Add a flag to disable step alignment middleware

CHANGELOG.md

@@ -20,6 +20,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 - [#3346](https://github.com/thanos-io/thanos/pull/3346) Ruler UI: Fix a bug preventing the /rules endpoint from loading.
 - [#3115](https://github.com/thanos-io/thanos/pull/3115) compact: now deletes partially uploaded and blocks with deletion marks concurrently. It does that at the beginning and then every `--compact.cleanup-interval` time period. By default it is 5 minutes.
 - [#3312](https://github.com/thanos-io/thanos/pull/3312) s3: add list_objects_version config option for compatibility.
+- [#3356](https://github.com/thanos-io/thanos/pull/3356) Query Frontend: Add a flag to disable step alignment middleware for query range.
 
 ### Fixed
 - [#3257](https://github.com/thanos-io/thanos/pull/3257) Ruler: Prevent Ruler from crashing when using default DNS to lookup hosts that results in "No such hosts" errors.

cmd/thanos/query_frontend.go

@@ -57,6 +57,9 @@ func registerQueryFrontend(app *extkingpin.App) {
 	cfg.http.registerFlag(cmd)
 
 	// Query range tripperware flags.
+	cmd.Flag("query-range.align-range-with-step", "Mutate incoming queries to align their start and end with their step for better cache-ability. Note: Grafana dashboards do that by default.").
+		Default("true").BoolVar(&cfg.QueryRangeConfig.AlignRangeWithStep)
+
 	cmd.Flag("query-range.split-interval", "Split query range requests by an interval and execute in parallel, it should be greater than 0 when query-range.response-cache-config is configured.").
 		Default("24h").DurationVar(&cfg.QueryRangeConfig.SplitQueriesByInterval)
 

docs/components/query-frontend.md

@@ -126,6 +126,11 @@ Flags:
                                  Listen host:port for HTTP endpoints.
       --http-grace-period=2m     Time to wait after an interrupt received for
                                  HTTP Server.
+      --query-range.align-range-with-step
+                                 Mutate incoming queries to align their start
+                                 and end with their step for better
+                                 cache-ability. Note: Grafana dashboards do that
+                                 by default.
       --query-range.split-interval=24h
                                  Split query range requests by an interval and
                                  execute in parallel, it should be greater than

pkg/queryfrontend/config.go

@@ -139,6 +139,7 @@ type QueryRangeConfig struct {
 	ResultsCacheConfig *queryrange.ResultsCacheConfig
 	CachePathOrContent extflag.PathOrContent
 
+	AlignRangeWithStep     bool
 	SplitQueriesByInterval time.Duration
 	MaxRetries             int
 	Limits                 *cortexvalidation.Limits

pkg/queryfrontend/roundtrip.go

@@ -144,11 +144,13 @@ func newQueryRangeTripperware(
 	m := queryrange.NewInstrumentMiddlewareMetrics(reg)
 
 	// step align middleware.
-	queryRangeMiddleware = append(
-		queryRangeMiddleware,
-		queryrange.InstrumentMiddleware("step_align", m),
-		queryrange.StepAlignMiddleware,
-	)
+	if config.AlignRangeWithStep {
+		queryRangeMiddleware = append(
+			queryRangeMiddleware,
+			queryrange.InstrumentMiddleware("step_align", m),
+			queryrange.StepAlignMiddleware,
+		)
+	}
 
 	queryIntervalFn := func(_ queryrange.Request) time.Duration {
 		return config.SplitQueriesByInterval