HAProxy + WebSocket Disconnection

Question

I am using HAProxy to send requests, on a subdomain, to a node.js app.

I am unable to get WebSockets to work. So far I have only been able to get the client to establish a WebSocket connection but then there is a disconnection which follows very soon after.

I am on ubuntu. I have been using various versions of socket.io and node-websocket-server. The client is either the latest versions of Safari or Chrome. HAProxy version is 1.4.8

Here is my HAProxy.cfg

global 
    maxconn 4096 
    pidfile /var/run/haproxy.pid 
    daemon 

defaults 
    mode http 

    maxconn 2000 

    option http-server-close
    option http-pretend-keepalive

    contimeout      5000
    clitimeout      50000
    srvtimeout      50000

frontend HTTP_PROXY
    bind *:80 

    timeout client  86400000

    #default server
    default_backend NGINX_SERVERS

    #node server
    acl host_node_sockettest hdr_beg(host) -i mysubdomain.mydomain

use_backend NODE_SOCKETTEST_SERVERS if host_node_sockettest


backend NGINX_SERVERS 
server THIS_NGINX_SERVER 127.0.0.1:8081

backend NODE_SOCKETTEST_SERVERS
timeout queue   5000
timeout server  86400000

server THIS_NODE_SERVER localhost:8180 maxconn 200 check

I've trawled the web and mailing list but can not get any of the suggested solutions to work.

(p.s. this could be for serverfault, but there are other HAProxy question on S.O, so I have chosen to post here)

Answer 1

Upgrade to latest version of socket.io (0.6.8 -> npm install socket.io@0.6.8, which is patched to work with HAProxy) and download the latest version of HAProxy.

Here is an example config file:

global
    maxconn     4096 # Total Max Connections. This is dependent on ulimit
    nbproc      2

defaults
    mode        http

frontend all 0.0.0.0:80
    timeout client 5000
    default_backend www_backend
    acl is_websocket hdr(Upgrade) -i WebSocket
    acl is_websocket hdr_beg(Host) -i ws

    use_backend socket_backend if is_websocket

backend www_backend
    balance roundrobin
    option forwardfor # This sets X-Forwarded-For
    timeout server 5000
    timeout connect 4000
    server server1 localhost:8081 weight 1 maxconn 1024 check
    server server2 localhost:8082 weight 1 maxconn 1024 check
    server server3 localhost:8083 weight 1 maxconn 1024 check

backend socket_backend
    balance roundrobin
    option forwardfor # This sets X-Forwarded-For
    timeout queue 5000
    timeout server 5000
    timeout connect 5000
    server server1 localhost:8081 weight 1 maxconn 1024 check
    server server2 localhost:8082 weight 1 maxconn 1024 check
    server server3 localhost:8083 weight 1 maxconn 1024 check

Answer 2

It's likely that your client is using WebSockets version 76. In which case you can't use "mode http" because the WebSockets handshake violates HTTP. There seems to be ambivalence in the committee about whether the WebSockets handshake should be compatible with HTTP or not. Anyways, the problem with the v76 handshake is that raw data is sent with the handshake (the checksum chunk).

The relevant HAProxy discussion: http://www.mail-archive.com/haproxy@formilux.org/msg03046.html

From the discussion it sounds like there might be a way to default to TCP mode and fall back to HTTP for non-WebSockets connections.

Answer 3

We are using a Netty implementation https://github.com/ibdknox/socket.io-netty and here is the HAProxy file that worked for us. The trick to get it not to fall back to XHR-Polling but use Websockets is putting HAProxy into TCP mode. HAProxy config:

global
    daemon
    maxconn 32000

defaults
    mode http
    timeout connect 5000ms
    timeout client 50000ms
    timeout server 50000ms

listen http-in
    bind *:80
    server server1 1.1.1.1:8000 check
    server server2 1.1.1.1:8000 check

listen socketio-in
    mode tcp
    bind *:8080
    balance source
    timeout queue 5000
    timeout server 86400000
    timeout connect 86400000
    server server1 1.1.1.1:8080 check
    server server2  1.1.1.1:8080 check

Where 1.1.1.1 is your IPs

Answer 4

Try using Socket.io instead of node-websockets-server, it's an abstraction layer with fallbacks to many different methods of instant communication between browser and server.

Whilst it's true WebSockets violate HTTP 1.0, they do not violate HTTP 1.1, so you should be able to proxy them with any server capable of proxying HTTP 1.1