Example haproxy.cfg file for a Docker test installation of WordPress containers [http://cloudstore.interoute.com/main/knowledge-centre/blog/coreos-docker-vdc-part3]

docker_test_haproxy.cfg

global
        log 127.0.0.1   local0
        log 127.0.0.1   local1 notice
        user haproxy
        group haproxy

defaults
        log     global	
        mode    http
        option  httplog
        option  dontlognull
        option forwardfor
        option http-server-close
        contimeout 5000
        clitimeout 50000
        srvtimeout 50000
        errorfile 400 /etc/haproxy/errors/400.http
        errorfile 403 /etc/haproxy/errors/403.http
        errorfile 408 /etc/haproxy/errors/408.http
        errorfile 500 /etc/haproxy/errors/500.http
        errorfile 502 /etc/haproxy/errors/502.http
        errorfile 503 /etc/haproxy/errors/503.http
        errorfile 504 /etc/haproxy/errors/504.http
        stats enable
        stats auth username:password
        stats uri /haproxyStats

frontend http-in
        bind *:80

        # Define your hostnames
        acl wordpress_domain_1 hdr(host) -i wp1-docker.ddns.net
        acl wordpress_domain_2 hdr(host) -i wp2-docker.ddns.net
        acl wordpress_domain_3 hdr(host) -i wp3-docker.ddns.net

        ## figure out backend to use based on domainname
        use_backend wordpress1 if wordpress_domain_1 # your first registered hostname
        use_backend wordpress2 if wordpress_domain_2 # your second registered hostname
        use_backend wordpress3 if wordpress_domain_3 # your third registered hostname

backend wordpress1 # wp1-docker.ddns.net container
    balance roundrobin
    option httpclose
    option forwardfor
    server s1 172.17.0.6:80 # This ip should be the ip of the wordpress container 1

backend wordpress2 # wp2-docker.ddns.net container
    balance roundrobin
    option httpclose
    option forwardfor
    server s2 172.17.0.7:80 # This ip should be the ip of the wordpress container 2

backend wordpress3 # wp3-docker.ddns.net container
    balance roundrobin
    option httpclose
    option forwardfor
    server s3 172.17.0.8:80 # This ip should be the ip of wordpress container 3