1.说明
coredns在kubernetes中被归为addon,作为附加组件,支持容器化部署
2.部署
- DNS的配置(coredns-cm.yml)
apiVersion: v1
kind: ConfigMap
metadata:
name: coredns
namespace: kube-system
labels:
addonmanager.kubernetes.io/mode: EnsureExists
data:
Corefile: |
.:53 {
errors
health
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
upstream
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
proxy . /etc/resolv.conf
cache 30
loop
reload
loadbalance
}
- DNS的RABC权限(coredns-rabc.yml)
apiVersion: v1
kind: ServiceAccount
metadata:
name: coredns
namespace: kube-system
labels:
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
labels:
kubernetes.io/bootstrapping: rbac-defaults
addonmanager.kubernetes.io/mode: Reconcile
name: system:coredns
rules:
- apiGroups:
- ""
resources:
- endpoints
- services
- pods
- namespaces
verbs:
- list
- watch
- apiGroups:
- ""
resources:
- nodes
verbs:
- get
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
annotations:
rbac.authorization.kubernetes.io/autoupdate: "true"
labels:
kubernetes.io/bootstrapping: rbac-defaults
addonmanager.kubernetes.io/mode: EnsureExists
name: system:coredns
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: system:coredns
subjects:
- kind: ServiceAccount
name: coredns
namespace: kube-system
- DNS的编排脚本(coredns-dp.yml)
apiVersion: apps/v1
kind: Deployment
metadata:
name: coredns
namespace: kube-system
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
kubernetes.io/name: "CoreDNS"
spec:
strategy:
type: RollingUpdate
rollingUpdate:
maxUnavailable: 1
selector:
matchLabels:
k8s-app: kube-dns
template:
metadata:
labels:
k8s-app: kube-dns
annotations:
seccomp.security.alpha.kubernetes.io/pod: 'docker/default'
spec:
serviceAccountName: coredns
tolerations:
- key: "CriticalAddonsOnly"
operator: "Exists"
containers:
- name: coredns
image: k8s.gcr.io/coredns:1.2.6
imagePullPolicy: IfNotPresent
resources:
limits:
memory: 170Mi
requests:
cpu: 100m
memory: 70Mi
args: [ "-conf", "/etc/coredns/Corefile" ]
volumeMounts:
- name: config-volume
mountPath: /etc/coredns
readOnly: true
ports:
- containerPort: 53
name: dns
protocol: UDP
- containerPort: 53
name: dns-tcp
protocol: TCP
- containerPort: 9153
name: metrics
protocol: TCP
livenessProbe:
httpGet:
path: /health
port: 8080
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
securityContext:
allowPrivilegeEscalation: false
capabilities:
add:
- NET_BIND_SERVICE
drop:
- all
readOnlyRootFilesystem: true
dnsPolicy: Default
volumes:
- name: config-volume
configMap:
name: coredns
items:
- key: Corefile
path: Corefile
- DNS的服务暴露(coredns-svc.yml)
apiVersion: v1
kind: Service
metadata:
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
kubernetes.io/name: KubeDNS
name: kube-dns
namespace: kube-system
spec:
clusterIP: 10.254.0.2
ports:
- name: dns
port: 53
protocol: UDP
targetPort: 53
- name: dns-tcp
port: 53
protocol: TCP
targetPort: 53
- name: dns-metrics
port: 9153
protocol: TCP
targetPort: 9153
selector:
k8s-app: kube-dns
type: ClusterIP
3.测试
kubectl run curl --image=radial/busyboxplus:curl -i --tty
#验证
[ root@curl-87b54756-fpsvt:/ ]$ nslookup kubernetes.default
Server: 10.254.0.2
Address 1: 10.254.0.2 kube-dns.kube-system.svc.cluster.local
Name: kubernetes.default
Address 1: 10.254.0.1 kubernetes.default.svc.cluster.local
[ root@curl-87b54756-fpsvt:/ ]$ curl kubernetes.default.svc.cluster.local
curl: (7) Failed to connect to kubernetes.default.svc.cluster.local port 80: Connection refused
[ root@curl-87b54756-fpsvt:/ ]$ curl kubernetes.default.svc.cluster.local:443
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