Add load balancer configuration example

Author: ain

README.md

@@ -50,11 +50,13 @@ set :docker_compose_user, '<username>'
 # Define port range in respect to load balancer on server
 # If 2 or more environments reside on same server, configure port range as per environment
 # Ruby's Range object is expected, see http://ruby-doc.org/core-2.3.0/Range.html
-# Example: set :docker_compose_port_range, 2070..2080
+# Example: set :docker_compose_port_range, 2070..2071
 set :docker_compose_port_range, <port>..<port>
 ```
 
-Configure load balancer on server using port range defined in `docker_compose_port_range`.
+Configure load balancer with port range defined in `docker_compose_port_range`, see [example configuration](https://github.com/interactive-pioneers/capistrano-docker-compose/blob/master/haproxy.example.cfg).
+
+NB! Ensure load balancer's HTTP health check uses Layer 7 and corresponds to the needs of the particular application.
 
 ## Contributing
 

haproxy.example.cfg

@@ -0,0 +1,42 @@
+global
+	log /dev/log	local0
+	log /dev/log	local1 notice
+	chroot /var/lib/haproxy
+	user haproxy
+	group haproxy
+	daemon
+
+defaults
+	log	global
+	mode	http
+	option	httplog
+	option	dontlognull
+	option http-server-close
+	option redispatch
+  timeout connect 5000
+	timeout http-keep-alive 15s
+  timeout server 50000
+  timeout client 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
+
+frontend http-in
+	bind *:80
+	mode http
+	acl my_domain_control hdr(host) -i my-domain.com
+ 	use_backend containers if my_domain_control
+
+backend containers
+	mode http
+	balance roundrobin
+	option forwardfor
+	option httpchk get /
+	http-check expect ! rstatus ^5
+	default-server fall 1 rise 1
+	server container1 127.0.0.1:2070 observe layer7
+	server container2 127.0.0.1:2071 observe layer7