loadbalancer: Implementing a proper failover based on the router state

Due to the fact that two HAProxy can not listen on the same vip at the
same time, the management of the HAProxy service has been delegated to
the keepalived process. With this patch, the keepalived process
starts/stops the HAProxy daemon based on the state is is entering.

If it enters MASTER mode then it starts the HAProxy daemon.
If it enters BACKUP mode then it stops the HAProxy daemon.

close #25

manifests/loadbalancer.pp

@@ -56,7 +56,9 @@ class cloud::loadbalancer(
   $mysql_vip                      = $os_params::mysql_vip
 ){
 
-  class { 'haproxy': }
+  class { 'haproxy':
+    manage_service => false,
+  }
 
   class { 'keepalived': }
 
@@ -65,11 +67,13 @@ class cloud::loadbalancer(
   }
 
   keepalived::instance { '1':
-    interface         => $keepalived_interface,
-    virtual_ips       => split(join(flatten([$keepalived_ipvs, ['']]), " dev ${keepalived_interface},"), ','),
-    state             => $keepalived_state,
-    track_script      => ['haproxy'],
-    priority          => 50,
+    interface     => $keepalived_interface,
+    virtual_ips   => split(join(flatten([$keepalived_ipvs, ['']]), " dev ${keepalived_interface},"), ','),
+    state         => $keepalived_state,
+    track_script  => ['haproxy'],
+    priority      => 50,
+    notify_master => '"/etc/init.d/haproxy start"',
+    notify_backup => '"/etc/init.d/haproxy stop"',
   }
 
   $monitors_data = inline_template('

spec/classes/cloud_loadbalancer_spec.rb

@@ -63,7 +63,9 @@ describe 'cloud::loadbalancer' do
     end
 
     it 'configure haproxy server' do
-      should contain_class('haproxy')
+      should contain_class('haproxy').with({
+        'manage_service' => 'false',
+      })
     end
 
     it 'configure keepalived server' do
@@ -72,7 +74,9 @@ describe 'cloud::loadbalancer' do
 
     it 'configure vrrp_instance with MASTER state' do
       should contain_keepalived__instance('1').with({
-        'state' => 'MASTER',
+        'state'         => 'MASTER',
+        'notify_master' => '"/etc/init.d/haproxy start"',
+        'notify_backup' => '"/etc/init.d/haproxy stop"',
       })
     end
 
@@ -121,7 +125,9 @@ describe 'cloud::loadbalancer' do
     end
 
     it 'configure haproxy server' do
-      should contain_class('haproxy')
+      should contain_class('haproxy').with({
+        'manage_service' => 'false',
+      })
     end
 
     it 'configure keepalived server' do
@@ -129,7 +135,10 @@ describe 'cloud::loadbalancer' do
     end
 
     it 'configure vrrp_instance with BACKUP state' do
-      should contain_keepalived__instance('1')
+      should contain_keepalived__instance('1').with({
+        'notify_master' => '"/etc/init.d/haproxy start"',
+        'notify_backup' => '"/etc/init.d/haproxy stop"',
+      })
     end
 
   end