Jimmy Song
GitHub
commit
1975470f9e
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@ -130,7 +130,9 @@
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- [网络和集群性能测试](practice/network-and-cluster-perfermance-test.md)
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- [边缘节点配置](practice/edge-node-configuration.md)
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- [安装Nginx ingress](practice/nginx-ingress-installation.md)
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- [配置内置DNS（kube-dns）](practice/configuring-dns.md)
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- [安装配置DNS]
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- [Kube-DNS](practice/configuring-dns.md)
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- [Core-DNS](practice/coredns.md)
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- [运维管理](practice/operation.md)
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- [Master节点高可用](practice/master-ha.md)
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- [服务滚动升级](practice/service-rolling-update.md)
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@ -0,0 +1,145 @@
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apiVersion: v1
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kind: ServiceAccount
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metadata:
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name: coredns
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namespace: kube-system
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---
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apiVersion: rbac.authorization.k8s.io/v1beta1
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kind: ClusterRole
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metadata:
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labels:
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kubernetes.io/bootstrapping: rbac-defaults
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name: system:coredns
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rules:
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- apiGroups:
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- ""
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resources:
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- endpoints
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- services
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- pods
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- namespaces
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verbs:
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- list
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- watch
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---
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apiVersion: rbac.authorization.k8s.io/v1beta1
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kind: ClusterRoleBinding
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metadata:
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annotations:
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rbac.authorization.kubernetes.io/autoupdate: "true"
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labels:
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kubernetes.io/bootstrapping: rbac-defaults
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name: system:coredns
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roleRef:
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apiGroup: rbac.authorization.k8s.io
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kind: ClusterRole
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name: system:coredns
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subjects:
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- kind: ServiceAccount
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name: coredns
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namespace: kube-system
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---
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: coredns
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namespace: kube-system
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data:
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Corefile: |
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.:53 {
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errors
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health
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kubernetes CLUSTER_DOMAIN REVERSE_CIDRS {
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pods insecure
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upstream
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fallthrough in-addr.arpa ip6.arpa
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}
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prometheus :9153
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proxy . /etc/resolv.conf
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cache 30
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}
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---
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apiVersion: extensions/v1beta1
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kind: Deployment
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metadata:
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name: coredns
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namespace: kube-system
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labels:
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k8s-app: kube-dns
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kubernetes.io/name: "CoreDNS"
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spec:
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replicas: 2
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strategy:
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type: RollingUpdate
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rollingUpdate:
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maxUnavailable: 1
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selector:
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matchLabels:
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k8s-app: kube-dns
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template:
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metadata:
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labels:
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k8s-app: kube-dns
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spec:
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serviceAccountName: coredns
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tolerations:
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- key: "CriticalAddonsOnly"
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operator: "Exists"
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containers:
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- name: coredns
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image: coredns/coredns:1.1.1
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imagePullPolicy: IfNotPresent
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args: [ "-conf", "/etc/coredns/Corefile" ]
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volumeMounts:
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- name: config-volume
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mountPath: /etc/coredns
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ports:
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- containerPort: 53
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name: dns
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protocol: UDP
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- containerPort: 53
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name: dns-tcp
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protocol: TCP
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- containerPort: 9153
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name: metrics
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protocol: TCP
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livenessProbe:
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httpGet:
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path: /health
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port: 8080
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scheme: HTTP
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initialDelaySeconds: 60
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timeoutSeconds: 5
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successThreshold: 1
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failureThreshold: 5
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dnsPolicy: Default
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volumes:
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- name: config-volume
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configMap:
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name: coredns
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items:
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- key: Corefile
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path: Corefile
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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: kube-dns
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namespace: kube-system
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annotations:
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prometheus.io/scrape: "true"
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labels:
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k8s-app: kube-dns
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kubernetes.io/cluster-service: "true"
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kubernetes.io/name: "CoreDNS"
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spec:
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selector:
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k8s-app: kube-dns
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clusterIP: CLUSTER_DNS_IP
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ports:
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- name: dns
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port: 53
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protocol: UDP
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- name: dns-tcp
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port: 53
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protocol: TCP
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@ -0,0 +1,52 @@
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#!/bin/bash
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# Deploys CoreDNS to a cluster currently running Kube-DNS.
