scripts: Allow to export metrics in markdorn

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

scripts/export-metrics/main.go

@@ -1,10 +1,13 @@
 package main
 
 import (
+	"bytes"
 	"encoding/json"
 	"flag"
 	"fmt"
 	"os"
+	"sort"
+	"strings"
 
 	local_metrics "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/metrics"
 	"git.frostfs.info/TrueCloudLab/frostfs-observability/metrics"
@@ -13,6 +16,7 @@ import (
 var (
 	node   = flag.String("node", "", "File to export storage node metrics to.")
 	ir     = flag.String("ir", "", "File to export innerring node metrics to.")
+	format = flag.String("format", "json", "Format to export in. Supported formats: json (default), md.")
 )
 
 func main() {
@@ -37,13 +41,35 @@ func main() {
 		os.Exit(1)
 	}
 
-	ds := metrics.DescribeAll()
+	var data []byte
+	var err error
 
-	data, err := json.Marshal(ds)
+	ds := metrics.DescribeAll()
+	switch *format {
+	case "md":
+		sort.Slice(ds, func(i, j int) bool {
+			return ds[i].Name < ds[j].Name
+		})
+		b := bytes.NewBuffer(nil)
+		b.WriteString("# FrostFS Node prometheus metrics\n")
+		b.WriteString("Name | Description | Constant labels | Variable labels\n")
+		b.WriteString("-- | -- | -- | --\n")
+		for i := range ds {
+			constLabels := make([]string, 0, len(ds[i].ConstantLabels))
+			for key, value := range ds[i].ConstantLabels {
+				constLabels = append(constLabels, fmt.Sprintf("%s=%s", key, value))
+			}
+			varLabels := strings.Join(ds[i].VariableLabels, "; ")
+			fmt.Fprintf(b, "%s | %s | %s | %s\n", ds[i].Name, ds[i].Help, strings.Join(constLabels, "; "), varLabels)
+		}
+		data = b.Bytes()
+	default:
+		data, err = json.Marshal(ds)
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Could not parse marshal: %v\n", err)
 			os.Exit(1)
 		}
+	}
 
 	if err := os.WriteFile(filename, data, 0o644); err != nil {
 		fmt.Fprintf(os.Stderr, "Could write to file: %v\n", err)