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better-mid-cluster-mgm.xml
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<?xml version="1.0" encoding="UTF-8"?><unload unload_date="2020-06-30 11:11:56">
<sys_remote_update_set action="INSERT_OR_UPDATE">
<application display_value="Global">global</application>
<application_name>Global</application_name>
<application_scope>global</application_scope>
<application_version/>
<collisions/>
<commit_date/>
<deleted/>
<description/>
<inserted/>
<name>Better MID Cluster Management</name>
<origin_sys_id/>
<parent display_value=""/>
<release_date/>
<remote_base_update_set display_value=""/>
<remote_parent_id/>
<remote_sys_id>6afaf15c073d1010409ff4218c1ed0a8</remote_sys_id>
<state>loaded</state>
<summary/>
<sys_class_name>sys_remote_update_set</sys_class_name>
<sys_created_by>admin</sys_created_by>
<sys_created_on>2020-06-30 11:11:56</sys_created_on>
<sys_id>a7530a58077d1010409ff4218c1ed0fb</sys_id>
<sys_mod_count>0</sys_mod_count>
<sys_updated_by>admin</sys_updated_by>
<sys_updated_on>2020-06-30 11:11:56</sys_updated_on>
<update_set display_value=""/>
<update_source display_value=""/>
<updated/>
</sys_remote_update_set>
<sys_update_xml action="INSERT_OR_UPDATE">
<action>INSERT_OR_UPDATE</action>
<application display_value="Global">global</application>
<category>customer</category>
<comments/>
<name>sys_script_cbfcf5dc073d1010409ff4218c1ed039</name>
<payload><?xml version="1.0" encoding="UTF-8"?><record_update sys_domain="global" table="sys_script"><sys_script action="INSERT_OR_UPDATE"><abort_action>false</abort_action><access>package_private</access><action_delete>false</action_delete><action_insert>true</action_insert><action_query>false</action_query><action_update>false</action_update><active>true</active><add_message>false</add_message><advanced>true</advanced><change_fields>false</change_fields><client_callable>false</client_callable><collection>ecc_queue</collection><condition>current.agent.startsWith("mid.server.") &amp;&amp; current.queue == "output" &amp;&amp; current.topic != 'HeartbeatProbe' &amp;&amp; !current.topic.startsWith('queue.') &amp;&amp; !current.topic.startsWith('MIDExtension:')</condition><description/><execute_function>false</execute_function><filter_condition/><is_rest>false</is_rest><message/><name>Better MID Server Cluster Management</name><order>80</order><priority>100</priority><rest_method/><rest_method_text/><rest_service/><rest_service_text/><rest_variables/><role_conditions/><script><![CDATA[/**
* Better MID Cluster Management
*
* This is a drop in replacement for the 'MID Server Cluster Management' business rule (/sys_script.do?sys_id=297749870a0006bc2145d31c2d2335b9)
* Make sure /sys_script.do?sys_id=297749870a0006bc2145d31c2d2335b9 is active=false!
*
* Unfortunately the OOB LB/FO script is not very mature and assigns always the same FO agent in case of agent down.
*
* For more details see https://github.com/bmoers/sn-better-mid-cluster-mgmt/blob/master/README.md
*
* The source and test cases can be found here https://github.com/bmoers/sn-better-mid-cluster-mgmt
*
*/
(function (current) {
/**
* Find a Load Balancer for the passed Agent.
* Lookup logic:
* - get all load balancer agents of the current agent
* - find failover agents for stopped load balancer agents
* - get a random agent from all agents collected above
*
* (This function runs only 2 SQL queries in total)
*
* @param {GlideRecord} agentGr The GlideRecord of the agent to load balance or failover
* @returns {String} The agent name (The LB or if no LB found the current one)
*/
var findLoadBalancerForAgent = function (agentGr) {
if (!agentGr)
return;
var agentSysId = agentGr.getValue('sys_id');
var agentFallbackName = "mid.server." + agentGr.getValue('name');
var UP_STATE = 'Up';
var FAILOVER = 'Failover';
var DEBUG_ENABLED = gs.getProperty('better_mid_server.cluster.debug', 'false') == 'true';
var log = {
debug: function () {
if (!DEBUG_ENABLED)
return;
var args = Array.prototype.slice.call(arguments);
if (args.length)
args[0] = '[Better MID Cluster] : ' + args[0];
gs.debug.apply(this, args);
},
info: function () {
var args = Array.prototype.slice.call(arguments);
if (args.length)
args[0] = '[Better MID Cluster] : ' + args[0];
gs.info.apply(this, args);
}
};
/**
* Helper function to make fields in an array unique.
