Switch to kingpin for flag parsing

Newer versions of github.com/prometheus/exporter-toolkit require a more
complex type as the configuration given to `web.ListenAndServe`. The
upstream package only provides a kingpin implementation of the flag
code.

Author: hansmi

go.mod

@@ -14,6 +14,8 @@ require (
 )
 
 require (
+	github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 // indirect
+	github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.1.2 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
@@ -38,6 +40,7 @@ require (
 	golang.org/x/text v0.3.7 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
 	google.golang.org/protobuf v1.28.1 // indirect
+	gopkg.in/alecthomas/kingpin.v2 v2.2.6 // indirect
 	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect

go.sum

@@ -67,9 +67,11 @@ github.com/VividCortex/gohistogram v1.0.0/go.mod h1:Pf5mBqqDxYaXu3hDrrU+w6nw50o/
 github.com/afex/hystrix-go v0.0.0-20180502004556-fa1af6a1f4f5/go.mod h1:SkGFH1ia65gfNATL8TAiHDNxPzPdmEL5uirI2Uyuz6c=
 github.com/ajstarks/svgo v0.0.0-20180226025133-644b8db467af/go.mod h1:K08gAheRH3/J6wwsYMMT4xOr94bZjxIelGM0+d/wbFw=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
+github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 h1:JYp7IbQjafoB+tBA3gMyHYHrpOtNuDiK/uB5uXxq5wM=
 github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alecthomas/units v0.0.0-20190717042225-c3de453c63f4/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
+github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d h1:UQZhZ2O0vMHr2cI+DC1Mbh0TJxzA3RcLoMsFw+aXw7E=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
 github.com/armon/circbuf v0.0.0-20150827004946-bbbad097214e/go.mod h1:3U/XgcO3hCbHZ8TKRvWD2dDTCfh9M9ya+I9JpbB7O8o=
@@ -958,6 +960,7 @@ google.golang.org/protobuf v1.27.1/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQ
 google.golang.org/protobuf v1.28.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 google.golang.org/protobuf v1.28.1 h1:d0NfwRgPtno5B1Wa6L2DAG+KivqkdutMf1UhdNx175w=
 google.golang.org/protobuf v1.28.1/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6 h1:jMFz6MfLP0/4fUyZle81rXUoxOBFi19VUFKVDOQfozc=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

main.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"flag"
 	"fmt"
 	"log"
 	"net/http"
@@ -11,21 +10,22 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/version"
 	"github.com/prometheus/exporter-toolkit/web"
+	"gopkg.in/alecthomas/kingpin.v2"
 
 	kitlog "github.com/go-kit/kit/log"
 )
 
 const metricPrefix = "lvm_"
 
 func main() {
-	showVersion := flag.Bool("version", false, "Output version information and exit")
-	listenAddress := flag.String("web.listen-address", ":9845", "The address to listen on for HTTP requests")
-	configFile := flag.String("web.config", "", "Path to config yaml file that can enable TLS or authentication")
-	metricsPath := flag.String("web.telemetry-path", "/metrics", "Path under which to expose metrics")
-	disableExporterMetrics := flag.Bool("web.disable-exporter-metrics", false, "Exclude metrics about the exporter itself")
-	cmd := flag.String("command", "/usr/sbin/lvm", "Path to the LVM binary")
+	showVersion := kingpin.Flag("version", "Output version information and exit").Bool()
+	listenAddress := kingpin.Flag("web.listen-address", "The address to listen on for HTTP requests").Default(":9845").String()
+	configFile := kingpin.Flag("web.config", "Path to config yaml file that can enable TLS or authentication").String()
+	metricsPath := kingpin.Flag("web.telemetry-path", "Path under which to expose metrics").Default("/metrics").String()
+	disableExporterMetrics := kingpin.Flag("web.disable-exporter-metrics", "Exclude metrics about the exporter itself").Bool()
+	cmd := kingpin.Flag("command", "Path to the LVM binary").Default("/usr/sbin/lvm").String()
 
-	flag.Parse()
+	kingpin.Parse()
 
 	if *showVersion {
 		fmt.Println(version.Print("prometheus-lvm-exporter"))