Add ReadyReplicas metric to deployment metric family

* Add ReadyReplicas field in Deployment status to deployment metrics family
* Depicts number of readyReplicas across all replicas sets owned by the deployment

Signed-off-by: Akshit Grover <akshit.grover2016@gmail.com>

internal/store/deployment.go

@@ -73,6 +73,21 @@ func deploymentMetricFamilies(allowLabelsList []string) []generator.FamilyGenera
 				}
 			}),
 		),
+		*generator.NewFamilyGenerator(
+			"kube_deployment_status_ready_replicas",
+			"The number of ready replicas per deployment.",
+			metric.Gauge,
+			"",
+			wrapDeploymentFunc(func(d *v1.Deployment) *metric.Family {
+				return &metric.Family{
+					Metrics: []*metric.Metric{
+						{
+							Value: float64(d.Status.ReadyReplicas),
+						},
+					},
+				}
+			}),
+		),
 		*generator.NewFamilyGenerator(
 			"kube_deployment_status_replicas_available",
 			"The number of available replicas per deployment.",

internal/store/deployment_test.go

@@ -53,6 +53,8 @@ func TestDeploymentStore(t *testing.T) {
 		# TYPE kube_deployment_spec_replicas gauge
 		# HELP kube_deployment_status_replicas The number of replicas per deployment.
 		# TYPE kube_deployment_status_replicas gauge
+		# HELP kube_deployment_status_ready_replicas The number of ready replicas per deployment.
+		# TYPE kube_deployment_status_ready_replicas gauge
 		# HELP kube_deployment_status_replicas_available The number of available replicas per deployment.
 		# TYPE kube_deployment_status_replicas_available gauge
 		# HELP kube_deployment_status_replicas_unavailable The number of unavailable replicas per deployment.
@@ -84,6 +86,7 @@ func TestDeploymentStore(t *testing.T) {
 				},
 				Status: v1.DeploymentStatus{
 					Replicas:            15,
+					ReadyReplicas:       10,
 					AvailableReplicas:   10,
 					UnavailableReplicas: 5,
 					UpdatedReplicas:     2,
@@ -116,6 +119,7 @@ func TestDeploymentStore(t *testing.T) {
         kube_deployment_status_replicas_unavailable{deployment="depl1",namespace="ns1"} 5
         kube_deployment_status_replicas_updated{deployment="depl1",namespace="ns1"} 2
         kube_deployment_status_replicas{deployment="depl1",namespace="ns1"} 15
+        kube_deployment_status_ready_replicas{deployment="depl1",namespace="ns1"} 10
         kube_deployment_status_condition{deployment="depl1",namespace="ns1",condition="Available",status="true"} 1
         kube_deployment_status_condition{deployment="depl1",namespace="ns1",condition="Progressing",status="true"} 1
         kube_deployment_status_condition{deployment="depl1",namespace="ns1",condition="Available",status="false"} 0
@@ -136,6 +140,7 @@ func TestDeploymentStore(t *testing.T) {
 				},
 				Status: v1.DeploymentStatus{
 					Replicas:            10,
+					ReadyReplicas:       5,
 					AvailableReplicas:   5,
 					UnavailableReplicas: 0,
 					UpdatedReplicas:     1,
@@ -169,6 +174,7 @@ func TestDeploymentStore(t *testing.T) {
         kube_deployment_status_replicas_unavailable{deployment="depl2",namespace="ns2"} 0
         kube_deployment_status_replicas_updated{deployment="depl2",namespace="ns2"} 1
         kube_deployment_status_replicas{deployment="depl2",namespace="ns2"} 10
+        kube_deployment_status_ready_replicas{deployment="depl2",namespace="ns2"} 5
         kube_deployment_status_condition{deployment="depl2",namespace="ns2",condition="Available",status="true"} 0
         kube_deployment_status_condition{deployment="depl2",namespace="ns2",condition="Progressing",status="true"} 0
         kube_deployment_status_condition{deployment="depl2",namespace="ns2",condition="ReplicaFailure",status="true"} 1