基于 Kubernetes v1.14.0 之 CoreDNS部署
作者：互联网
1、部署容器前说明：
1.1、如果没有特殊指明，本文档的所有操作均在 k8s-operation 节点上执行；
kuberntes 自带插件的 manifests yaml 文件使用 gcr.io 的 docker registry，国内被墙，需要手动替换为其它 registry 地址；
1.2、由于k8s-master 没有部署容器服务于路由服务，但是k8s-master 又要访问容器网络跟k8s集群网络，1、在上级路由器写入静态路由让其能访问容器网络与k8s集群网络。2、在k8s-master 服务器写入静态路由。 以k8s-master 服务器写入静态路由为例：
ip route add 10.48.0.0/12 via 192.168.31.252
ip route add 10.64.0.0/16 via 192.168.31.252
加入重启服务器自动写入路由：
vim /etc/rc.local
chmod +x /etc/rc.local
192.168.31.252 为k8s-vip ip 由于vip ip安装了容器服务与路由服务
上级路由器写入让外面访问整个容器网络建议也写vip ip 这样坏掉一台第二台可以直接接管所以的配置可以不用更换1.3、配置k8s-vip 与k8s-ingress 不参与调度
kubectl cordon k8s-vip-01
kubectl cordon k8s-vip-02
kubectl cordon k8s-ingress-01
kubectl cordon k8s-ingress-02
2、CoreDNS 准备
cd /apps/work/k8s/kubernetes
tar -xvf kubernetes-src.tar.gz
cd cluster/addons/dns/coredns3、修改CoreDNS 配置
export CLUSTER_DNS_DOMAIN="niuke.local"
export CLUSTER_DNS_SVC_IP="10.64.0.2"
sed -i -e "s/__PILLAR__DNS__DOMAIN__/${CLUSTER_DNS_DOMAIN}/" -e "s/__PILLAR__DNS__SERVER__/${CLUSTER_DNS_SVC_IP}/" coredns.yaml
vi coredns.yaml
替换成
image: coredns/coredns
删除 loop 4、coredns.yaml
# __MACHINE_GENERATED_WARNING__
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
---
apiVersion: v1
kind: ConfigMap
metadata:
name: coredns
namespace: kube-system
labels:
addonmanager.kubernetes.io/mode: EnsureExists
data:
Corefile: |
.:53 {
errors
health
kubernetes niuke.local in-addr.arpa ip6.arpa {
pods insecure
upstream
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
forward . /etc/resolv.conf
cache 30
reload
loadbalance
}
---
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:
