lib/{osinfo,appmetrics}: Move vm_os_info metric code to lib/appmetrics package (#10776)

Follow-up commit for
211fb08028

Address @f41gh7 review comments:
- Move code from `lib/osinfo` to `lib/appmetrics`.
- Make the logic private.
- Use metrics.WriteGaugeUint64 func.
- Remove registration logic from `app/xxx/main.go`.
- Remove `lib/osinfo` package.

app/victoria-metrics/main.go

@@ -19,7 +19,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/osinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/pushmetrics"
@@ -65,8 +64,6 @@ func main() {
 	buildinfo.Init()
 	logger.Init()
 
-	osinfo.ExposeAsMetric()
-
 	if promscrape.IsDryRun() {
 		*dryRun = true
 	}

app/vmagent/main.go

@@ -41,7 +41,6 @@ import (
 	opentsdbserver "github.com/VictoriaMetrics/VictoriaMetrics/lib/ingestserver/opentsdb"
 	opentsdbhttpserver "github.com/VictoriaMetrics/VictoriaMetrics/lib/ingestserver/opentsdbhttp"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/osinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/opentelemetry/firehose"
@@ -117,7 +116,6 @@ func main() {
 	buildinfo.Init()
 	logger.Init()
 	timeserieslimits.Init(*maxLabelsPerTimeseries, *maxLabelNameLen, *maxLabelValueLen)
-	osinfo.ExposeAsMetric()
 
 	if promscrape.IsDryRun() {
 		if err := promscrape.CheckConfig(); err != nil {

app/vmalert/main.go

@@ -26,7 +26,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/osinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/pushmetrics"
 )
@@ -95,7 +94,6 @@ func main() {
 	notifier.InitSecretFlags()
 	buildinfo.Init()
 	logger.Init()
-	osinfo.ExposeAsMetric()
 
 	var err error
 	extURL, err = getExternalURL(*externalURL)

app/vmauth/main.go

@@ -28,7 +28,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/ioutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/netutil"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/osinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promauth"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/pushmetrics"
@@ -100,7 +99,6 @@ func main() {
 	envflag.Parse()
 	buildinfo.Init()
 	logger.Init()
-	osinfo.ExposeAsMetric()
 
 	if *dryRun {
 		if len(*authConfigPath) == 0 {

app/vmbackup/main.go

@@ -19,7 +19,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/osinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/pushmetrics"
 
@@ -53,7 +52,6 @@ func main() {
 	envflag.Parse()
 	buildinfo.Init()
 	logger.Init()
-	osinfo.ExposeAsMetric()
 
 	ctx, cancel := context.WithCancel(context.Background())
 	go func() {

app/vminsert/main.go

@@ -37,7 +37,6 @@ import (
 	influxserver "github.com/VictoriaMetrics/VictoriaMetrics/lib/ingestserver/influx"
 	opentsdbserver "github.com/VictoriaMetrics/VictoriaMetrics/lib/ingestserver/opentsdb"
 	opentsdbhttpserver "github.com/VictoriaMetrics/VictoriaMetrics/lib/ingestserver/opentsdbhttp"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/osinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompb"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape"
@@ -107,7 +106,6 @@ func Init() {
 		prompush.Push(wr)
 	})
 	timeserieslimits.Init(*maxLabelsPerTimeseries, *maxLabelNameLen, *maxLabelValueLen)
-	osinfo.ExposeAsMetric()
 }
 
 // Stop stops vminsert.

app/vmrestore/main.go

@@ -15,7 +15,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/osinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/pushmetrics"
 )
@@ -41,7 +40,6 @@ func main() {
 	envflag.Parse()
 	buildinfo.Init()
 	logger.Init()
-	osinfo.ExposeAsMetric()
 
 	listenAddrs := []string{*httpListenAddr}
 	go httpserver.Serve(listenAddrs, nil, httpserver.ServeOptions{})

app/vmselect/main.go

@@ -27,7 +27,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httputil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/osinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/querytracer"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/timerpool"
@@ -70,7 +69,6 @@ func Init() {
 	concurrencyLimitCh = make(chan struct{}, *maxConcurrentRequests)
 	initVMUIConfig()
 	initVMAlertProxy()
-	osinfo.ExposeAsMetric()
 }
 
 // Stop stops vmselect

app/vmstorage/main.go

@@ -21,7 +21,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/mergeset"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/osinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/querytracer"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/storage"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/storage/metricnamestats"
@@ -173,7 +172,6 @@ func Init(resetCacheIfNeeded func(mrs []storage.MetricRow)) {
 		writeStorageMetrics(w, strg)
 	})
 	metrics.RegisterSet(storageMetrics)
-	osinfo.ExposeAsMetric()
 }
 
 var storageMetrics *metrics.Set

lib/appmetrics/appmetrics.go

@@ -36,6 +36,7 @@ func WritePrometheusMetrics(w io.Writer) {
 	if currentTime.Sub(metricsCacheLastUpdateTime) > time.Second {
 		var bb bytesutil.ByteBuffer
 		writePrometheusMetrics(&bb)
+		writeOSMetrics(&bb)
 		metricsCache.Store(&bb)
 		metricsCacheLastUpdateTime = currentTime
 	}

