improve docs for cli flags (#1202)

* improve docs for cli flags

* improve docs for cli flags.2

app/vmalert/datasource/init.go

@@ -11,24 +11,20 @@ import (
 var (
 	addr = flag.String("datasource.url", "", "Victoria Metrics or VMSelect url. Required parameter."+
 		" E.g. http://127.0.0.1:8428")
-	appendTypePrefix  = flag.Bool("datasource.appendTypePrefix", false, "Whether to add type prefix to -datasource.url based on the query type. Set to true if sending different query types to VMSelect URL.")
+	appendTypePrefix  = flag.Bool("datasource.appendTypePrefix", false, "Whether to add type prefix to -datasource.url based on the query type. Set to true if sending different query types to the VMSelect URL.")
 	basicAuthUsername = flag.String("datasource.basicAuth.username", "", "Optional basic auth username for -datasource.url")
 	basicAuthPassword = flag.String("datasource.basicAuth.password", "", "Optional basic auth password for -datasource.url")
 
 	tlsInsecureSkipVerify = flag.Bool("datasource.tlsInsecureSkipVerify", false, "Whether to skip tls verification when connecting to -datasource.url")
 	tlsCertFile           = flag.String("datasource.tlsCertFile", "", "Optional path to client-side TLS certificate file to use when connecting to -datasource.url")
 	tlsKeyFile            = flag.String("datasource.tlsKeyFile", "", "Optional path to client-side TLS certificate key to use when connecting to -datasource.url")
-	tlsCAFile             = flag.String("datasource.tlsCAFile", "", "Optional path to TLS CA file to use for verifying connections to -datasource.url. "+
-		"By default system CA is used")
-	tlsServerName = flag.String("datasource.tlsServerName", "", "Optional TLS server name to use for connections to -datasource.url. "+
-		"By default the server name from -datasource.url is used")
+	tlsCAFile             = flag.String("datasource.tlsCAFile", "", `Optional path to TLS CA file to use for verifying connections to -datasource.url. By default, system CA is used`)
+	tlsServerName         = flag.String("datasource.tlsServerName", "", `Optional TLS server name to use for connections to -datasource.url. By default, the server name from -datasource.url is used`)
 
-	lookBack = flag.Duration("datasource.lookback", 0, "Lookback defines how far to look into past when evaluating queries. "+
-		"For example, if datasource.lookback=5m then param \"time\" with value now()-5m will be added to every query.")
+	lookBack  = flag.Duration("datasource.lookback", 0, `Lookback defines how far into the past to look when evaluating queries. For example, if the datasource.lookback=5m then param "time" with value now()-5m will be added to every query.`)
 	queryStep = flag.Duration("datasource.queryStep", 0, "queryStep defines how far a value can fallback to when evaluating queries. "+
 		"For example, if datasource.queryStep=15s then param \"step\" with value \"15s\" will be added to every query.")
-	maxIdleConnections = flag.Int("datasource.maxIdleConnections", 100, "Defines the number of idle (keep-alive connections) to configured datasource."+
-		"Consider to set this value equal to the value: groups_total * group.concurrency. Too low value may result into high number of sockets in TIME_WAIT state.")
+	maxIdleConnections = flag.Int("datasource.maxIdleConnections", 100, `Defines the number of idle (keep-alive connections) to each configured datasource. Consider setting this value equal to the value: groups_total * group.concurrency. Too low a value may result in a high number of sockets in TIME_WAIT state.`)
 )
 
 // Init creates a Querier from provided flag values.

lib/flagutil/array.go

@@ -10,7 +10,7 @@ import (
 
 // NewArray returns new Array with the given name and description.
 func NewArray(name, description string) *Array {
-	description += "\nSupports `array` of values separated by comma" +
+	description += "\nSupports an `array` of values separated by comma" +
 		" or specified via multiple flags."
 	var a Array
 	flag.Var(&a, name, description)

lib/httpserver/httpserver.go

@@ -28,7 +28,7 @@ import (
 
 var (
 	tlsEnable   = flag.Bool("tls", false, "Whether to enable TLS (aka HTTPS) for incoming requests. -tlsCertFile and -tlsKeyFile must be set if -tls is set")
-	tlsCertFile = flag.String("tlsCertFile", "", "Path to file with TLS certificate. Used only if -tls is set. Prefer ECDSA certs instead of RSA certs, since RSA certs are slow")
+	tlsCertFile = flag.String("tlsCertFile", "", "Path to file with TLS certificate. Used only if -tls is set. Prefer ECDSA certs instead of RSA certs as RSA certs are slower")
 	tlsKeyFile  = flag.String("tlsKeyFile", "", "Path to file with TLS key. Used only if -tls is set")
 
 	pathPrefix = flag.String("http.pathPrefix", "", "An optional prefix to add to all the paths handled by http server. For example, if '-http.pathPrefix=/foo/bar' is set, "+
@@ -39,14 +39,11 @@ var (
 	metricsAuthKey   = flag.String("metricsAuthKey", "", "Auth key for /metrics. It overrides httpAuth settings")
 	pprofAuthKey     = flag.String("pprofAuthKey", "", "Auth key for /debug/pprof. It overrides httpAuth settings")
 