* @param {*} value
* @param {*} index
* @param {*} self
*/
var onlyUnique = function (value, index, self) {
return self.indexOf(value) === index;
};
/**
* Find all capabilities for the passed agents in ONE sql query.
*
* @param {Array} agentSysIds
* @returns {Object} object with capabilities per key
*/
var _getAgentCapabilities = function (agentSysIds) {
if (!agentSysIds)
return null;
var agentCaps = {};
var agentSysIdArr = Array.isArray(agentSysIds) ? agentSysIds : [agentSysIds];
var gr = new GlideRecord("ecc_agent_capability_m2m");
gr.addQuery("agent", 'IN', agentSysIdArr.join(','));
gr.query();
log.debug("_getAgentCapabilities : ecc_agent_capability_m2m.do " + gr.getEncodedQuery());
while (gr.next()) {
var sysId = gr.getValue('agent');
if (!agentCaps[sysId])
agentCaps[sysId] = [];
if (JSUtil.nil(gr.capability.value)) {
agentCaps[sysId].push(gr.capability.capability.toString());
} else {
agentCaps[sysId].push(gr.capability.capability.toString() + ':' + gr.capability.value.toString());
}
}
return agentCaps;
};
/**
* Check if Array2 is in Array1
* @param {*} array1
* @param {*} array2
* @returns {Boolean}
*/
var _isSubset = function (array1, array2) {
var resArray = new ArrayUtil().intersect(array1, array2);
if (resArray.length == array1.length)
return true;
return false;
};
/**
* Find all cluster agents which have the same or more capabilities
* In contrast to the OOB ServiceNow function, this also treats 'ALL' as
* capable to take over all other capabilities.
*
* @param {String} agentSysId
* @param {Array} failoverAgents
* @returns {Array} list holding the sys_id of the capable agents
*/
var _filterOnCapabilities = function (agentSysId, failoverAgents) {
var agentCaps = _getAgentCapabilities(agentSysId)[agentSysId];
var newClusterAgents = [];
if (!agentCaps)
return newClusterAgents;
var foCapabilities = _getAgentCapabilities(failoverAgents);
if (!foCapabilities)
return newClusterAgents;
Object.keys(foCapabilities).forEach(function (foAgentSysId) {
var candidateCaps = foCapabilities[foAgentSysId];
log.debug("_filterOnCapabilities : Agent caps " + JSON.stringify(agentCaps) + " - candidateCaps :" + JSON.stringify(candidateCaps));
// if the candidate can do 'ALL' it is always capable to take over
if (candidateCaps.indexOf('ALL') !== -1) {
newClusterAgents.push(foAgentSysId);
} else if (_isSubset(agentCaps, candidateCaps)) { // check the candidate capabilities are more or equal the current
newClusterAgents.push(foAgentSysId);
}
});
return newClusterAgents;
};
/**
* Get the clusterMember construct.
* @returns {Object} of following structure : {
agents: {
SYS_ID: {
failover: [],
loadBalance: [],
up: true,
name : name
}
},
failover: {
SYS_ID : {
agentsUp: []
}
},
loadBalance: {
SYS_ID: {
agentsUp : []
agentsDown : []
}
}
};
*/
var getAllClusterMembers = function () {
// get all clusters
var gr = new GlideRecord('ecc_agent_cluster_member_m2m');
gr.query();
var allClusters = {
agents: {},
failover: {},
loadBalance: {}
};
// build up 'allClusters' object
while (gr.next()) {
var clusterSysId = gr.cluster.toString();
var clusterType = gr.cluster.type.toString(); // 'Load Balance' / 'Failover'
var type = (clusterType == FAILOVER) ? 'failover' : 'loadBalance';
var isFailover = (clusterType == FAILOVER);
var agentSysId = gr.agent.toString();
var agentName = gr.agent.name.toString();
var agentStatus = gr.agent.status.toString(); // 'Up' / 'Down' / 'Upgrade Failed'
var isUp = (agentStatus == UP_STATE);
// all agents
if (!allClusters.agents[agentSysId])
allClusters.agents[agentSysId] = { failover: [], loadBalance: [], up: isUp, name: agentName };
allClusters.agents[agentSysId][type].push(clusterSysId);
// for the clusters we need all agents, regardless if up or down
if (!allClusters[type][clusterSysId]) {
allClusters[type][clusterSysId] = { agentsUp: [] };
if (!isFailover) {
// only load balancer have agentsDown
allClusters[type][clusterSysId].agentsDown = [];
}
}
/*
add all LoadBalance clusters agents
add all running failover clusters agents
*/
if (!isFailover) {
if (isUp) {
allClusters[type][clusterSysId].agentsUp.push(agentSysId);
} else {
