Add a 'reserved ENIs' metric

ipamd/ipamd.go

@@ -133,6 +133,12 @@ var (
 			Help: "The maximum number of ENIs that can be attached to the instance",
 		},
 	)
+	reservedENIs = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "awscni_eni_reserved",
+			Help: "The number of ENIs that are reserved on this instance",
+		},
+	)
 	ipMax = prometheus.NewGauge(
 		prometheus.GaugeOpts{
 			Name: "awscni_ip_max",
@@ -282,15 +288,13 @@ func (c *IPAMContext) nodeInit() error {
 		log.Error("Failed to get ENI limit")
 		return err
 	}
-	c.maxENI = nodeMaxENI - numReserved
-	enisMax.Set(float64(c.maxENI))
-
+	c.maxENI = nodeMaxENI
 	c.maxIPsPerENI, err = c.awsClient.GetENIipLimit()
 	if err != nil {
 		log.Error("Failed to get IPs per ENI limit")
 		return err
 	}
-	ipMax.Set(float64(c.maxIPsPerENI * c.maxENI))
+	c.updateIPStats(numReserved)
 
 	_, vpcCIDR, err := net.ParseCIDR(c.awsClient.GetVPCIPv4CIDR())
 	if err != nil {
@@ -390,6 +394,11 @@ func (c *IPAMContext) nodeInit() error {
 	return err
 }
 
+func (c *IPAMContext) updateIPStats(reserved int) {
+	ipMax.Set(float64(c.maxIPsPerENI * (c.maxENI - reserved)))
+	reservedENIs.Set(float64(reserved))
+}
+
 func (c *IPAMContext) getLocalPodsWithRetry() ([]*k8sapi.K8SPodInfo, error) {
 	var pods []*k8sapi.K8SPodInfo
 	var err error
@@ -917,7 +926,8 @@ func (c *IPAMContext) nodeIPPoolReconcile(interval time.Duration) {
 		ipamdErrInc("reconcileFailedGetENIs")
 		return
 	}
-	attachedENIs, _ := filterUnmanagedENIs(allENIs)
+	attachedENIs, numReserved := filterUnmanagedENIs(allENIs)
+	c.updateIPStats(numReserved)
 
 	curENIs := c.dataStore.GetENIInfos()