k8s系列---dns部署

1：首先创建kube-dns和dnsmasq这两个yaml，然后生成相应的pod、svc等。

2：然后在去创建其他的验证pod和svc

3：验证nslookup解析的是其他pod的svc的name，而不是podname

我的kubernets的版本是1.5的

skydns-rc.yaml   这里的地址记得修改，  - --domain=cluster.local. 或者写成你自己的相应的域名，但是需呀和/etc/kubernets/kubelet  里面的对应起来                                                  -kube-master-url=http://172.16.100.60:8080  是master的物理地址

10.254.0.254 这个ip自己定义的定义dns svc的地址，但是得保证在apiserver配置文件里的范围内

其他node节点是不是也要修改kubelet配置文件？我没测试，但也直接改了kubelet配置文件

[root@centos-master dns]# tail -n 1 /etc/kubernetes/kubelet
KUBELET_ARGS="--cluster-dns=10.254.0.254 --cluster-domain=cluster.local"

　　

上面定义的dnsip要在下面这个范围内

[root@centos-master dns]# tail -n 8 /etc/kubernetes/apiserver
# Address range to use for services
KUBE_SERVICE_ADDRESSES="--service-cluster-ip-range=10.254.0.0/16"

# default admission control policies
KUBE_ADMISSION_CONTROL="--admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ResourceQuota"

# Add your own!
KUBE_API_ARGS=""

　　

[root@centos-master dns]# cat skydns-rc.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: kube-dns
  namespace: kube-system
  labels:
    k8s-app: kube-dns
    kubernetes.io/cluster-service: "true"
spec:
  #指定副本数
  replicas: 1
  # 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: ''
        scheduler.alpha.kubernetes.io/tolerations: '[{"key":"CriticalAddonsOnly", "operator":"Exists"}]'
    spec:
      containers:
      - name: kubedns
        image: docker.io/ist0ne/kubedns-amd64:latest
        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: /healthz-kubedns
            port: 8080
            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:
        #指定一级域名
        - --domain=cluster.local.
        - --dns-port=10053
        - --config-map=kube-dns
        #增加kube-master-url,指向k8s_master地址
        - --kube-master-url=http://172.16.100.60:8080
        # This should be set to v=2 only after the new image (cut from 1.5) has
        # been released, otherwise we will flood the logs.
        - --v=0
        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
      - name: dnsmasq
        image: docker.io/ist0ne/k8s-dns-dnsmasq-amd64:latest
        livenessProbe:
          httpGet:
            path: /healthz-dnsmasq
            port: 8080
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        args:
        - --cache-size=1000
        - --no-resolv
        - --server=127.0.0.1#10053
        #注释掉
        #- --log-facility=-
        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: 10Mi
      - name: dnsmasq-metrics
        image: docker.io/ist0ne/dnsmasq-metrics-amd64:latest
        livenessProbe:
          httpGet:
            path: /metrics
            port: 10054
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        args:
        - --v=2
        - --logtostderr
        ports:
        - containerPort: 10054
          name: metrics
          protocol: TCP
        resources:
          requests:
            memory: 10Mi
      - name: healthz
        image: docker.io/ist0ne/exechealthz-amd64:latest
        resources:
          limits:
            memory: 50Mi
          requests:
            cpu: 10m
            # Note that this container shouldn't really need 50Mi of memory. The
            # limits are set higher than expected pending investigation on #29688.
            # The extra memory was stolen from the kubedns container to keep the
            # net memory requested by the pod constant.
            memory: 50Mi
        args:
        - --cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1 >/dev/null
        - --url=/healthz-dnsmasq
        - --cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1:10053 >/dev/null
        - --url=/healthz-kubedns
        - --port=8080
        - --quiet
        ports:
        - containerPort: 8080
          protocol: TCP
      dnsPolicy: Default  # Don't use cluster DNS.

　　

[root@centos-master dns]# cat skydns-svc.yaml
apiVersion: v1
kind: Service
metadata:
  name: kube-dns
  namespace: kube-system
  labels:
    k8s-app: kube-dns
    kubernetes.io/cluster-service: "true"
    kubernetes.io/name: "KubeDNS"
spec:
  selector:
    k8s-app: kube-dns
  clusterIP: 10.254.0.254
  ports:
  - name: dns
    port: 53
    protocol: UDP
  - name: dns-tcp
    port: 53
    protocol: TCP

　

[root@centos-master dns]# kubectl create -f skydns-rc.yaml
[root@centos-master dns]# kubectl create -f skydns-svc.yaml

　　

创建完上面两个yaml的pod和svc，然后就可以创建其他测试的pod了

比如创建一个mysql的创建一个buxybox验证的

[root@centos-master yaml]# cat busybox.yaml
apiVersion: v1
kind: Pod
metadata:
  name: busybox
spec:
  containers:
  - image: busybox
    command:
      - sleep
      - "3600"
    name: busybox

[root@centos-master yaml]# cat mysql-rc.yaml
apiVersion: v1
kind: ReplicationController
metadata:
  name: mysql
spec:
  replicas: 3
  selector:
    app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:5.5
        ports:
        - containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "123456"

[root@centos-master yaml]# cat mysql-svc.yaml
apiVersion: v1
kind: Service
metadata:
  name: mysql
spec:
  ports:
    - port: 3306
  selector:
    app: mysql

　　

[root@centos-master yaml]# kubectl create -f busybox.yaml
[root@centos-master yaml]# kubectl create -f mysql-rc.yaml
[root@centos-master yaml]# kubectl create -f mysql-svc.yaml

　　

启动busybox查看/etc/resolv.conf   ，不出意外的话以后所有新建的pod resolv.conf里面都将生成一条记录，注意解析的是svc的名字

[root@centos-master yaml]# kubectl exec -it busybox  -- sh
/ # cat /etc/resolv.conf
search default.svc.cluster.local svc.cluster.local cluster.local
nameserver 10.254.0.254
nameserver 202.106.0.20
options ndots:5
/ # nslookup mysql
Server:    10.254.0.254
Address 1: 10.254.0.254 kube-dns.kube-system.svc.cluster.local

Name:      mysql
Address 1: 10.254.130.59 mysql.default.svc.cluster.local
/ # nslookup kubernetes
Server:    10.254.0.254
Address 1: 10.254.0.254 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes
Address 1: 10.254.0.1 kubernetes.default.svc.cluster.local

　　

[root@centos-master yaml]# kubectl get svc  | grep -E "mysql|kubernetes"
kubernetes     10.254.0.1       <none>        443/TCP        6d
mysql          10.254.130.59    <none>        3306/TCP       17m

　　

以上，dns全部完成。