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docs(core-dns): update tutorial (#5926)
* docs(core-dns): update tutorial Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com> * docs(core-dns): update tutorial Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com> * docs(core-dns): update tutorial Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com> * docs(core-dns): update tutorial Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com> * docs(core-dns): update tutorial Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com> * docs(core-dns): update tutorial Co-authored-by: Michel Loiseleur <97035654+mloiseleur@users.noreply.github.com> --------- Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com> Co-authored-by: Michel Loiseleur <97035654+mloiseleur@users.noreply.github.com>
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‎docs/snippets/tutorials/coredns/coredns-groups.yaml‎

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---
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apiVersion: v1
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kind: Service
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metadata:
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name: a
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annotations:
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external-dns.alpha.kubernetes.io/hostname: a.domain.local
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external-dns.alpha.kubernetes.io/coredns-group: "g1"
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spec:
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type: LoadBalancer
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status:
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loadBalancer:
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ingress:
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- ip: 127.0.0.1
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---
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apiVersion: v1
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kind: Service
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metadata:
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name: b
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annotations:
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external-dns.alpha.kubernetes.io/hostname: b.domain.local
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external-dns.alpha.kubernetes.io/coredns-group: "g1"
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spec:
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type: LoadBalancer
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status:
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loadBalancer:
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ingress:
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- ip: 127.0.0.2
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---
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apiVersion: v1
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kind: Service
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metadata:
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name: c
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annotations:
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external-dns.alpha.kubernetes.io/hostname: c.subdom.domain.local
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external-dns.alpha.kubernetes.io/coredns-group: "g2"
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spec:
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type: LoadBalancer
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status:
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loadBalancer:
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ingress:
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- ip: 127.0.0.3
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---
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apiVersion: v1
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kind: Service
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metadata:
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name: d
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annotations:
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external-dns.alpha.kubernetes.io/hostname: d.subdom.domain.local
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external-dns.alpha.kubernetes.io/coredns-group: "g2"
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spec:
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type: LoadBalancer
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status:
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loadBalancer:
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ingress:
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- ip: 127.0.0.4

‎docs/snippets/tutorials/coredns/etcd.yaml‎

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# kubectl apply -f docs/snippets/tutorials/coredns/etcd.yaml
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# kubectl delete -f docs/snippets/tutorials/coredns/etcd.yaml
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---
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apiVersion: v1
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kind: Service
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metadata:
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name: etcd
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namespace: default
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spec:
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type: ClusterIP
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clusterIP: None
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ports:
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- name: etcd-client
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port: 2379
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- name: etcd-server
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port: 2380
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- name: etcd-metrics
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port: 8080
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selector:
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app: etcd
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---
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apiVersion: v1
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kind: Service
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metadata:
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name: etcd-nodeport-external
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namespace: default
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spec:
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type: NodePort
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ports:
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- port: 2379
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targetPort: 2379
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nodePort: 32379 # must match kind config port mapping
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selector:
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app: etcd
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---
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apiVersion: apps/v1
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kind: StatefulSet
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metadata:
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name: etcd
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namespace: default
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spec:
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serviceName: etcd
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replicas: 1
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selector:
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matchLabels:
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app: etcd
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template:
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metadata:
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labels:
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app: etcd
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annotations:
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serviceName: etcd
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spec:
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containers:
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- name: etcd
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image: quay.io/coreos/etcd:v3.5.15
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command:
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- /usr/local/bin/etcd
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- --name=$(HOSTNAME)
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- --listen-peer-urls=$(URI_SCHEME)://0.0.0.0:2380
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- --listen-client-urls=$(URI_SCHEME)://0.0.0.0:2379
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- --advertise-client-urls=$(URI_SCHEME)://$(HOSTNAME).$(SERVICE_NAME):2379
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- --data-dir=/var/lib/etcd
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ports:
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- containerPort: 2379
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volumeMounts:
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- name: data
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mountPath: /var/lib/etcd
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env:
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- name: K8S_NAMESPACE
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valueFrom:
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fieldRef:
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fieldPath: metadata.namespace
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- name: HOSTNAME
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valueFrom:
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fieldRef:
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fieldPath: metadata.name
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- name: SERVICE_NAME
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valueFrom:
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fieldRef:
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fieldPath: metadata.annotations['serviceName']
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- name: ETCDCTL_ENDPOINTS
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value: $(HOSTNAME).$(SERVICE_NAME):2379
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- name: URI_SCHEME
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value: "http"
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volumeClaimTemplates:
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- metadata:
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name: data
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spec:
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accessModes: ["ReadWriteOnce"]
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resources:
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requests:
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storage: 50Mi

