app/vmauth: clarify the description for -idleConnTimeout command-line flag

This is a follow-up for d44058bcd6
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/6388

app/vmauth/main.go

@@ -37,8 +37,8 @@ var (
 		"With enabled proxy protocol http server cannot serve regular /metrics endpoint. Use -pushmetrics.url for metrics pushing")
 	maxIdleConnsPerBackend = flag.Int("maxIdleConnsPerBackend", 100, "The maximum number of idle connections vmauth can open per each backend host. "+
 		"See also -maxConcurrentRequests")
-	idleConnTimeout = flag.Duration("idleConnTimeout", 50*time.Second, `Defines a duration for idle (keep-alive connections) to exist.
-    Consider setting this value less than "-http.idleConnTimeout". It must prevent possible "write: broken pipe" and "read: connection reset by peer" errors.`)
+	idleConnTimeout = flag.Duration("idleConnTimeout", 50*time.Second, "The timeout for HTTP keep-alive connections to backend services. "+
+		"It is recommended setting this value to values smaller than -http.idleConnTimeout set at backend services")
 	responseTimeout       = flag.Duration("responseTimeout", 5*time.Minute, "The timeout for receiving a response from backend")
 	maxConcurrentRequests = flag.Int("maxConcurrentRequests", 1000, "The maximum number of concurrent requests vmauth can process. Other requests are rejected with "+
 		"'429 Too Many Requests' http status code. See also -maxConcurrentPerUserRequests and -maxIdleConnsPerBackend command-line options")
@@ -272,8 +272,7 @@ again:
 			ui.backendErrors.Inc()
 			return true
 		}
-		// one time retry trivial network errors, such as proxy idle timeout misconfiguration
-		// or socket close by OS
+		// one time retry trivial network errors, such as proxy idle timeout misconfiguration or socket close by OS
 		if (netutil.IsTrivialNetworkError(err) || errors.Is(err, io.EOF)) && trivialRetries < 1 {
 			trivialRetries++
 			goto again

docs/CHANGELOG.md

@@ -78,8 +78,8 @@ Released at 2024-06-24
 
 * FEATURE: [alerts-vmagent](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/deployment/docker/alerts-vmagent.yml): add new alerting rules `StreamAggrFlushTimeout` and `StreamAggrDedupFlushTimeout` to notify about issues during stream aggregation.
 * FEATURE: [dashboards/vmagent](https://grafana.com/grafana/dashboards/12683): add row `Streaming aggregation` with panels related to [streaming aggregation](https://docs.victoriametrics.com/stream-aggregation/) process.
-* FEATURE: [vmauth](https://docs.victoriametrics.com/vmauth/): add `idleConnTimeout` flag set to 50s by default. It should reduce the probability of `broken pipe` or `connection reset by peer` errors in vmauth logs.
-* FEATURE: [vmauth](https://docs.victoriametrics.com/vmauth/): add auto request retry for trivial network errors, such as `broken pipe` and `connection reset` for requests to the configured backends.
+* FEATURE: [vmauth](https://docs.victoriametrics.com/vmauth/): add `-idleConnTimeout` flag set to 50s by default. It should reduce the probability of `broken pipe` or `connection reset by peer` errors in vmauth logs.
+* FEATURE: [vmauth](https://docs.victoriametrics.com/vmauth/): add automatic retry for requests to backend for trivial network errors, such as `broken pipe` and `connection reset` for requests to the configured backends.
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent/): increase default value of `-promscrape.maxDroppedTargets` command-line flag to 10_000 from 1000. This makes it easier to track down large number of dropped targets. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6381).
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent/): add `max_scrape_size` parameter to a scrape config for setting a custom scrape limit for a job. The new [automatically generated metric](https://docs.victoriametrics.com/vmagent/#automatically-generated-metrics) `scrape_response_size_bytes` was added to reflect the response size of the target. See these issues: [1](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6429), [2](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2992), [3](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6123), [4](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5612).
 * FEATURE: [vmsingle](https://docs.victoriametrics.com/single-server-victoriametrics/): check for ranged vector arguments in non-rollup expressions when `-search.disableImplicitConversion` or `-search.logImplicitConversion` are enabled. For example, `sum(up[5m])` or `absent(up[5m])` will fail to execute if these flags are set.
@@ -127,7 +127,7 @@ Released at 2024-06-07
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent/): support Statsd plaintext protocol. See [these docs](https://docs.victoriametrics.com/vmagent/#how-to-push-data-to-vmagent) and this [pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5053). Thanks to @Koilanetroc for implementation!
 * FEATURE: [stream aggregation](https://docs.victoriametrics.com/stream-aggregation/): add [rate_sum](https://docs.victoriametrics.com/stream-aggregation/#rate_sum) and [rate_avg](https://docs.victoriametrics.com/stream-aggregation/#rate_avg) aggregation outputs.
 * FEATURE: [stream aggregation](https://docs.victoriametrics.com/stream-aggregation/): reduce the number of allocated objects in heap during deduplication and aggregation. The change supposed to reduce pressure on Garbage Collector, as it will need to scan less objects. See [this pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/6402).
-* FEATURE: [vmalert](https://docs.victoriametrics.com/vmalert/): add `datasource.idleConnTimeout`, `remoteWrite.idleConnTimeout` and `remoteRead.idleConnTimeout` flags. These flags are set to 50s by default and should reduce the probability of `broken pipe` or `connection reset by peer` errors in vmalert logs. See this [issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5661) for details.
+* FEATURE: [vmalert](https://docs.victoriametrics.com/vmalert/): add `-datasource.idleConnTimeout`, `-remoteWrite.idleConnTimeout` and `-remoteRead.idleConnTimeout` flags. These flags are set to 50s by default and should reduce the probability of `broken pipe` or `connection reset by peer` errors in vmalert logs. See this [issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5661) for details.
 * FEATURE: [vmalert](https://docs.victoriametrics.com/vmalert/): add auto request retry for trivial network errors, such as `broken pipe` and `connection reset` for requests to `remoteRead`, `remoteWrite` and `datasource` URLs. See this [issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5661) for details.
 * FEATURE: [vmalert](https://docs.victoriametrics.com/vmalert/): reduce CPU usage when evaluating high number of alerting and recording rules.
 * FEATURE: [vmalert](https://docs.victoriametrics.com/vmalert/): speed up retrieving rules files from object storages by skipping unchanged objects during reloading. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6210).

docs/vmauth.md

@@ -1218,7 +1218,7 @@ See the docs at https://docs.victoriametrics.com/vmauth/ .
      Supports array of values separated by comma or specified via multiple flags.
      Empty values are set to false.
   -idleConnTimeout duration
-    Defines a duration for idle (keep-alive connections) to exist. Consider setting this value less than "-http.idleConnTimeout". It must prevent possible "write: broken pipe" and "read: connection reset by peer" errors. (default 50s)
+    The timeout for HTTP keep-alive connections to backend services. It is recommended setting this value to values smaller than -http.idleConnTimeout set at backend services (default 50s)
   -internStringCacheExpireDuration duration
      The expiry duration for caches for interned strings. See https://en.wikipedia.org/wiki/String_interning . See also -internStringMaxLen and -internStringDisableCache (default 6m0s)
   -internStringDisableCache