Update Ruler frontend_address comments to mention Store Gateway

docs/configuration/config-file-reference.md

@@ -5145,9 +5145,10 @@ The `redis_config` configures the Redis backend cache.
 The `ruler_config` configures the Cortex ruler.
 
 ```yaml
-# [Experimental] GRPC listen address of the Query Frontend, in host:port format.
-# If set, Ruler queries to Query Frontends via gRPC. If not set, ruler queries
-# to Ingesters directly.
+# [Experimental] gRPC address of the Query Frontend (host:port). If set, the
+# Ruler send queries to the Query Frontend to utilize splitting and caching, at
+# the cost of additional network hops compared to direct querying to Ingesters
+# and Store Gateway.
 # CLI flag: -ruler.frontend-address
 [frontend_address: <string> | default = ""]
 

pkg/ruler/ruler.go

@@ -231,7 +231,7 @@ func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
 	//lint:ignore faillint Need to pass the global logger like this for warning on deprecated methods
 	flagext.DeprecatedFlag(f, "ruler.alertmanager-use-v2", "This flag is no longer functional. V1 API is deprecated and removed", util_log.Logger)
 
-	f.StringVar(&cfg.FrontendAddress, "ruler.frontend-address", "", "[Experimental] GRPC listen address of the Query Frontend, in host:port format. If set, Ruler queries to Query Frontends via gRPC. If not set, ruler queries to Ingesters directly.")
+	f.StringVar(&cfg.FrontendAddress, "ruler.frontend-address", "", "[Experimental] gRPC address of the Query Frontend (host:port). If set, the Ruler send queries to the Query Frontend to utilize splitting and caching, at the cost of additional network hops compared to direct querying to Ingesters and Store Gateway.")
 	f.StringVar(&cfg.QueryResponseFormat, "ruler.query-response-format", queryResponseFormatProtobuf, fmt.Sprintf("[Experimental] Query response format to get query results from Query Frontend when the rule evaluation. It will only take effect when `-ruler.frontend-address` is configured. Supported values: %s", strings.Join(supportedQueryResponseFormats, ",")))
 	cfg.ExternalURL.URL, _ = url.Parse("") // Must be non-nil
 	f.Var(&cfg.ExternalURL, "ruler.external.url", "URL of alerts return path.")

schemas/cortex-config-schema.json

@@ -6587,7 +6587,7 @@
           "x-format": "duration"
         },
         "frontend_address": {
-          "description": "[Experimental] GRPC listen address of the Query Frontend, in host:port format. If set, Ruler queries to Query Frontends via gRPC. If not set, ruler queries to Ingesters directly.",
+          "description": "[Experimental] gRPC address of the Query Frontend (host:port). If set, the Ruler send queries to the Query Frontend to utilize splitting and caching, at the cost of additional network hops compared to direct querying to Ingesters and Store Gateway.",
           "type": "string",
           "x-cli-flag": "ruler.frontend-address"
         },