[release-1.25] Allow adding configuration to coredns .:53 block via *.override keys in coredns-custom ConfigMap

[brandond]

• Allow adding configuration to coredns .:53 block via *.override keys in coredns-custom ConfigMap #7639 backport

[endawkins]

Validated on branch 1.25 with commit 582f07c / version 1.25

Environment Details

Infrastructure

• Cloud
• Hosted

Node(s) CPU architecture, OS, and Version:

Linux ip-172-31-30-17 5.19.0-1025-aws #26~22.04.1-Ubuntu SMP Mon Apr 24 01:58:15 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
PRETTY_NAME="Ubuntu 22.04.2 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.2 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=jammy

Cluster Configuration:

1 server, 1 agent (optional)

Config.yaml:

server:
cluster-init: true
write-kubeconfig-mode: 644

agent:
server: "https://<serverIP>:6443"
token: test

Additional files

cordons_customize.yaml:

apiVersion: v1
kind: ConfigMap
metadata:
  name: coredns-custom
  namespace: kube-system
data:
  log.override: |
    log
  custom.server: |
    why.local {
      forward . 127.0.0.1
    }

Testing Steps

1. Copy config.yaml

$ sudo mkdir -p /etc/rancher/k3s && sudo cp config.yaml /etc/rancher/k3s

2. Install k3s
3. Run the following commands:

k apply -f cordons_customize.yaml
k get configmaps --namespace=kube-system coredns -o yaml

Replication Results:

• k3s version used for replication:

v1.25.10+k3s1

ubuntu@ip-172-31-30-17:~$ kubectl get configmaps --namespace=kube-system coredns -o yaml
apiVersion: v1
data:
  Corefile: |
    .:53 {
        errors
        health
        ready
        kubernetes cluster.local in-addr.arpa ip6.arpa {
          pods insecure
          fallthrough in-addr.arpa ip6.arpa
        }
        hosts /etc/coredns/NodeHosts {
          ttl 60
          reload 15s
          fallthrough
        }
        prometheus :9153
        forward . /etc/resolv.conf
        cache 30
        loop
        reload
        loadbalance
    }
    import /etc/coredns/custom/*.server
  NodeHosts: |
    172.31.30.17 ip-172-31-30-17
    172.31.17.218 ip-172-31-17-218
kind: ConfigMap
metadata:
  annotations:
    objectset.rio.cattle.io/applied: H4sIAAAAAAAA/4yQwWrzMBCEX0Xs2fEf20nsX9BDybH02lMva2kdq1Z2g6SkBJN3L8IUCiVtbyNGOzvfzoAn90IhOmHQcKmgAIsJQc+wl0CD8wQaSr1t1PzKSilFIUiIix4JfRoXHQjtdZHTuafAlCgq488xUSi9wK2AybEFDXvhwR2e8QQFHCnh50ZkloTJCcf8lP6NTIqUyuCkNJiSp9LJP5czoLjryztTWB0uE2iYmvjFuVSFenJsHx6tFf41gvGY6Y0Eshz/9D2e0OSZfIJVvMZExwzusSf/I9SIcQQNvaG6a+r/XVdV7abBddPtsN9W66Eedi0N7aberM22zaHf6t0tcPsIAAD//8Ix+PfoAQAA
    objectset.rio.cattle.io/id: ""
    objectset.rio.cattle.io/owner-gvk: k3s.cattle.io/v1, Kind=Addon
    objectset.rio.cattle.io/owner-name: coredns
    objectset.rio.cattle.io/owner-namespace: kube-system
  creationTimestamp: "2023-06-23T02:56:49Z"
  labels:
    objectset.rio.cattle.io/hash: bce283298811743a0386ab510f2f67ef74240c57
  name: coredns
  namespace: kube-system
  resourceVersion: "859"
  uid: 07eae595-fed5-4f9e-aec6-7b31ac730e9d

Validation Results:

• k3s version used for validation:

k3s version v1.25.11-rc2+k3s1 (582f07cf)
go version go1.19.10

ubuntu@ip-172-31-30-17:~$ kubectl get configmaps --namespace=kube-system coredns -o yaml
apiVersion: v1
data:
  Corefile: |
    .:53 {
        errors
        health
        ready
        kubernetes cluster.local in-addr.arpa ip6.arpa {
          pods insecure
          fallthrough in-addr.arpa ip6.arpa
        }
        hosts /etc/coredns/NodeHosts {
          ttl 60
          reload 15s
          fallthrough
        }
        prometheus :9153
        forward . /etc/resolv.conf
        cache 30
        loop
        reload
        loadbalance
        import /etc/coredns/custom/*.override
    }
    import /etc/coredns/custom/*.server
  NodeHosts: |
    172.31.30.17 ip-172-31-30-17
    172.31.17.218 ip-172-31-17-218
kind: ConfigMap
metadata:
  annotations:
    objectset.rio.cattle.io/applied: H4sIAAAAAAAA/4yQwWrzMBCEX0Xs2fEf20nsX9BDybH02lMva2kdq1Z2g6SkBJN3L8IUCiVtbyNGOzvfzoAn90IhOmHQcKmgAIsJQc+wl0CD8wQaSr1t1PzKSilFIUiIix4JfRoXHQjtdZHTuafAlCgq488xUSi9wK2AybEFDXvhwR2e8QQFHCnh50ZkloTJCcf8lP6NTIqUyuCkNJiSp9LJP5czoLjryztTWB0uE2iYmvjFuVSFenJsHx6tFf41gvGY6Y0Eshz/9D2e0OSZfIJVvMZExwzusSf/I9SIcQQNvaG6a+r/XVdV7abBddPtsN9W66Eedi0N7aberM22zaHf6t0tcPsIAAD//8Ix+PfoAQAA
    objectset.rio.cattle.io/id: ""
    objectset.rio.cattle.io/owner-gvk: k3s.cattle.io/v1, Kind=Addon
    objectset.rio.cattle.io/owner-name: coredns
    objectset.rio.cattle.io/owner-namespace: kube-system
  creationTimestamp: "2023-06-23T03:43:00Z"
  labels:
    objectset.rio.cattle.io/hash: bce283298811743a0386ab510f2f67ef74240c57
  name: coredns
  namespace: kube-system
  resourceVersion: "585"
  uid: 67375e04-a3a2-4a74-8e46-d04d6cf6f020

Additional context / logs:

N/A