‎docs/snippets/tutorials/coredns/fixtures.yaml‎

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# kubectl apply -f docs/snippets/tutorials/coredns/fixtures.yaml
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# kubectl delete -f docs/snippets/tutorials/coredns/fixtures.yaml
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# kubectl get svc -l svc=test-svc
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---
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apiVersion: v1
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kind: Service
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metadata:
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name: a-g1-record
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labels:
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svc: test-svc
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annotations:
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external-dns.alpha.kubernetes.io/hostname: a.example.org
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external-dns.alpha.kubernetes.io/coredns-group: "g1"
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cluster-name: "cluster1"
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namespace: default
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spec:
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type: LoadBalancer
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ports:
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- port: 80
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name: http
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targetPort: 80
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selector:
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app: test-app
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---
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apiVersion: v1
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kind: Service
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metadata:
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name: aa-g1-record
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labels:
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svc: test-svc
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annotations:
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external-dns.alpha.kubernetes.io/hostname: aa.example.org
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external-dns.alpha.kubernetes.io/coredns-group: "g1"
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cluster-name: "cluster1"
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namespace: default
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spec:
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type: LoadBalancer
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ports:
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- port: 80
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name: http
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targetPort: 80
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selector:
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app: test-app

‎docs/snippets/tutorials/coredns/kind.yaml‎

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# ref: https://kind.sigs.k8s.io/docs/user/quick-start/
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# https://kind.sigs.k8s.io/docs/user/configuration/#extra-port-mappings
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# kind create cluster --config=docs/snippets/tutorials/coredns/kind.yaml
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# kind delete cluster --name coredns-etcd
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# kubectl cluster-info --context kind-coredns-etcd
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# kubectl get nodes -o wide
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---
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kind: Cluster
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apiVersion: kind.x-k8s.io/v1alpha4
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name: coredns-etcd
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networking:
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apiServerAddress: 127.0.0.1
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apiServerPort: 6443
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nodes:
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- role: control-plane
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image: kindest/node:v1.33.0
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kubeadmConfigPatches:
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- |
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kind: InitConfiguration
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nodeRegistration:
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kubeletExtraArgs:
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node-labels: "ingress-ready=true"
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extraPortMappings:
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- containerPort: 80
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hostPort: 8080
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listenAddress: "0.0.0.0"
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protocol: TCP
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- containerPort: 43
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hostPort: 4443
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listenAddress: "0.0.0.0"
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protocol: TCP
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- containerPort: 32379 # inside kind node
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hostPort: 32379 # exposed on host
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listenAddress: "0.0.0.0"
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protocol: TCP
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- role: worker
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image: kindest/node:v1.33.0

‎docs/snippets/tutorials/coredns/values-coredns.yaml‎

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# kubectl logs deploy/coredns -n default -c coredns
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# ref: https://github.com/coredns/helm/blob/master/charts/coredns/values.yaml
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isClusterService: false
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service:
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name: coredns
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port: 53
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annotations: {}
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clusterIP: ""
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# Main customization
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servers:
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- zones:
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- zone: .
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port: 53
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plugins:
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- name: errors
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- name: debug # <── enables debug mode
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- name: health
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configBlock: |-
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lameduck 5s
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- name: ready
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# to query kubernetes API for data
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- name: kubernetes
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parameters: cluster.local 10.0.0.0/24
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configBlock: |-
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pods insecure
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fallthrough in-addr.arpa ip6.arpa
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ttl 30
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- name: etcd
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parameters: "example.org"
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configBlock: |
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stubzones
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path /skydns
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endpoint http://etcd.default.svc.cluster.local:2379
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fallthrough
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- name: log # <── log each DNS query
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- name: forward
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parameters: ". /etc/resolv.conf"
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- name: cache
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parameters: 30
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- name: reload
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- name: loop
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- name: loadbalance
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replicaCount: 1
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# required to debug DNS resolution from within CoreDNS pods
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# kubectl logs deploy/coredns -n default -c resolv-check --tail=50
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initContainers:
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- name: resolv-check
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image: busybox:1.37
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command: ["sh", "-c", "echo '--- /etc/resolv.conf ---'; cat /etc/resolv.conf; echo '---------------------------'; nslookup kubernetes.default.svc.cluster.local || true; sleep 5"]

‎docs/snippets/tutorials/coredns/values-extdns-coredns.yaml‎

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# ref: https://github.com/kubernetes-sigs/external-dns/blob/master/charts/external-dns/values.yaml
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provider:
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name: coredns
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env:
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- name: ETCD_URLS
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value: "http://etcd.default.svc.cluster.local:2379"
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txtOwnerId: cluster1
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# Filter resources queried for endpoints by annotation, using label selector semantics
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annotationFilter: cluster-name=cluster1
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domainFilters:
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- example.org
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# Sources define what ExternalDNS will use to discover endpoints
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sources:
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- service
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# Policy options
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policy: sync
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logLevel: debug
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interval: 1m
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# RBAC configuration
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rbac:
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create: true
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# Optional: tune resource requests
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resources:
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requests:
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cpu: 100m
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memory: 64Mi
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limits:
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cpu: 200m
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memory: 128Mi

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