lib/httpserver: return back the default value for -http.connTimeout to 2 minutes

It has been appeared that there are VictoriaMetrics users, who rely on the fact that
VictoriaMetrics components were closing incoming connections to -httpListenAddr every 2 minutes
by default. So let's return back this value by default in order to fix the breaking change
made at d8c1db7953 .

See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1304#issuecomment-1961891450 .

README.md

@@ -2684,7 +2684,7 @@ Pass `-help` to VictoriaMetrics in order to see the list of supported command-li
   -graphiteTrimTimestamp duration
      Trim timestamps for Graphite data to this duration. Minimum practical duration is 1s. Higher duration (i.e. 1m) may be used for reducing disk space usage for timestamp data (default 1s)
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'

docs/CHANGELOG.md

@@ -41,6 +41,7 @@ See also [LTS releases](https://docs.victoriametrics.com/LTS-releases.html).
 * FEATURE: [vmui](https://docs.victoriametrics.com/#vmui): preserve [`WITH` templates](https://play.victoriametrics.com/select/accounting/1/6a716b0f-38bc-4856-90ce-448fd713e3fe/expand-with-exprs) when clicking the `prettify query` button at the right side of query input field. See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5383).
 * FEATURE: [vmalert](https://docs.victoriametrics.com/#vmalert): support filtering by group, rule or labels in [vmalert's UI](https://docs.victoriametrics.com/vmalert/#web) for `/groups` and `/alerts` pages. See [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5791) by @victoramsantos.
 
+* BUGFIX: all VictoriaMetrics components: return back periodic closing of incoming connections to `-httpListenAddr` every 2 minutes, which was disabled in [v1.98.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.98.0) when addressing [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1304#issuecomment-1636997037). See [this comment](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1304#issuecomment-1961891450) for details on why the periodic closing of incoming connections has been returned back.
 * BUGFIX: [vmagent](https://docs.victoriametrics.com/vmagent.html): fix possible deadlock when [sharding among remote storages](https://docs.victoriametrics.com/vmagent/#sharding-among-remote-storages) is enabled with `-remoteWrite.shardByURL` command-line flag. Thanks to @penguinlav for [the fix](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5834) for [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5833).
 * BUGFIX: fix the misleading error `0ms is out of allowed range [0 ...` when passing `step=0` to [/api/v1/query](https://docs.victoriametrics.com/keyconcepts/#instant-query)
   or [/api/v1/query_range](https://docs.victoriametrics.com/keyconcepts/#range-query). See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5795).

docs/Cluster-VictoriaMetrics.md

@@ -1044,7 +1044,7 @@ Below is the output for `/path/to/vminsert -help`:
   -graphiteTrimTimestamp duration
      Trim timestamps for Graphite data to this duration. Minimum practical duration is 1s. Higher duration (i.e. 1m) may be used for reducing disk space usage for timestamp data (default 1s)
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'
@@ -1318,7 +1318,7 @@ Below is the output for `/path/to/vmselect -help`:
   -fs.disableMmap
      Whether to use pread() instead of mmap() for reading data files. By default, mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'
@@ -1622,7 +1622,7 @@ Below is the output for `/path/to/vmstorage -help`:
   -fs.disableMmap
      Whether to use pread() instead of mmap() for reading data files. By default, mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'

docs/VictoriaLogs/README.md

@@ -159,7 +159,7 @@ Pass `-help` to VictoriaLogs in order to see the list of supported command-line
   -gogc int
     	GOGC to use. See https://tip.golang.org/doc/gc-guide (default 100)
   -http.connTimeout duration
-    	Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem (default 2m0s)
+        Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
     	Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp string

docs/vmagent.md

@@ -1663,7 +1663,7 @@ See the docs at https://docs.victoriametrics.com/vmagent.html .
   -graphiteTrimTimestamp duration
      Trim timestamps for Graphite data to this duration. Minimum practical duration is 1s. Higher duration (i.e. 1m) may be used for reducing disk space usage for timestamp data (default 1s)
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'

docs/vmalert.md

@@ -1058,7 +1058,7 @@ The shortlist of configuration flags is the following:
   -fs.disableMmap
      Whether to use pread() instead of mmap() for reading data files. By default, mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'

docs/vmauth.md

@@ -887,7 +887,7 @@ See the docs at https://docs.victoriametrics.com/vmauth.html .
   -fs.disableMmap
      Whether to use pread() instead of mmap() for reading data files. By default, mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'

docs/vmbackup.md

@@ -338,7 +338,7 @@ Run `vmbackup -help` in order to see all the available options:
   -fs.disableMmap
      Whether to use pread() instead of mmap() for reading data files. By default, mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'

docs/vmbackupmanager.md

@@ -465,7 +465,7 @@ command-line flags:
   -fs.disableMmap
      Whether to use pread() instead of mmap() for reading data files. By default, mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem (default 2m0s)
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'

docs/vmgateway.md

@@ -368,7 +368,7 @@ Below is the list of configuration flags (it can be viewed by running `./vmgatew
   -fs.disableMmap
      Whether to use pread() instead of mmap() for reading data files. By default, mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'

docs/vmrestore.md

@@ -122,7 +122,7 @@ i.e. the end result would be similar to [rsync --delete](https://askubuntu.com/q
   -fs.disableMmap
      Whether to use pread() instead of mmap() for reading data files. By default, mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
   -http.connTimeout duration
-     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem
+     Incoming connections to -httpListenAddr are closed after the configured timeout. This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections (default 2m0s)
   -http.disableResponseCompression
      Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
   -http.header.csp default-src 'self'

lib/httpserver/httpserver.go

@@ -54,11 +54,12 @@ var (
 	maxGracefulShutdownDuration = flag.Duration("http.maxGracefulShutdownDuration", 7*time.Second, `The maximum duration for a graceful shutdown of the HTTP server. A highly loaded server may require increased value for a graceful shutdown`)
 	shutdownDelay               = flag.Duration("http.shutdownDelay", 0, `Optional delay before http server shutdown. During this delay, the server returns non-OK responses from /health page, so load balancers can route new requests to other servers`)
 	idleConnTimeout             = flag.Duration("http.idleConnTimeout", time.Minute, "Timeout for incoming idle http connections")
-	connTimeout                 = flag.Duration("http.connTimeout", 0, `Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem`)
+	connTimeout                 = flag.Duration("http.connTimeout", 2*time.Minute, "Incoming connections to -httpListenAddr are closed after the configured timeout. "+
+		"This may help evenly spreading load among a cluster of services behind TCP-level load balancer. Zero value disables closing of incoming connections")
 
-	headerHSTS         = flag.String("http.header.hsts", "", "Value for 'Strict-Transport-Security' header, recommended: `max-age=31536000; includeSubDomains`")
+	headerHSTS         = flag.String("http.header.hsts", "", "Value for 'Strict-Transport-Security' header, recommended: 'max-age=31536000; includeSubDomains'")
 	headerFrameOptions = flag.String("http.header.frameOptions", "", "Value for 'X-Frame-Options' header")
-	headerCSP          = flag.String("http.header.csp", "", "Value for 'Content-Security-Policy' header, recommended: `default-src 'self'`")
+	headerCSP          = flag.String("http.header.csp", "", `Value for 'Content-Security-Policy' header, recommended: "default-src 'self'"`)
 )
 
 var (