rule-sanitizer: avoid sorting rules

This change improves the rule-sanitizer library to avoid sorting all the
rules. This was originally done to simplify indexing rules with the same
names, but it turns out that integrating this lib can be complex to
review when all the rules of the manifests are reordered. Thus, it is
easier to just leave the file as it was initially sorted.

Signed-off-by: Damien Grisonnet <dgrisonn@redhat.com>

Author: dgrisonnet

jsonnet/kube-prometheus/lib/rule-sanitizer.libsonnet

@@ -83,32 +83,23 @@ local sameRuleName(rule1, rule2) =
   else
     false;
 
-local indexRules(lastRule, ruleSet) =
-  if std.length(ruleSet) == 0 then
+local indexRules(ruleSet, index) =
+  if std.length(ruleSet) == index then
     []
-  else if (lastRule != null) && sameRuleName(lastRule, ruleSet[0]) then
-    local updatedRule = std.mergePatch(ruleSet[0], { index: lastRule.index + 1 });
-    [updatedRule] + indexRules(updatedRule, ruleSet[1:])
-  else
-    local updatedRule = std.mergePatch(ruleSet[0], { index: 0 });
-    [updatedRule] + indexRules(updatedRule, ruleSet[1:]);
-
-local ruleName(rule) =
-  if ('alert' in rule) then
-    rule.alert
-  else if ('record' in rule) then
-    rule.record
   else
-    assert false : 'rule should have either "alert" or "record" field' + std.toString(rule);
-    '';
+    // First we find the number of occurences of the rule in the ruleSet and
+    // get an array containing the indexes of all the occurences.
+    // Then, based on the current index of the rule in the ruleSet we are able
+    // to deduce the index of the rule in the list of rules with the same name.
+    local ruleIndex = std.find(index, std.find(ruleSet[index], ruleSet))[0];
+    local updatedRule = std.mergePatch(ruleSet[index], { index: ruleIndex });
+    [updatedRule] + indexRules(ruleSet, index + 1);
 
 local patchOrExcludeRuleGroup(group, groupSet, operation) =
   if std.length(groupSet) == 0 then
     [group.rules]
   else if (group.name == groupSet[0].name) then
-    local indexedRules = indexRules(null, std.sort(
-      group.rules, keyF=ruleName
-    ));
+    local indexedRules = indexRules(group.rules, 0);
     [patchOrExcludeRule(rule, groupSet[0].rules, operation) for rule in indexedRules]
   else
     [] + patchOrExcludeRuleGroup(group, groupSet[1:], operation);