# replicas: not specified here:
# 1. In order to make Addon Manager do not reconcile this replicas parameter.
# 2. Default is 1.
# 3. Will be tuned in real time if DNS horizontal auto-scaling is turned on.
replicas: 3
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:
priorityClassName: system-cluster-critical
serviceAccountName: coredns
tolerations:
- key: "CriticalAddonsOnly"
operator: "Exists"
nodeSelector:
beta.kubernetes.io/os: linux
containers:
- name: coredns
image: coredns/coredns
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
readinessProbe:
httpGet:
path: /health
port: 8080
scheme: HTTP
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
---
apiVersion: v1
kind: Service
metadata:
name: kube-dns
namespace: kube-system
annotations:
prometheus.io/port: "9153"
prometheus.io/scrape: "true"
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
kubernetes.io/name: "CoreDNS"
spec:
selector:
k8s-app: kube-dns
clusterIP: 10.64.0.2
ports:
- name: dns
port: 53
protocol: UDP
- name: dns-tcp
port: 53
protocol: TCP
- name: metrics
port: 9153
protocol: TCP5、创建CoreDNS 自动横向扩容基于请求数 后期执行
vi hpa-coredns.yaml
apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
name: coredns
namespace: kube-system
spec:
scaleTargetRef:
apiVersion: extensions/v1beta1
kind: Deployment
name: coredns
minReplicas: 3
maxReplicas: 10
metrics:
- type: Pods
pods:
metricName: coredns_dns_request_count
targetAverageValue: 10006、创建CoreDNS 服务
kubectl create -f coredns.yaml7、检查CoreDNS 功能
kubectl get all -n kube-system
[root@jenkins coredns]# kubectl get all -n kube-system
NAME READY STATUS RESTARTS AGE
pod/coredns-6cbf85dbc6-hcqd7 1/1 Running 1 47d
pod/coredns-6cbf85dbc6-rdcww 1/1 Running 0 2d18h
pod/coredns-6cbf85dbc6-wcqmd 1/1 Running 0 32d
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kube-dns ClusterIP 10.64.0.2 <none> 53/UDP,53/TCP,9153/TCP 47d
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/coredns 3/3 3 3 47d
NAME DESIRED CURRENT READY AGE
replicaset.apps/coredns-6cbf85dbc6 3 3 3 47d
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
horizontalpodautoscaler.autoscaling/coredns Deployment/coredns 11%/80% 2 10 3 53d新建一个 Deployment
kubectl run myip --image=cloudnativelabs/whats-my-ip --replicas=3 --port=8080
export 该 Deployment, 生成 myip 服务：
kubectl expose deployment myip --port=8080 --target-port=8080 --type=NodePort
kubectl get pod -o wide
kubectl get services --all-namespaces
说明：k8s-vip 主要提供以后监控，等内部访问，主要基于dns+nginx 对外提供业务暴露访问
修改k8s-vip /etc/resolv.conf
options ndots:5
; generated by /usr/sbin/dhclient-script
nameserver 10.64.0.2
search kube-system.svc.niuke.local svc.niuke.local niuke.local安装 yum install -y bind-utils
测试CoreDNS 服务是否正常
[root@nginx-1 src]# dig @10.64.0.2 www.baid.com
; <<>> DiG 9.9.4-RedHat-9.9.4-73.el7_6 <<>> @10.64.0.2 www.baid.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9443
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.baid.com. IN A
;; ANSWER SECTION:
www.baid.com. 30 IN A 47.254.33.193
;; Query time: 38 msec
;; SERVER: 10.64.0.2#53(10.64.0.2)
;; WHEN: Tue Jun 11 10:04:17 CST 2019
;; MSG SIZE rcvd: 69查询刚刚建立myip 服务是否能解析
[root@nginx-1 src]# dig @10.64.0.2 myip.default.svc.niuke.local
; <<>> DiG 9.9.4-RedHat-9.9.4-73.el7_6 <<>> @10.64.0.2 myip.default.svc.niuke.local
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62331
;; flags: qr rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;myip.default.svc.niuke.local. IN A
;; ANSWER SECTION:
myip.default.svc.niuke.local. 1 IN A 10.64.160.236
;; Query time: 1 msec
;; SERVER: 10.64.0.2#53(10.64.0.2)
;; WHEN: Tue Jun 11 10:06:13 CST 2019
;; MSG SIZE rcvd: 101
curl myip.default.svc.niuke.local:8080
[root@nginx-1 src]# curl myip.default.svc.niuke.local:8080
HOSTNAME:myip-7ddc5b85f4-6h47f IP:10.65.1.250
[root@nginx-1 src]# curl myip.default.svc.niuke.local:8080
HOSTNAME:myip-7ddc5b85f4-69jlx IP:10.65.4.243
[root@nginx-1 src]# curl myip.default.svc.niuke.local:8080
HOSTNAME:myip-7ddc5b85f4-9wxd4 IP:10.65.3.149
解析正常也能正常访问下一篇： Kubernetes 生产环境安装部署 基于 Kubernetes v1.14.0 之 kubernetes-dashboard部署
标签：kube,name,Kubernetes,v1.14,io,coredns,kubernetes,CoreDNS,k8s 来源： https://blog.51cto.com/juestnow/2407119