allClusters[type][clusterSysId].agentsDown.push(agentSysId);
}
} else if (isFailover && isUp) {
// only keep the running failover agents
allClusters[type][clusterSysId].agentsUp.push(agentSysId);
}
}
log.debug('getAllClusterMembers : ' + JSON.stringify(allClusters));
return allClusters;
};
var getRandomMidServer = function (sameCapFoAgents) {
log.debug("getRandomMidServer : up and running agents with same capabilities " + JSON.stringify(sameCapFoAgents));
var lbAgentsNum = sameCapFoAgents.length;
if (lbAgentsNum) {
var lbRandomPos = Math.floor(Math.random() * lbAgentsNum);
var lbRandomSysId = sameCapFoAgents[lbRandomPos];
var agentCache = new SNC.ECCAgentCache();
var gr = agentCache.getBySysId(lbRandomSysId);
if (gr) {
return "mid.server." + gr.getValue('name');
}
}
return null;
};
var getSameCapAgentFromFailover = function (currAgent) {
var upFailoverAgents = [];
currAgent.failover.forEach(function (foSysId) {
// find all the down load balancers nodes and replace it with one failover node
var fo = allClusters.failover[foSysId];
if (!fo)
return;
upFailoverAgents = upFailoverAgents.concat(fo.agentsUp);
});
var sameCapFoAgents = _filterOnCapabilities(agentSysId, upFailoverAgents);
return getRandomMidServer(sameCapFoAgents);
};
var getSameCapAgentFromLoadBalance = function (currAgent) {
// list of agents to share the load
var upLoadBalanceAgents = [];
var downLoadBalanceAgents = [];
var upFailoverAgents = [];
// these are all load balancers to the current mid server
currAgent.loadBalance.forEach(function (lbSysId) {
// find all the down load balancers nodes and replace it with one failover node
var loadBalancer = allClusters.loadBalance[lbSysId];
if (!loadBalancer)
return;
upLoadBalanceAgents = upLoadBalanceAgents.concat(loadBalancer.agentsUp);
downLoadBalanceAgents = downLoadBalanceAgents.concat(loadBalancer.agentsDown);
});
// remove duplicates
upLoadBalanceAgents = upLoadBalanceAgents.filter(onlyUnique);
downLoadBalanceAgents = downLoadBalanceAgents.filter(onlyUnique);
log.debug("getSameCapAgentFromLoadBalance : current agent load balancers " + JSON.stringify(currAgent.loadBalance));
log.debug("getSameCapAgentFromLoadBalance : current agent running load balancer partners " + JSON.stringify(upLoadBalanceAgents));
log.debug("getSameCapAgentFromLoadBalance : current agent stopped load balancer partners " + JSON.stringify(downLoadBalanceAgents));
downLoadBalanceAgents.forEach(function (downAgentSysId) {
var downAgent = allClusters.agents[downAgentSysId];
// check if there is a failover in place for this agent
if (!downAgent || downAgent.failover.length == 0)
return;
downAgent.failover.forEach(function (failoverSysId) {
var failoverCluster = allClusters.failover[failoverSysId];
// check if the failover cluster has active agents
if (!failoverCluster || failoverCluster.agentsUp.length == 0)
return;
upFailoverAgents = upFailoverAgents.concat(failoverCluster.agentsUp);
});
});
// remove duplicates
upFailoverAgents = upFailoverAgents.filter(onlyUnique);
log.debug("getSameCapAgentFromLoadBalance : up running failover agents " + JSON.stringify(upFailoverAgents) + " to take over from stopped " + JSON.stringify(downLoadBalanceAgents));
log.debug("getSameCapAgentFromLoadBalance : num down agents " + downLoadBalanceAgents.length);
log.debug("getSameCapAgentFromLoadBalance : num failover agents " + upFailoverAgents.length);
// if there are less or equal number of failover agents in place, take them all
if (upFailoverAgents.length <= downLoadBalanceAgents.length) {
// we need all of them
upLoadBalanceAgents = upLoadBalanceAgents.concat(upFailoverAgents);
} else {
// there are more failover agents available then we need to have, random pick some
downLoadBalanceAgents.forEach(function () {
randomPos = Math.floor(Math.random() * upFailoverAgents.length);
// select a random failover from the remaining list
// splice makes the 'currentDownAgentsUpFailoverAgents' shorter by 1 every time it runs
upLoadBalanceAgents.push(upFailoverAgents.splice(randomPos, 1)[0]);
});
}
log.debug("getSameCapAgentFromLoadBalance : up and running agents " + JSON.stringify(upLoadBalanceAgents));
