update docs and flag details to indicate DNS lookup is used for ring …

…lookup.

docs/sources/configuration/_index.md

@@ -315,8 +315,9 @@ The query_frontend_config configures the Loki query-frontend.
 
 # How often to resolve the scheduler-address, in order to look for new
 # query-scheduler instances.
+# Also used to determine how often to poll the scheduler-ring for addresses if configured.
 # CLI flag: -frontend.scheduler-dns-lookup-period
-[scheduler_dns_lookup_period: <duration> | default = 10s]
+[scheduler_dns_lookup_period: <duration> | default = 3s]
 
 # Number of concurrent workers forwarding queries to single query-scheduler.
 # CLI flag: -frontend.scheduler-worker-concurrency
@@ -776,9 +777,10 @@ The `frontend_worker_config` configures the worker - running within the Loki que
 # CLI flag: -querier.worker-parallelism
 [parallelism: <int> | default = 10]
 
-# How often to query DNS.
+# How often to query the frontend_address DNS to resolve frontend addresses
+# Also used to determine how often to poll the scheduler-ring for addresses if configured.
 # CLI flag: -querier.dns-lookup-period
-[dns_lookup_duration: <duration> | default = 10s]
+[dns_lookup_duration: <duration> | default = 3s]
 
 # The CLI flags prefix for this block config is: querier.frontend-client
 [grpc_client_config: <grpc_client_config>]

pkg/lokifrontend/frontend/v2/frontend.go

@@ -44,7 +44,7 @@ type Config struct {
 
 func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
 	f.StringVar(&cfg.SchedulerAddress, "frontend.scheduler-address", "", "DNS hostname used for finding query-schedulers.")
-	f.DurationVar(&cfg.DNSLookupPeriod, "frontend.scheduler-dns-lookup-period", 10*time.Second, "How often to resolve the scheduler-address, in order to look for new query-scheduler instances.")
+	f.DurationVar(&cfg.DNSLookupPeriod, "frontend.scheduler-dns-lookup-period", 10*time.Second, "How often to resolve the scheduler-address, in order to look for new query-scheduler instances.  Also used to determine how often to poll the scheduler-ring for addresses if the scheduler-ring is configured.")
 	f.IntVar(&cfg.WorkerConcurrency, "frontend.scheduler-worker-concurrency", 5, "Number of concurrent workers forwarding queries to single query-scheduler.")
 
 	cfg.InfNames = []string{"eth0", "en0"}

pkg/querier/worker/worker.go

@@ -39,7 +39,7 @@ func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
 	f.StringVar(&cfg.SchedulerAddress, "querier.scheduler-address", "", "Hostname (and port) of scheduler that querier will periodically resolve, connect to and receive queries from. Only one of -querier.frontend-address or -querier.scheduler-address can be set. If neither is set, queries are only received via HTTP endpoint.")
 	f.StringVar(&cfg.FrontendAddress, "querier.frontend-address", "", "Address of query frontend service, in host:port format. If -querier.scheduler-address is set as well, querier will use scheduler instead. Only one of -querier.frontend-address or -querier.scheduler-address can be set. If neither is set, queries are only received via HTTP endpoint.")
 
-	f.DurationVar(&cfg.DNSLookupPeriod, "querier.dns-lookup-period", 3*time.Second, "How often to query DNS for query-frontend or query-scheduler address.")
+	f.DurationVar(&cfg.DNSLookupPeriod, "querier.dns-lookup-period", 3*time.Second, "How often to query DNS for query-frontend or query-scheduler address. Also used to determine how often to poll the scheduler-ring for addresses if the scheduler-ring is configured.")
 
 	f.IntVar(&cfg.Parallelism, "querier.worker-parallelism", 10, "Number of simultaneous queries to process per query-frontend or query-scheduler.")
 	f.BoolVar(&cfg.MatchMaxConcurrency, "querier.worker-match-max-concurrent", false, "Force worker concurrency to match the -querier.max-concurrent option. Overrides querier.worker-parallelism.")