add flag to report internal metrics on resource usage

cmd/config.go

@@ -22,18 +22,20 @@ Options:
 -t --timeout   <int>          When should the operation timeout in seconds
 -s --sleeptime <int>          Time to sleep between checks (default: 5s)
 -l --label     <label=value>  Add label to exported metric
+-i --internals                Also add labels about resource usage
 -h --help                     Show help
 -v --version                  Show program version`
 )
 
 // config via commandline flags
 type Config struct {
-	Showversion bool     `koanf:"version"` // -v
-	Showhelp    bool     `koanf:"help"`    // -h
-	Label       []string `koanf:"label"`   // -v
-	Timeout     int      `koanf:"timeout"` // -t
-	Port        int      `koanf:"port"`    // -p
-	Sleeptime   int      `koanf:"sleep"`   // -s
+	Showversion bool     `koanf:"version"`   // -v
+	Showhelp    bool     `koanf:"help"`      // -h
+	Internals   bool     `koanf:"internals"` // -i
+	Label       []string `koanf:"label"`     // -v
+	Timeout     int      `koanf:"timeout"`   // -t
+	Port        int      `koanf:"port"`      // -p
+	Sleeptime   int      `koanf:"sleep"`     // -s
 
 	File   string
 	Labels []Label
@@ -54,6 +56,7 @@ func InitConfig(output io.Writer) (*Config, error) {
 	// parse commandline flags
 	flagset.BoolP("version", "v", false, "show program version")
 	flagset.BoolP("help", "h", false, "show help")
+	flagset.BoolP("internals", "i", false, "add internal metrics")
 	flagset.StringArrayP("label", "l", nil, "additional labels")
 	flagset.IntP("timeout", "t", 1, "timeout for file operation in seconds")
 	flagset.IntP("port", "p", 9187, "prometheus metrics port to listen to")

cmd/metrics.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
 )
 
 // custom labels
@@ -49,7 +50,23 @@ func NewMetrics(conf *Config) *Metrics {
 		registry: prometheus.NewRegistry(),
 	}
 
-	metrics.registry.MustRegister(metrics.run, metrics.latency)
+	if conf.Internals {
+		metrics.registry.MustRegister(
+			metrics.run,
+			metrics.latency,
+
+			// we  might need  to take  care of the  exporter in  terms of
+			// resources, so also report those internals
+			collectors.NewGoCollector(
+				collectors.WithGoCollectorMemStatsMetricsDisabled(),
+			),
+			collectors.NewProcessCollector(
+				collectors.ProcessCollectorOpts{},
+			),
+		)
+	} else {
+		metrics.registry.MustRegister(metrics.run, metrics.latency)
+	}
 
 	// static labels
 	metrics.values[0] = conf.File