-	disableResponseCompression  = flag.Bool("http.disableResponseCompression", false, "Disable compression of HTTP responses for saving CPU resources. By default compression is enabled to save network bandwidth")
-	maxGracefulShutdownDuration = flag.Duration("http.maxGracefulShutdownDuration", 7*time.Second, "The maximum duration for graceful shutdown of HTTP server. "+
-		"Highly loaded server may require increased value for graceful shutdown")
-	shutdownDelay = flag.Duration("http.shutdownDelay", 0, "Optional delay before http server shutdown. During this dealy the servier 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", 2*time.Minute, "Incoming http connections are closed after the configured timeout. This may help spreading incoming load "+
-		"among a cluster of services behind load balancer. Note that the real timeout may be bigger by up to 10% as a protection from Thundering herd problem")
+	disableResponseCompression  = flag.Bool("http.disableResponseCompression", false, "Disable compression of HTTP responses to save CPU resources. By default compression is enabled to save network bandwidth")
+	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 dealay, the servier 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", 2*time.Minute, `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`)
 )
 
 var (

lib/logger/logger.go

@@ -24,10 +24,8 @@ var (
 		"For example: America/New_York, Europe/Berlin, Etc/GMT+3 or Local")
 	disableTimestamps = flag.Bool("loggerDisableTimestamps", false, "Whether to disable writing timestamps in logs")
 
-	errorsPerSecondLimit = flag.Int("loggerErrorsPerSecondLimit", 0, "Per-second limit on the number of ERROR messages. If more than the given number of errors "+
-		"are emitted per second, then the remaining errors are suppressed. Zero value disables the rate limit")
-	warnsPerSecondLimit = flag.Int("loggerWarnsPerSecondLimit", 0, "Per-second limit on the number of WARN messages. If more than the given number of warns "+
-		"are emitted per second, then the remaining warns are suppressed. Zero value disables the rate limit")
+	errorsPerSecondLimit = flag.Int("loggerErrorsPerSecondLimit", 0, `Per-second limit on the number of ERROR messages. If more than the given number of errors are emitted per second, the remaining errors are suppressed. Zero values disable the rate limit`)
+	warnsPerSecondLimit  = flag.Int("loggerWarnsPerSecondLimit", 0, `Per-second limit on the number of WARN messages. If more than the given number of warns are emitted per second, then the remaining warns are suppressed. Zero values disable the rate limit`)
 )
 
 // Init initializes the logger.

lib/memory/memory.go

@@ -10,14 +10,8 @@ import (
 )
 
 var (
-	allowedPercent = flag.Float64("memory.allowedPercent", 60, "Allowed percent of system memory VictoriaMetrics caches may occupy. "+
-		"See also -memory.allowedBytes. "+
-		"Too low value may increase cache miss rate, which usually results in higher CPU and disk IO usage. "+
-		"Too high value may evict too much data from OS page cache, which will result in higher disk IO usage")
-	allowedBytes = flagutil.NewBytes("memory.allowedBytes", 0, "Allowed size of system memory VictoriaMetrics caches may occupy. "+
-		"This option overrides -memory.allowedPercent if set to non-zero value. "+
-		"Too low value may increase cache miss rate, which usually results in higher CPU and disk IO usage. "+
-		"Too high value may evict too much data from OS page cache, which will result in higher disk IO usage")
+	allowedPercent = flag.Float64("memory.allowedPercent", 60, `Allowed percent of system memory VictoriaMetrics caches may occupy. See also -memory.allowedBytes. Too low a value may increase cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from OS page cache which will result in higher disk IO usage`)
+	allowedBytes   = flagutil.NewBytes("memory.allowedBytes", 0, `Allowed size of system memory VictoriaMetrics caches may occupy. This option overrides -memory.allowedPercent if set to a non-zero value. Too low a value may increase the cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from OS page cache resulting in higher disk IO usage`)
 )
 
 var (