pyroscope.scrape: Adjust handling of scrape_timeout

This automatically adapts the timeout when a ProfilingTarget is fetched
with Delta=true. In those cases the HTTP calll is block for
ScrapeInterval - 1s while the target profiles itself.

This also updates the ScrapeTimeout to 10s (default in prometheus).

component/pyroscope/scrape/scrape.go

@@ -193,7 +193,7 @@ func NewDefaultArguments() Arguments {
 		Scheme:           "http",
 		HTTPClientConfig: component_config.DefaultHTTPClientConfig,
 		ScrapeInterval:   15 * time.Second,
-		ScrapeTimeout:    15*time.Second + (3 * time.Second),
+		ScrapeTimeout:    10 * time.Second,
 		ProfilingConfig:  DefaultProfilingConfig,
 	}
 }
@@ -208,14 +208,12 @@ func (arg *Arguments) Validate() error {
 	if arg.ScrapeTimeout <= 0 {
 		return fmt.Errorf("scrape_timeout must be greater than 0")
 	}
-	if arg.ScrapeTimeout <= arg.ScrapeInterval {
-		return fmt.Errorf("scrape_timeout must be greater than scrape_interval")
-	}
 
-	if cfg, ok := arg.ProfilingConfig.ProcessCPU, true; ok {
-		if cfg.Enabled && arg.ScrapeTimeout < time.Second*2 {
-			return fmt.Errorf("%v scrape_timeout must be at least 2 seconds", pprofProcessCPU)
-		}
+	// ScrapeInterval must be at least 2 seconds, because if
+	// ProfilingTarget.Delta is true the ScrapeInterval - 1s is propagated in
+	// the `seconds` parameter and it must be >= 1.
+	if arg.ScrapeInterval <= 2 {
+		return fmt.Errorf("scrape_interval must be at least 2 seconds")
 	}
 
 	// We must explicitly Validate because HTTPClientConfig is squashed and it won't run otherwise

component/pyroscope/scrape/scrape_loop.go

@@ -174,6 +174,14 @@ type scrapeLoop struct {
 }
 
 func newScrapeLoop(t *Target, scrapeClient *http.Client, appendable pyroscope.Appendable, interval, timeout time.Duration, logger log.Logger) *scrapeLoop {
+
+	// if the URL parameter have a seconds parameter, then the collection will
+	// take at least scrape_duration - 1 second, as the HTTP request will block
+	// until the profile is collected.
+	if t.Params().Has("seconds") {
+		timeout += interval - time.Second
+	}
+
 	return &scrapeLoop{
 		Target:       t,
 		logger:       logger,