var sameCapFoAgents = _filterOnCapabilities(agentSysId, upLoadBalanceAgents);
return getRandomMidServer(sameCapFoAgents);
};
// get all defined clusters and members on the platform
var allClusters = getAllClusterMembers();
// get the current agent object from that cluster
var currAgent = allClusters.agents[agentSysId];
// check if the agent hast at least one failover or loadBalance agent
if (!currAgent || (currAgent.failover.length == 0 && currAgent.loadBalance.length == 0)) {
// mid server has no failover or load balance configuration
log.debug("no lb/fo agents found for agent (sys_id) " + agentSysId);
return agentFallbackName;
}
// there are no LB but Failover agents
if (currAgent.loadBalance.length == 0 && currAgent.failover.length != 0) {
// get one random failover with same capability
var foAgent = getSameCapAgentFromFailover(currAgent);
return foAgent || agentFallbackName;
}
var lbAgent = getSameCapAgentFromLoadBalance(currAgent);
return lbAgent || agentFallbackName;
};
/*
this is OOB code from /sys_script.do?sys_id=297749870a0006bc2145d31c2d2335b9 (MID Server Cluster Management)
START
*/
var getMIDServerGr = function () {
var agentName = current.agent;
agentName = agentName.substring("mid.server.".length, agentName.length);
var agentCache = new SNC.ECCAgentCache();
var gr = agentCache.getByName(agentName);
if (!gr)
return;
return gr;
};
if (current.topic == 'SystemCommand' || current.topic == "Command")
return;
if (current.topic == 'config.file')
return;
var agentGr = getMIDServerGr();
if (JSUtil.nil(agentGr))
return;
// only use cluster for Shazzam if the MID is down
if (current.topic == "Shazzam" && agentGr.status == "Up")
return;
// If probe param ECC_AGENT_SELECTOR_DETAILS exists in payload, then exit and don't use
// legacy cluster management. For performance, uses a cached regex instead of a real XML parser.
var midSelectorRegex = new SNC.Regex(GlideappIECC.ECC_AGENT_SELECTOR_DETAILS_REGEX + '');
if (midSelectorRegex.match(current.payload))
return;
/*
END
*/
/*
find a load balancer
*/
current.agent = findLoadBalancerForAgent(agentGr);
})(current);]]></script><sys_class_name>sys_script</sys_class_name><sys_created_by>admin</sys_created_by><sys_created_on>2020-06-30 10:44:03</sys_created_on><sys_domain>global</sys_domain><sys_domain_path>/</sys_domain_path><sys_id>cbfcf5dc073d1010409ff4218c1ed039</sys_id><sys_mod_count>6</sys_mod_count><sys_name>Better MID Server Cluster Management</sys_name><sys_overrides/><sys_package display_value="Global" source="global">global</sys_package><sys_policy/><sys_scope display_value="Global">global</sys_scope><sys_update_name>sys_script_cbfcf5dc073d1010409ff4218c1ed039</sys_update_name><sys_updated_by>admin</sys_updated_by><sys_updated_on>2020-06-30 11:07:20</sys_updated_on><template/><when>before</when></sys_script><sys_translated_text action="delete_multiple" query="documentkey=cbfcf5dc073d1010409ff4218c1ed039"/></record_update></payload>
<payload_hash>358362553</payload_hash>
<remote_update_set display_value="Better MID Cluster Management">a7530a58077d1010409ff4218c1ed0fb</remote_update_set>
<replace_on_upgrade>false</replace_on_upgrade>
<sys_created_by>admin</sys_created_by>
<sys_created_on>2020-06-30 11:11:56</sys_created_on>
<sys_id>eb530a58077d1010409ff4218c1ed0fb</sys_id>
<sys_mod_count>0</sys_mod_count>
<sys_recorded_at>17304e8eca90000001</sys_recorded_at>
<sys_updated_by>admin</sys_updated_by>
<sys_updated_on>2020-06-30 11:11:56</sys_updated_on>
<table>ecc_queue</table>
<target_name>Better MID Server Cluster Management</target_name>
<type>Business Rule</type>
<update_domain>global</update_domain>
<update_guid>50520a188c7d1010d7191e483ac93561</update_guid>
<update_guid_history>50520a188c7d1010d7191e483ac93561:358362553,2311ce948a7d10103d2de9c70606d42b:525165546,45d04254647d1010b180edd4a61bb2b3:464763920,65b08a14fd7d1010b36104113726b975:1132570028,7bbdf150d87d10101bca5e49b59fc764:358362553,eabd7510c07d101025ed5dc4c7ced352:-1212429238,8ffcf5dcff3d1010d7a1fa3d03ee753c:-1815060396</update_guid_history>
<update_set display_value=""/>
<view/>
</sys_update_xml>
</unload>