From 09ee53a23063a6be670afb2018868762bd36c865 Mon Sep 17 00:00:00 2001
From: Emmanuel Lodovice <lodovice@amazon.com>
Date: Tue, 14 Nov 2023 10:03:37 -0800
Subject: [PATCH] Skip listing rule groups in CreateRuleGroup api if max rule
 groups limit is not set (#5653)

Signed-off-by: Emmanuel Lodovice <lodovice@amazon.com>
---
 pkg/ruler/api.go   | 22 ++++++++++++----------
 pkg/ruler/ruler.go |  6 ++++++
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/pkg/ruler/api.go b/pkg/ruler/api.go
index 48debd328a..e76bc0830b 100644
--- a/pkg/ruler/api.go
+++ b/pkg/ruler/api.go
@@ -527,17 +527,19 @@ func (a *API) CreateRuleGroup(w http.ResponseWriter, req *http.Request) {
 		return
 	}
 
-	rgs, err := a.store.ListRuleGroupsForUserAndNamespace(req.Context(), userID, "")
-	if err != nil {
-		level.Error(logger).Log("msg", "unable to fetch current rule groups for validation", "err", err.Error(), "user", userID)
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
+	if a.ruler.HasMaxRuleGroupsLimit(userID) {
+		rgs, err := a.store.ListRuleGroupsForUserAndNamespace(req.Context(), userID, "")
+		if err != nil {
+			level.Error(logger).Log("msg", "unable to fetch current rule groups for validation", "err", err.Error(), "user", userID)
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
 
-	if err := a.ruler.AssertMaxRuleGroups(userID, len(rgs)+1); err != nil {
-		level.Error(logger).Log("msg", "limit validation failure", "err", err.Error(), "user", userID)
-		http.Error(w, err.Error(), http.StatusBadRequest)
-		return
+		if err := a.ruler.AssertMaxRuleGroups(userID, len(rgs)+1); err != nil {
+			level.Error(logger).Log("msg", "limit validation failure", "err", err.Error(), "user", userID)
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
 	}
 
 	rgProto := rulespb.ToProto(userID, namespace, rg)
diff --git a/pkg/ruler/ruler.go b/pkg/ruler/ruler.go
index 3cb56cb326..29799acc45 100644
--- a/pkg/ruler/ruler.go
+++ b/pkg/ruler/ruler.go
@@ -939,6 +939,12 @@ func (r *Ruler) Rules(ctx context.Context, in *RulesRequest) (*RulesResponse, er
 	return &RulesResponse{Groups: groupDescs}, nil
 }
 
+// HasMaxRuleGroupsLimit check if RulerMaxRuleGroupsPerTenant limit is set for the userID.
+func (r *Ruler) HasMaxRuleGroupsLimit(userID string) bool {
+	limit := r.limits.RulerMaxRuleGroupsPerTenant(userID)
+	return limit > 0
+}
+
 // AssertMaxRuleGroups limit has not been reached compared to the current
 // number of total rule groups in input and returns an error if so.
 func (r *Ruler) AssertMaxRuleGroups(userID string, rg int) error {