Add flag to disable guest CPU metrics

In high scale virtualized / cloud environments there are typically
no guest VMs. Add a boolean flag to allow disabling the Linux guest
CPU metrics.

Signed-off-by: Ben Kochie <superq@gmail.com>

CHANGELOG.md

@@ -5,6 +5,8 @@
 * [ENHANCEMENT]
 * [BUGFIX]
 
+* [ENHANCEMENT] Add flag to disable guest CPU metrics #2123
+
 ## 1.2.2 / 2021-08-06
 
 * [BUGFIX] Fix processes collector long int parsing #2112

collector/cpu_linux.go

@@ -50,6 +50,7 @@ type cpuCollector struct {
 const jumpBackSeconds = 3.0
 
 var (
+	enableCPUGuest       = kingpin.Flag("collector.cpu.guest", "Enables metric node_cpu_guest_seconds_total").Default("true").Bool()
 	enableCPUInfo        = kingpin.Flag("collector.cpu.info", "Enables metric cpu_info").Bool()
 	flagsInclude         = kingpin.Flag("collector.cpu.info.flags-include", "Filter the `flags` field in cpuInfo with a value that must be a regular expression").String()
 	bugsInclude          = kingpin.Flag("collector.cpu.info.bugs-include", "Filter the `bugs` field in cpuInfo with a value that must be a regular expression").String()
@@ -296,9 +297,11 @@ func (c *cpuCollector) updateStat(ch chan<- prometheus.Metric) error {
 		ch <- prometheus.MustNewConstMetric(c.cpu, prometheus.CounterValue, cpuStat.SoftIRQ, cpuNum, "softirq")
 		ch <- prometheus.MustNewConstMetric(c.cpu, prometheus.CounterValue, cpuStat.Steal, cpuNum, "steal")
 
-		// Guest CPU is also accounted for in cpuStat.User and cpuStat.Nice, expose these as separate metrics.
-		ch <- prometheus.MustNewConstMetric(c.cpuGuest, prometheus.CounterValue, cpuStat.Guest, cpuNum, "user")
-		ch <- prometheus.MustNewConstMetric(c.cpuGuest, prometheus.CounterValue, cpuStat.GuestNice, cpuNum, "nice")
+		if *enableCPUGuest {
+			// Guest CPU is also accounted for in cpuStat.User and cpuStat.Nice, expose these as separate metrics.
+			ch <- prometheus.MustNewConstMetric(c.cpuGuest, prometheus.CounterValue, cpuStat.Guest, cpuNum, "user")
+			ch <- prometheus.MustNewConstMetric(c.cpuGuest, prometheus.CounterValue, cpuStat.GuestNice, cpuNum, "nice")
+		}
 	}
 
 	return nil