feat(pyroscope/scrape): set scrape_interval as upper limit for `pro…

…filing_duration`

Signed-off-by: hainenber <[email protected]>

docs/sources/reference/components/pyroscope.scrape.md

@@ -398,8 +398,9 @@ When the `delta` argument is `true`:
 * A `seconds` parameter is automatically added to the HTTP request.
 * The default value for the `seconds` query parameter is `scrape_interval - 1`.
     If you set `profiling_duration`, then `seconds` is assigned the same value as `profiling_duration`.
-    For example, if you set `scrape_interval` to `"15s"`, then `seconds` defaults to `14s`.
-    If you set `profiling_duration` to `16s`, then `seconds` is set to `16s` regardless of the `scrape_interval` value.
+    However, the `profiling_duration` cannot be larger than `scrape_interval`. 
+    For example, if you set `scrape_interval` to `"15s"`, then `seconds` defaults to `14s`
+    If you set `profiling_duration` to `16s`, then `scrape_interval` must be set to at least `17s`.
   If the HTTP endpoint is `/debug/pprof/profile`, then the HTTP query will become `/debug/pprof/profile?seconds=14`
 
 ## Exported fields

internal/component/pyroscope/scrape/scrape.go

@@ -31,7 +31,7 @@ const (
 	pprofGoDeltaProfBlock    string        = "godeltaprof_block"
 	pprofGoDeltaProfMutex    string        = "godeltaprof_mutex"
 	defaultScrapeInterval    time.Duration = 15 * time.Second
-	defaultProfilingDuration time.Duration = defaultScrapeInterval - 1 * time.Second
+	defaultProfilingDuration time.Duration = defaultScrapeInterval - 1*time.Second
 )
 
 func init() {
@@ -223,8 +223,13 @@ func (arg *Arguments) Validate() error {
 		if target.Enabled && target.Delta && arg.ScrapeInterval.Seconds() < 2 {
 			return fmt.Errorf("scrape_interval must be at least 2 seconds when using delta profiling")
 		}
-		if target.Enabled && target.Delta && arg.ProfilingDuration.Seconds() <= 1 {
-			return fmt.Errorf("profiling_duration must be larger then 1 second when using delta profiling")
+		if target.Enabled && target.Delta {
+			if arg.ProfilingDuration.Seconds() <= 1 {
+				return fmt.Errorf("profiling_duration must be larger than 1 second when using delta profiling")
+			}
+			if arg.ProfilingDuration.Seconds() >= arg.ScrapeInterval.Seconds() {
+				return fmt.Errorf("profiling_duration must be smaller than scrape_interval when using delta profiling")
+			}
 		}
 	}
 

internal/component/pyroscope/scrape/scrape_test.go

@@ -161,6 +161,16 @@ func TestUnmarshalConfig(t *testing.T) {
 			`,
 			expectedErr: "profiling_duration must be larger then 1 second when using delta profiling",
 		},
+		"erroneous cpu profiling_duration": {
+			in: `
+			targets    = []
+			forward_to = null
+			scrape_timeout = "1s"
+			scrape_interval = "10s"
+			profiling_duration = "12s"
+			`,
+			expectedErr: "profiling_duration must be smaller than scrape_interval when using delta profiling",
+		},
 		"allow short scrape_intervals without delta": {
 			in: `
 			targets    = []