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show_help () {
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cat << USAGE
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usage: $0 [ -r REVERSE-CIDR ] [ -i DNS-IP ] [ -d CLUSTER-DOMAIN ] [ -t YAML-TEMPLATE ]
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-r : Define a reverse zone for the given CIDR. You may specifcy this option more
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than once to add multiple reverse zones. If no reverse CIDRs are defined,
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then the default is to handle all reverse zones (i.e. in-addr.arpa and ip6.arpa)
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-i : Specify the cluster DNS IP address. If not specificed, the IP address of
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the existing "kube-dns" service is used, if present.
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USAGE
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exit 0
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}
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# Simple Defaults
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CLUSTER_DOMAIN=cluster.local
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YAML_TEMPLATE=`pwd`/coredns.yaml.sed
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# Get Opts
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while getopts "hr:i:d:t:" opt; do
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case "$opt" in
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h) show_help
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;;
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r) REVERSE_CIDRS="$REVERSE_CIDRS $OPTARG"
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;;
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i) CLUSTER_DNS_IP=$OPTARG
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;;
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d) CLUSTER_DOMAIN=$OPTARG
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;;
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t) YAML_TEMPLATE=$OPTARG
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;;
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esac
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done
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# Conditional Defaults
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if [[ -z $REVERSE_CIDRS ]]; then
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REVERSE_CIDRS="in-addr.arpa ip6.arpa"
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fi
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if [[ -z $CLUSTER_DNS_IP ]]; then
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# Default IP to kube-dns IP
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CLUSTER_DNS_IP=$(kubectl get service --namespace kube-system kube-dns -o jsonpath="{.spec.clusterIP}")
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if [ $? -ne 0 ]; then
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>&2 echo "Error! The IP address for DNS service couldn't be determined automatically. Please specify the DNS-IP with the '-i' option."
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exit 2
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fi
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fi
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sed -e s/CLUSTER_DNS_IP/$CLUSTER_DNS_IP/g -e s/CLUSTER_DOMAIN/$CLUSTER_DOMAIN/g -e "s?REVERSE_CIDRS?$REVERSE_CIDRS?g" $YAML_TEMPLATE
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@ -0,0 +1,35 @@
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# Kubernetes中CoreDNS安装实践
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CoreDNS可以在具有标准的Kube-DNS的Kubernetes集群中运行。作为* Kubernetes *的插件使用，CoreDNS将从
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Kubernetes集群中读取区（zone）数据。它实现了为Kubernetes的DNS服务发现定义的规范：
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https://github.com/kubernetes/dns/blob/master/docs/specification.md
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## 部署CoreDNS需要使用到官方提供的两个文件 [deploy.sh](https://github.com/coredns/deployment/blob/master/kubernetes/deploy.sh)和[coredns.yaml.sed](https://github.com/coredns/deployment/blob/master/kubernetes/coredns.yaml.sed)
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(这两个文件已经放入manifest的[coredns](/manifests/coredns)中)
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`deploy.sh` 是一个用于在已经运行kube-dns的集群中生成运行CoreDNS部署文件（manifest）的工具脚本。它使用
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'coredns.yaml.sed'文件作为模板，创建一个ConfigMap和CoreDNS的deployment, 然后更新集群中已有的kube-dns
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服务的selector使用CoreDNS的deployment。重用已有的服务并不会在服务的请求中发生冲突。
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deploy.sh文件并不会删除kube-dns的deployment或者replication controller。如果要删除kube-dns, 你必须
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在部署CoreDNS后手动的删除kube-dns。
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你需要仔细测试manifest文件，以确保它能够对你的集群正常运行。这依赖于你的怎样构建你的集群以及你正在运行的集群版本。
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对manifest文件做一些修改是有比要的。
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在最佳的案例场景中，使用CoreDNS替换Kube-DNS只需要使用下面的两个命令：
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~~~
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$ ./deploy.sh | kubectl apply -f -
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$ kubectl delete --namespace=kube-system deployment kube-dns
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~~~
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注意：我们建议在部署CoreDNS后删除kube-dns。否则如果CoreDNS和kube-dns同时运行，服务查询可能会随机的在CoreDNS和kube-dns之间产生。
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对于non-RBAC部署，你需要编辑生成的结果yaml文件：
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1. 从yaml文件的“Deployment”部分删除 `serviceAccountName: coredns`
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2. 删除 `ServiceAccount`, `ClusterRole`, 和 `ClusterRoleBinding` 部分
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Reference in New Issue