AKS - Create dedicated kubernetes service to expose CoreDNS metrics

[rgarcia89]

Description

Currently the kube-prometheus-stack creates a ServiceMonitor to collect the coredns metrics of a Kubernetes Service which is not exposing them. This is caused by the fact that AKS is not exposing the metrics port by default on the kube-dns service.

In order not to have to patch the service manually, I suggest the creation of a dedicated service in case that the platform is set to aks.

AKS kube-dns service definition:

Name:              kube-dns
Namespace:         kube-system
Labels:            addonmanager.kubernetes.io/mode=Reconcile
                   k8s-app=kube-dns
                   kubernetes.io/cluster-service=true
                   kubernetes.io/name=CoreDNS
Annotations:       <none>
Selector:          k8s-app=kube-dns
Type:              ClusterIP
IP Family Policy:  SingleStack
IP Families:       IPv4
IP:                10.0.0.10
IPs:               10.0.0.10
Port:              dns  53/UDP
TargetPort:        53/UDP
Endpoints:         10.244.4.33:53,10.244.6.49:53
Port:              dns-tcp  53/TCP
TargetPort:        53/TCP
Endpoints:         10.244.4.33:53,10.244.6.49:53
Session Affinity:  None
Events:            <none>

Code section where we create the CoreDNS ServiceMonitor

kube-prometheus/jsonnet/kube-prometheus/components/k8s-control-plane.libsonnet

Line 315 in c9e1145

serviceMonitorCoreDNS: {

Type of change

What type of changes does your code introduce to the kube-prometheus? Put an x in the box that apply.

• CHANGE (fix or feature that would cause existing functionality to not work as expected)
• FEATURE (non-breaking change which adds functionality)
• BUGFIX (non-breaking change which fixes an issue)
• ENHANCEMENT (non-breaking change which improves existing functionality)
• NONE (if none of the other choices apply. Example, tooling, build system, CI, docs, etc.)

Changelog entry

Added kubernetes service creation for AKS platform to expose CoreDNS metrics