Implement sticky/persistent session with HAProxy

This commit implements sticky/persisten session between
HAProxy and Horizon based on the leastconn fashion

Related to #237
(cherry picked from commit 1a64e535b7f1a13c6ccd6388a0c95131a91f77eb)

Conflicts:
	manifests/loadbalancer.pp

manifests/dashboard.pp

@@ -138,7 +138,7 @@ class cloud::dashboard(
     server_names      => $::hostname,
     ipaddresses       => $api_eth,
     ports             => $horizon_port,
-    options           => 'check inter 2000 rise 2 fall 5'
+    options           => "check inter 2000 rise 2 fall 5 cookie ${::hostname}"
   }
 
 

manifests/loadbalancer.pp

@@ -522,6 +522,7 @@ class cloud::loadbalancer(
         'horizon_cluster':
           ports     => $horizon_port,
           httpchk   => "httpchk GET  /  HTTP/1.0\r\nUser-Agent:\ ${::hostname}",
+          options   => {'cookie' => 'sessionid prefix', 'balance' => 'leastconn' },
           listen_ip => $vip_public_ip;
       }
     }

manifests/loadbalancer/listen_http.pp

@@ -20,16 +20,19 @@
 define cloud::loadbalancer::listen_http(
   $ports     = 'unset',
   $httpchk   = 'httpchk',
+  $options   = {},
   $listen_ip = '0.0.0.0') {
 
+  $options_basic = {'mode'       => 'http',
+                    'balance'    => 'roundrobin',
+                    'http-check' => 'expect ! rstatus ^5',
+                    'option'     => ['tcpka', 'tcplog', $httpchk] }
+
+  $options_custom = merge($options_basic, $options)
+
   haproxy::listen { $name:
     ipaddress => $listen_ip,
     ports     => $ports,
-    options   => {
-      'mode'        => 'http',
-      'balance'     => 'roundrobin',
-      'option'      => ['tcpka', 'tcplog', $httpchk],
-      'http-check'  => 'expect ! rstatus ^5',
-    }
+    options   => $options_custom,
   }
 }