部署-Kubernetes DNS
创建DNS 用来自动对应主机和集群IP
直接创建yaml文件来创建dns
apiVersion: v1
kind: Service
metadata:
name: kube-dns
namespace: kube-system
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
kubernetes.io/name: "KubeDNS"
spec:
selector:
k8s-app: kube-dns
clusterIP: 10.0.0.2 #我们指定一个dns地址空的没用的ip,这个地址其实在node1,2的kubelet.config里有指定
ports:
- name: dns
port: 53
protocol: UDP
- name: dns-tcp
port: 53
protocol: TCP
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: kube-dns
namespace: kube-system
labels:
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
---
apiVersion: v1
kind: ConfigMap
metadata:
name: kube-dns
namespace: kube-system
labels:
addonmanager.kubernetes.io/mode: EnsureExists
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: kube-dns
namespace: kube-system
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
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.
strategy:
rollingUpdate:
maxSurge: 10%
maxUnavailable: 0
selector:
matchLabels:
k8s-app: kube-dns
template:
metadata:
labels:
k8s-app: kube-dns
annotations:
scheduler.alpha.kubernetes.io/critical-pod: ''
spec:
tolerations:
- key: "CriticalAddonsOnly"
operator: "Exists"
volumes:
- name: kube-dns-config
configMap:
name: kube-dns
optional: true
containers:
- name: kubedns
image: registry.cn-hangzhou.aliyuncs.com/google_containers/k8s-dns-kube-dns-amd64:1.14.7
resources:
# TODO: Set memory limits when we've profiled the container for large
# clusters, then set request = limit to keep this container in
# guaranteed class. Currently, this container falls into the
# "burstable" category so the kubelet doesn't backoff from restarting it.
limits:
memory: 170Mi
requests:
cpu: 100m
memory: 70Mi
livenessProbe:
httpGet:
path: /healthcheck/kubedns
port: 10054
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
readinessProbe:
httpGet:
path: /readiness
port: 8081
scheme: HTTP
# we poll on pod startup for the Kubernetes master service and
# only setup the /readiness HTTP server once that's available.
initialDelaySeconds: 3
timeoutSeconds: 5
args:
- --domain=cluster.local. # 这个名字是之前创建证书里创建的
- --dns-port=10053
- --config-dir=/kube-dns-config
- --v=2
env:
- name: PROMETHEUS_PORT
value: "10055"
ports:
- containerPort: 10053
name: dns-local
protocol: UDP
- containerPort: 10053
name: dns-tcp-local
protocol: TCP
- containerPort: 10055
name: metrics
protocol: TCP
volumeMounts:
- name: kube-dns-config
mountPath: /kube-dns-config
- name: dnsmasq
image: registry.cn-hangzhou.aliyuncs.com/google_containers/k8s-dns-dnsmasq-nanny-amd64:1.14.7
livenessProbe:
httpGet:
path: /healthcheck/dnsmasq
port: 10054
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
args:
- -v=2
- -logtostderr
- -configDir=/etc/k8s/dns/dnsmasq-nanny
- -restartDnsmasq=true
- --
- -k
- --cache-size=1000
- --no-negcache
- --log-facility=-
- --server=/cluster.local/127.0.0.1#10053
- --server=/in-addr.arpa/127.0.0.1#10053
- --server=/ip6.arpa/127.0.0.1#10053
ports:
- containerPort: 53
name: dns
protocol: UDP
- containerPort: 53
name: dns-tcp
protocol: TCP
# see: https://github.com/kubernetes/kubernetes/issues/29055 for details
resources:
requests:
cpu: 150m
memory: 20Mi
volumeMounts:
- name: kube-dns-config
mountPath: /etc/k8s/dns/dnsmasq-nanny
- name: sidecar
image: registry.cn-hangzhou.aliyuncs.com/google_containers/k8s-dns-sidecar-amd64:1.14.7
livenessProbe:
httpGet:
path: /metrics
port: 10054
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
args:
- --v=2
- --logtostderr
- --probe=kubedns,127.0.0.1:10053,kubernetes.default.svc.cluster.local,5,SRV
- --probe=dnsmasq,127.0.0.1:53,kubernetes.default.svc.cluster.local,5,SRV
ports:
- containerPort: 10054
name: metrics
protocol: TCP
resources:
requests:
memory: 20Mi
cpu: 10m
dnsPolicy: Default # Don't use cluster DNS.
serviceAccountName: kube-dns
kubectl apply -f kube-dns.yaml
查看一下pod是否已经正常运行
[root@node dns]# kubectl apply -f kube-dns.yaml ^C
[root@node dns]# kubectl get pod -o wide -n kube-system
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GAT
ESheapster-c679b85f9-bldkw 1/1 Running 0 27m 172.17.71.6 10.167.130.206 <none> <none>
kube-dns-5c74856c48-j44h4 3/3 Running 0 51m 172.17.71.8 10.167.130.206 <none> <none>
kubernetes-dashboard-7b79f98f97-wxkkc 1/1 Running 0 5d19h 172.17.71.4 10.167.130.206 <none> <none>
monitoring-grafana-76bd45d446-8v6bb 1/1 Running 0 27m 172.17.71.5 10.167.130.206 <none> <none>
monitoring-influxdb-84f8f76d94-76ffj 1/1 Running 0 27m 172.17.71.7 10.167.130.206 <none> <none>
可以看到kube-dns已经Running了
创建新的pod进行dns的验证看是否正常
cd /home/dns
cat > my-nginx.yaml<<EOF
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: my-nginx #最终会显示到svc中,与集群IP对应关系
spec:
replicas: 2
template:
metadata:
labels:
run: my-nginx
spec:
containers:
- name: my-nginx
image: nginx:1.7.9
ports:
- containerPort: 80
EOF
kubectl create -f my-nginx.yaml
deployment "my-nginx" created
Expose 该Deployment，生成my-nginx 服务
kubectl expose deploy my-nginx
[root@k8s-master01 pod]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 11d
my-nginx ClusterIP 10.0.0.157 <none> 80/TCP 51m
nginx NodePort 10.0.0.116 <none> 88:31961/TCP 10d
tomcat LoadBalancer 10.0.0.16 <pending> 8080:32934/TCP 6d19h
然后创建另外一个Pod，查看/etc/resolv.conf是否包含kubelet配置的–cluster-dns 和–cluster-domain，是否能够将服务my-nginx 解析到上面显示的CLUSTER-IP 10.0.0.157 上
cat > pod-nginx.yaml<<EOF
apiVersion: v1
kind: Pod
metadata:
name: podnginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 80
EOF
kubectl create -f pod-nginx.yaml
pod "podnginx" created
kubectl exec podnginx -i -t /bin/bash #终端交互进入podnginx容器内
查看一下/etc/resolv.conf 看是否是我们创建的dns地址10.0.0.2
[root@node dns]# kubectl exec podnginx -it /bin/bash
root@podnginx:/# cat /etc/resolv.conf
nameserver 10.0.0.2
search default.svc.cluster.local. svc.cluster.local. cluster.local.
options ndots:5
尝试ping一下我们之前创建的my-nginx
root@podnginx:/# ping my-nginx
PING my-nginx.default.svc.cluster.local (10.0.0.157): 48 data bytes #正确解析到了集群IP,ping是不通的,但是可以解析到就OK