lib/appmetrics/osmetrics.go

@@ -0,0 +1,25 @@
+package appmetrics
+
+import (
+	"fmt"
+	"io"
+	"sync"
+
+	"github.com/VictoriaMetrics/metrics"
+)
+
+type osInfo struct {
+	name    string
+	release string
+}
+
+var os osInfo
+var initOSOnce sync.Once
+
+func writeOSMetrics(w io.Writer) {
+	initOSOnce.Do(initOS)
+
+	if os.name != "" {
+		metrics.WriteGaugeUint64(w, fmt.Sprintf(`vm_os_info{os=%q, release=%q}`, os.name, os.release), 1)
+	}
+}

lib/appmetrics/osmetrics_darwin.go

@@ -0,0 +1,20 @@
+package appmetrics
+
+import (
+	"os/exec"
+	"strings"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+)
+
+func initOS() {
+	os = osInfo{name: "darwin"}
+
+	out, err := exec.Command("sysctl", "-n", "kern.osrelease").Output()
+	if err != nil {
+		logger.Warnf("vm_os_info metric will miss release info since exec 'sysctl -n \"kern.osrelease\"' call failed: %s", err)
+		return
+	}
+
+	os.release = strings.TrimSpace(string(out))
+}

lib/appmetrics/osmetrics_linux.go

@@ -0,0 +1,26 @@
+package appmetrics
+
+import (
+	"syscall"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+)
+
+func initOS() {
+	os = osInfo{name: "linux"}
+
+	var uname syscall.Utsname
+	if err := syscall.Uname(&uname); err != nil {
+		logger.Warnf("vm_os_info metric will miss release info since syscall.Uname failed: %s", err)
+		return
+	}
+
+	ur := make([]byte, 0, len(uname.Release))
+	for _, v := range uname.Release {
+		if v == 0 {
+			break
+		}
+		ur = append(ur, byte(v))
+	}
+	os.release = string(ur)
+}

lib/appmetrics/osmetrics_other.go

@@ -1,5 +1,6 @@
 //go:build !linux && !windows && !darwin
 
-package osinfo
+package appmetrics
 
-func ExposeAsMetric() {}
+func initOS() {
+}

lib/appmetrics/osmetrics_windows.go

@@ -0,0 +1,19 @@
+package appmetrics
+
+import (
+	"fmt"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"golang.org/x/sys/windows"
+)
+
+func initOS() {
+	os = osInfo{name: "windows"}
+
+	ver := windows.RtlGetVersion()
+	if ver == nil {
+		logger.Warnf("vm_os_info metric will miss release info since windows.RtlGetVersion returned nil version")
+		return
+	}
+	os.release = fmt.Sprintf("%d.%d.%d", ver.MajorVersion, ver.MinorVersion, ver.BuildNumber)
+}

lib/osinfo/info_darwin.go

@@ -1,24 +0,0 @@
-package osinfo
-
-import (
-	"fmt"
-	"os/exec"
-	"strings"
-
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"github.com/VictoriaMetrics/metrics"
-)
-
-var darwinRelease string
-
-func ExposeAsMetric() {
-	out, err := exec.Command("sysctl", "-n", "kern.osrelease").Output()
-	if err != nil {
-		logger.Warnf("os info wont be exposed as vm_os_info metric; exec 'sysctl -n \"kern.osrelease\"' failed: %s", err)
-		return
-	}
-
-	darwinRelease = strings.TrimSpace(string(out))
-
-	_ = metrics.GetOrCreateGauge(fmt.Sprintf(`vm_os_info{os="darwin", release=%q}`, darwinRelease), func() float64 { return 1 })
-}

lib/osinfo/info_linux.go

@@ -1,30 +0,0 @@
-package osinfo
-
-import (
-	"fmt"
-	"syscall"
-
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"github.com/VictoriaMetrics/metrics"
-)
-
-var linuxRelease string
-
-func ExposeAsMetric() {
-	var uname syscall.Utsname
-	if err := syscall.Uname(&uname); err != nil {
-		logger.Warnf("os info wont be exposed as vm_os_info metric; failed to call syscall.Uname: %s", err)
-		return
-	}
-
-	release := make([]byte, 0, len(uname.Release))
-	for _, v := range uname.Release {
-		if v == 0 {
-			break
-		}
-		release = append(release, byte(v))
-	}
-	linuxRelease = string(release)
-
-	_ = metrics.GetOrCreateGauge(fmt.Sprintf(`vm_os_info{os="linux", release=%q}`, linuxRelease), func() float64 { return 1 })
-}

lib/osinfo/info_windows.go

@@ -1,21 +0,0 @@
-package osinfo
-
-import (
-	"fmt"
-
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"github.com/VictoriaMetrics/metrics"
-	"golang.org/x/sys/windows"
-)
-
-var windowsRelease string
-
-func ExposeAsMetric() {
-	ver := windows.RtlGetVersion()
-	if ver == nil {
-		logger.Warnf("os info wont be exposed as vm_os_info metric; windows.RtlGetVersion returned nil version")
-		return
-	}
-	windowsRelease = fmt.Sprintf("%d.%d.%d", ver.MajorVersion, ver.MinorVersion, ver.BuildNumber)
-	_ = metrics.GetOrCreateGauge(fmt.Sprintf(`vm_os_info{os="windows", release=%q}`, windowsRelease), func() float64 { return 1 })
-}