RKE2-COREDNS host file cannot be detected by pods.

[cengizhanR]

I edit rke2-coredns's config map and add hosts block.However, My pod's dont detect this config. I redeploy coredns and my pods. However, ı cant see my config on pods's host file.

apiVersion: v1
data:
  Corefile: |-
    .:53 {
        errors 
        health  {
            lameduck 5s
        }
        hosts {
          10.0.0.14 nfs.rancher.exemple.com
          fallthrough
        }
        ready 
        kubernetes   cluster.local  cluster.local in-addr.arpa ip6.arpa {
            pods insecure
            fallthrough in-addr.arpa ip6.arpa
            ttl 30
        }
        prometheus   0.0.0.0:9153
        forward   . /etc/resolv.conf
        cache   30
        loop 
        reload 
        loadbalance 
    }
kind: ConfigMap
metadata:
  annotations:
    meta.helm.sh/release-name: rke2-coredns
    meta.helm.sh/release-namespace: kube-system
  creationTimestamp: '2024-05-17T10:58:45Z'
  labels:
    app.kubernetes.io/instance: rke2-coredns
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: rke2-coredns
    helm.sh/chart: rke2-coredns-1.29.002
    k8s-app: kube-dns
    kubernetes.io/cluster-service: 'true'
    kubernetes.io/name: CoreDNS
  managedFields:
    - apiVersion: v1
      fieldsType: FieldsV1
      fieldsV1:
        f:data: {}
        f:metadata:
          f:annotations:
            .: {}
            f:meta.helm.sh/release-name: {}
            f:meta.helm.sh/release-namespace: {}
          f:labels:
            .: {}
            f:app.kubernetes.io/instance: {}
            f:app.kubernetes.io/managed-by: {}
            f:app.kubernetes.io/name: {}
            f:helm.sh/chart: {}
            f:k8s-app: {}
            f:kubernetes.io/cluster-service: {}
            f:kubernetes.io/name: {}
      manager: helm
      operation: Update
      time: '2024-05-17T10:58:45Z'
    - apiVersion: v1
      fieldsType: FieldsV1
      fieldsV1:
        f:data:
          f:Corefile: {}
      manager: rancher
      operation: Update
      time: '2024-07-08T14:43:19Z'
  name: rke2-coredns-rke2-coredns
  namespace: kube-system
  resourceVersion: '26636866'
  uid: 2b159962-e64f-4a02-935c-626915ef632c

root@nginx-deployment-568d9c746f-llfdh:/# cat /etc/hosts 
# Kubernetes-managed hosts file.
127.0.0.1       localhost
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
fe00::0 ip6-mcastprefix
fe00::1 ip6-allnodes
fe00::2 ip6-allrouters
10.42.1.38      nginx-deployment-568d9c746f-llfdh

[cengizhanR]

Should i add this config by using helm chart ?

[cengizhanR]

Is this work ?
/var/lib/rancher/rke2/server/manifests/rke2-coredns-config.yaml

apiVersion: helm.cattle.io/v1
kind: HelmChartConfig
metadata:
  name: rke2-coredns
  namespace: kube-system
spec:
  valuesContent: |-
    coreDNS:
      Corefile: |-
        .:53 {
            errors
            health {
                lameduck 5s
            }
            hosts {
                10.0.0.14 nfs.rancher.example.com
                fallthrough
            }
            ready
            kubernetes cluster.local in-addr.arpa ip6.arpa {
                pods insecure
                fallthrough in-addr.arpa ip6.arpa
                ttl 30
            }
            prometheus 0.0.0.0:9153
            forward . /etc/resolv.conf
            cache 30
            loop
            reload
            loadbalance
        }

[cengizhanR]

@brandond hello, If you have any ideas about this, I would be very happy if you could help me.

[manuelbuil]

What RKE2 version are you using?

[cengizhanR]

@manuelbuil Thank you for your return. I am using Kubernetes Version: v1.30.0 +rke2r1. I understand the problem here. My mistake, coreDns was not writing this configuration to the host files of the pods.
When I check inside pod, I saw its working. Thank you

/ # cat /etc/hosts 
# Kubernetes-managed hosts file.
127.0.0.1       localhost
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
fe00::0 ip6-mcastprefix
fe00::1 ip6-allnodes
fe00::2 ip6-allrouters
10.42.1.85      busybox
/ # nslookup nfs.rancher.exemple.com
Server:         10.43.0.10
Address:        10.43.0.10:53


Name:   nfs.rancher.exemple.com
Address: 10.0.0.14