t3c: sort peers in strategies.yaml (#7182)

Author: traeak

CHANGELOG.md

@@ -51,6 +51,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - [#7137](https://github.com/apache/trafficcontrol/pull/7137) *Traffic Control Cache Config (t3c)* parent.config simulate topology for non topo delivery services.
 - [#7153](https://github.com/apache/trafficcontrol/pull/7153) *Traffic Control Cache Config (t3c)* Adds an extra T3C check for validity of an ssl cert (crash fix).
 - [#3965](https://github.com/apache/trafficcontrol/pull/3965) *Traffic Router* Traffic Router now always includes a `Content-Length` header in the response.
+- [#7182](https://github.com/apache/trafficcontrol/pull/7182) Sort peers used in strategy.yaml to prevent false positive for reload.
 
 ## [7.0.0] - 2022-07-19
 ### Added

lib/go-atscfg/parentabstraction.go

@@ -232,6 +232,12 @@ func (sp ParentAbstractionServiceParent) Key() string {
 	return sp.FQDN + ":" + strconv.Itoa(sp.Port)
 }
 
+type peersSort []*ParentAbstractionServiceParent
+
+func (a peersSort) Len() int           { return len(a) }
+func (a peersSort) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a peersSort) Less(i, j int) bool { return a[i].Key() < a[j].Key() }
+
 func RemoveParentDuplicates(inputs []*ParentAbstractionServiceParent, seens map[string]struct{}) ([]*ParentAbstractionServiceParent, map[string]struct{}) {
 	if seens == nil {
 		seens = make(map[string]struct{})

lib/go-atscfg/parentdotconfig.go

@@ -402,6 +402,8 @@ func makeParentDotConfigData(
 		parentAbstraction.Peers = append(parentAbstraction.Peers, peer)
 	}
 
+	sort.Sort(peersSort(parentAbstraction.Peers))
+
 	cgServerIDs := map[int]struct{}{}
 	for serverID, _ := range cgServers {
 		cgServerIDs[serverID] = struct{}{}