Add go_gomaxprocs, go_gogc_percent and go_gomemlimit to the default Go runtime metrics

Signed-off-by: Arianna Vespri <arianna.vespri@yahoo.it>

go.mod

@@ -18,6 +18,7 @@ require (
 
 require (
 	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/hashicorp/go-version v1.7.0
 	github.com/jpillora/backoff v1.0.0 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect

go.sum

@@ -14,6 +14,8 @@ github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
+github.com/hashicorp/go-version v1.7.0 h1:5tqGy27NaOTB8yJKUZELlFAS/LTKJkrmONwQKeRZfjY=
+github.com/hashicorp/go-version v1.7.0/go.mod h1:fltr4n8CU8Ke44wwGCBoEymUuxUHl09ZGVZPK5anwXA=
 github.com/jpillora/backoff v1.0.0 h1:uvFg412JmmHBHw7iwprIxkPMI+sGQ4kzOWsMeHnm2EA=
 github.com/jpillora/backoff v1.0.0/go.mod h1:J/6gKK9jxlEcS3zixgDgUAsiuZ7yrSoa/FX5e0EB2j4=
 github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=

prometheus/collectors/go_collector_latest_test.go

@@ -31,6 +31,9 @@ import (
 
 var baseMetrics = []string{
 	"go_gc_duration_seconds",
+	"go_gogc_percent",
+	"go_gomaxprocs",
+	"go_gomemlimit",
 	"go_goroutines",
 	"go_info",
 	"go_memstats_last_gc_time_seconds",

prometheus/go_collector.go

@@ -16,6 +16,7 @@ package prometheus
 import (
 	"runtime"
 	"runtime/debug"
+	runmetr "runtime/metrics"
 	"time"
 )
 
@@ -211,6 +212,9 @@ type baseGoCollector struct {
 	gcDesc         *Desc
 	gcLastTimeDesc *Desc
 	goInfoDesc     *Desc
+	goMaxProcs     *Desc
+	goGogcPercent  *Desc
+	goMemLimit     *Desc
 }
 
 func newBaseGoCollector() baseGoCollector {
@@ -235,6 +239,18 @@ func newBaseGoCollector() baseGoCollector {
 			"go_info",
 			"Information about the Go environment.",
 			nil, Labels{"version": runtime.Version()}),
+		goMaxProcs: NewDesc(
+			"go_gomaxprocs",
+			"Value of GOMAXPROCS, i.e number of usable threads.",
+			nil, nil),
+		goGogcPercent: NewDesc(
+			"go_gogc_percent",
+			"Value of GOGC (percentage).",
+			nil, nil),
+		goMemLimit: NewDesc(
+			"go_gomemlimit",
+			"Value of GOMEMLIMIT (bytes).",
+			nil, nil),
 	}
 }
 
@@ -245,6 +261,9 @@ func (c *baseGoCollector) Describe(ch chan<- *Desc) {
 	ch <- c.gcDesc
 	ch <- c.gcLastTimeDesc
 	ch <- c.goInfoDesc
+	ch <- c.goMaxProcs
+	ch <- c.goGogcPercent
+	ch <- c.goMemLimit
 }
 
 // Collect returns the current state of all metrics of the collector.
@@ -266,6 +285,18 @@ func (c *baseGoCollector) Collect(ch chan<- Metric) {
 	ch <- MustNewConstSummary(c.gcDesc, uint64(stats.NumGC), stats.PauseTotal.Seconds(), quantiles)
 	ch <- MustNewConstMetric(c.gcLastTimeDesc, GaugeValue, float64(stats.LastGC.UnixNano())/1e9)
 	ch <- MustNewConstMetric(c.goInfoDesc, GaugeValue, 1)
+	ch <- MustNewConstMetric(c.goMaxProcs, GaugeValue, float64(runtime.NumCPU()))
+
+	gogcSample := make([]runmetr.Sample, 1)
+	gogcSample[0].Name = "/gc/gogc:percent"
+	runmetr.Read(gogcSample)
+	ch <- MustNewConstMetric(c.goGogcPercent, GaugeValue, float64(gogcSample[0].Value.Uint64()))
+
+	memLimitSample := make([]runmetr.Sample, 1)
+	memLimitSample[0].Name = "/gc/gomemlimit:bytes"
+	runmetr.Read(memLimitSample)
+	ch <- MustNewConstMetric(c.goMemLimit, GaugeValue, float64(memLimitSample[0].Value.Uint64()))
+
 }
 
 func memstatNamespace(s string) string {

prometheus/go_collector_latest_test.go

@@ -54,6 +54,9 @@ func expectedBaseMetrics() map[string]struct{} {
 		b.goroutinesDesc.fqName,
 		b.gcLastTimeDesc.fqName,
 		b.threadsDesc.fqName,
+		b.goMaxProcs.fqName,
+		b.goGogcPercent.fqName,
+		b.goMemLimit.fqName,
 	} {
 		metrics[m] = struct{}{}
 	}