From b8bb7cc4234d56cd25b17a84a5eecc245b0136a9 Mon Sep 17 00:00:00 2001
From: Digimer <digimer@alteeve.ca>
Date: Thu, 25 Aug 2022 12:43:51 -0400
Subject: [PATCH] * Changed the default trigger of live migrations to require a
 health score difference of 2 or higher. This can be user-adjusted using the
 new 'feature::scancore::threshold::preventative-live-migration' anvil.conf
 option.

Signed-off-by: Digimer <digimer@alteeve.ca>
---
 Anvil/Tools.pm          | 10 ++++++++++
 Anvil/Tools/ScanCore.pm | 14 +++++++++++++-
 share/words.xml         |  8 +++++++-
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/Anvil/Tools.pm b/Anvil/Tools.pm
index 2335d59b..c82b803f 100644
--- a/Anvil/Tools.pm
+++ b/Anvil/Tools.pm
@@ -1009,6 +1009,16 @@ sub _set_defaults
 			html		=>	"alteeve",
 		},
 	};
+	$anvil->data->{feature} = {
+		scancore	=>	{
+			disable		=>	{
+				'preventative-live-migration'	=>	0,
+			},
+			threshold	=>	{
+				'preventative-live-migration'	=>	2,
+			},
+		},
+	};
 	
 	return(0);
 }
diff --git a/Anvil/Tools/ScanCore.pm b/Anvil/Tools/ScanCore.pm
index da503dd4..7e6cf3bf 100644
--- a/Anvil/Tools/ScanCore.pm
+++ b/Anvil/Tools/ScanCore.pm
@@ -2022,13 +2022,25 @@ sub post_scan_analysis_node
 			# Last, evaluate health if we're otherwise OK
 			if ($peer_health > $local_health)
 			{
+				# The user may have set a migration threashold. 
+				my $difference = $peer_health - $local_health;
+				$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => $debug, list => { difference => $difference }});
+				
+				if (not $anvil->data->{feature}{scancore}{threshold}{'preventative-live-migration'})
+				{
+					$anvil->data->{feature}{scancore}{threshold}{'preventative-live-migration'} = 2;
+					$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => $debug, list => { 
+						'feature::scancore::threshold::preventative-live-migration' => $anvil->data->{feature}{scancore}{threshold}{'preventative-live-migration'},
+					}});
+				}
+				
 				# A user may disable health-based preventative live migrations. 
 				if ($anvil->data->{feature}{scancore}{disable}{'preventative-live-migration'})
 				{
 					# Do nothing.
 					$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, level => 0, key => "message_0239"});
 				}
-				else
+				elsif ($difference >= $anvil->data->{feature}{scancore}{threshold}{'preventative-live-migration'})
 				{
 					# How long has this been the case?
 					my $age = $anvil->Alert->check_condition_age({
diff --git a/share/words.xml b/share/words.xml
index e934f2e0..2584c794 100644
--- a/share/words.xml
+++ b/share/words.xml
@@ -576,7 +576,13 @@ sys::privacy::strong						=	#!data!sys::privacy::strong!#
 # Normally, if one node in the Anvil! is healthier than the other, it will pull the servers from the peer
 # on to it. This is a process called "preventative live migration". If you would like to disable this 
 # feature, set this to '1'.
-feature::scancore::disable::preventative-live-migration		=	0
+#feature::scancore::disable::preventative-live-migration	=	0
+
+# If "preventative live migration" is enabled, this sets the threshold to trigger migration. The difference
+# in health score has to be equal to or greater than the number below. The health scores are usually set to
+# '1' per event, though scan agents are free to assign higher scores per event. The default threshold is 
+# '2'. To migrate on any health difference, set this to '1'. Use whole numbers only. 
+#feature::scancore::threshold::preventative-live-migration	=	2
 
 ### Database
 # Database connections;