tcp
	log			global
	option			tcplog
	timeout			client   3600s
	backlog			4096
	maxconn			50000      
	default_backend		www_backend

  backend www_backend
        mode  		        tcp
        option 		        log-health-checks
        option 		        redispatch
        option 		        tcplog
        balance 	        source
	timeout 	        connect   1s
        timeout             	queue     5s
        timeout 	        server    3600s
	
      	#SERVERBEGIN
      	     server     websocket-001 websocket-001.domain.com:8080 maxconn 1000 weight 10 check
             server     websocket-002 websocket-002.domain.com:8080 maxconn 1000 weight 10 check
             server     websocket-003 websocket-003.domain.com:8080 maxconn 1000 weight 10 check
      	#SERVEREND

  listen stats 0.0.0.0:8888
        mode            	http
        stats           	enable
        option          	httplog
        stats           	show-legends
        stats          		uri /haproxy
        stats           	realm Haproxy\ Statistics
        stats           	refresh 5s
        stats           	auth SECRETUSER:SECRETPASS
        timeout         	connect 5000ms
        timeout         	client 50000ms
        timeout         	server 50000ms

update_haproxy_config.sh

#/bin/bash
############################################################################################
## Assumptions:
##    - The EC2 Name on your instance for the haproxy is simply "haproxy.domain.com"
##    - Your member servers are named "websocket-001.domain.com .. websocket-999.domain.com
##    - Your using VPCs and yoru haproxy sits in the public subnet with an EIP
##    - Your websocket servers are listening on 8080
##
## Your root crontab entry could look like this (run every 15 min):
##    */15 * * * * /path/to/update_haproxy_config.sh > /dev/null 2>&1
## 
############################################################################################

export EC2_CERT=/path/to/your/ec2/cert.pem
export EC2_PRIVATE_KEY=/path/to/your/ec2/pk.pem
MAXCONN=1000
TMPTAGFILE=/tmp/websocket_tags
TMPINSTANCES=/tmp/websocket_instances
TMPHOSTS=/tmp/hosts
TMPHACONFIG=/tmp/testconfig
HACONFIG=/etc/haproxy/haproxy.cfg
HACONFIGSERVERS=/tmp/haconfig
echo "" > $HACONFIGSERVERS
echo "" > $TMPHOSTS
echo "" > $HACONFIGSERVERS

##################################################################
## Query the AWS EC2 API looking for servers named "socketio"
## You can adjust this if you want to name your member servers
## something different
##################################################################

echo "Getting EC2 Data..."
ec2-describe-tags | grep Name | grep websocket | grep -v haproxy > $TMPTAGFILE
ec2-describe-instances | grep INSTANCE  > $TMPINSTANCES
while read line; do
    NAME1=`echo $line | awk '{print $5}' | tr '.' ' ' | awk '{print $1}'`
    NAME2=`echo $line | awk '{print $5}'`
    INSTANCEID=`echo $line | awk '{print $3}'`
    INTERNALIP=`cat $TMPINSTANCES | grep $INSTANCEID | awk '{print $15}'`
    echo  "$INTERNALIP   $NAME1    $NAME2" >> $TMPHOSTS
    echo  "     server     $NAME1 $NAME2:8080 maxconn $MAXCONN weight 10 check" >> $HACONFIGSERVERS
    echo "" >> $HACONFIGSERVERS
done < $TMPTAGFILE

#############################################################
## this modifies the /etc/hosts file so we can
## use the internal ip (10.x.x.x) for traffic rather then
## then EIP
#############################################################
if [ `cat $TMPHOSTS | wc -l` -gt 0 ]; 
then
  echo "Writing New Host File..."
	echo "127.0.0.1    localhost   haproxy  haproxy.domain.com" > /etc/hosts
	cat $TMPHOSTS | sed '/^$/d' | sort -k 2  >> /etc/hosts
fi

#############################################################
##  This rewrites the haproxy.cfg file placing additional 
##  servers between the two blocks:
##      #SERVERBEGIN
##          ....
##      #SERVEREND
##
##  And then reloads the config
#############################################################
if [ `cat $HACONFIGSERVERS | wc -l` -gt 0 ]; 
then
	echo "Writing HA Proxy Config File..."
	SUBSERVER=`cat $HACONFIGSERVERS | sort -u | sed '/^$/d' | sed -e 's/[\/&]/\\&/g'`
	cat $HACONFIG | sed -e "/#SERVERBEGIN/,/#SERVEREND/c\\\t\#SERVERBEGIN\n\tSERVERPLACEHOLDER\n\t\#SERVEREND" | perl -p -i -e "s/SERVERPLACEHOLDER/${SUBSERVER}/g" > $TMPHACONFIG
	cat $TMPHACONFIG > $HACONFIG

	echo "Reloading HAProxy..."
	/etc/init.d/haproxy reload
fi

#############################################################
##  file cleanup
#############################################################
rm -f $TMPTAGFILE
rm -f $TMPINSTANCES
rm -f $HACONFIGSERVERS
rm -f $TMPHOSTS
rm -f $TMPHACONFIG

Did you also have these errors:
miguelgrinberg/microflack_admin#6
socketio/socket.io#1942

Why do you use three of these?

 	#SERVERBEGIN
  	     server     websocket-001 websocket-001.domain.com:8080 maxconn 1000 weight 10 check
         server     websocket-002 websocket-002.domain.com:8080 maxconn 1000 weight 10 check
         server     websocket-003 websocket-003.domain.com:8080 maxconn 1000 weight 10 check
  	#SERVEREND

is this the trick?