Kubernetes cluster configuration DNS Service

On the basis of the previous article, this article will introduce kubernetes colony Configuration in environment dns service , stay k8s colony in ,pod The life cycle of life is short ,pod After restart ip The address will change , This is unacceptable for applications , To solve this problem ,K8S colony Cleverly introduced dns Service to realize service discovery , stay k8s In the cluster dns A total of 4 A component , The division of labor of each component is as follows ： etcd：DNS Storage kube2sky： take Kubernetes Master Medium service（ service ） Sign up to etcd. skyDNS： Provide DNS Domain name resolution service . healthz： Provide right skydns Health check of service .

One 、 Download relevant image files , And incorporated into the local warehouse for unified management

# docker pull docker.io/elcolio/etcd # docker pull docker.io/port/kubernetes-kube2sky # docker pull docker.io/skynetservices/skydns # docker pull docker.io/wu1boy/healthz

# docker tag docker.io/elcolio/etcd registry.fjhb.cn/etcd # docker tag docker.io/port/kubernetes-kube2sky registry.fjhb.cn/kubernetes-kube2sky # docker tag docker.io/skynetservices/skydns  registry.fjhb.cn/skydns # docker tag docker.io/wu1boy/healthz registry.fjhb.cn/healthz

# docker push registry.fjhb.cn/etcd # docker push registry.fjhb.cn/kubernetes-kube2sky # docker push registry.fjhb.cn/skydns # docker push registry.fjhb.cn/healthz # docker images |grep fjhb

Two 、 adopt rc File creation pod One of them pod Contains 4 A component , A component runs in a docker In the container

# cat skydns-rc.yaml apiVersion: v1 kind: ReplicationController metadata:   name: kube-dns   namespace: default   labels:     k8s-app: kube-dns     version: v12     kubernetes.io/cluster-service: "true" spec:   replicas: 1   selector:     k8s-app: kube-dns     version: v12   template:     metadata:       labels:         k8s-app: kube-dns         version: v12         kubernetes.io/cluster-service: "true"     spec:       containers:       - name: etcd         image: registry.fjhb.cn/etcd         resources:           limits:             cpu: 100m             memory: 50Mi           requests:             cpu: 100m             memory: 50Mi         command:         - /bin/etcd         - --data-dir         - /tmp/data         - --listen-client-urls         - http://127.0.0.1:2379,http://127.0.0.1:4001         - --advertise-client-urls         - http://127.0.0.1:2379,http://127.0.0.1:4001         - --initial-cluster-token         - skydns-etcd         volumeMounts:         - name: etcd-storage           mountPath: /tmp/data       - name: kube2sky         image: registry.fjhb.cn/kubernetes-kube2sky         resources:           limits:             cpu: 100m             memory: 50Mi           requests:             cpu: 100m             memory: 50Mi         args:         - -kube_master_url=http://192.168.115.5:8080         - -domain=cluster.local       - name: skydns         image: registry.fjhb.cn/skydns         resources:           limits:             cpu: 100m             memory: 50Mi           requests:             cpu: 100m             memory: 50Mi         args:         - -machines=http://127.0.0.1:4001         - -addr=0.0.0.0:53         - -ns-rotate=false         - -domain=cluster.local         ports:         - containerPort: 53           name: dns           protocol: UDP         - containerPort: 53           name: dns-tcp           protocol: TCP       - name: healthz         image: registry.fjhb.cn/healthz         resources:           limits:             cpu: 10m             memory: 20Mi           requests:             cpu: 10m             memory: 20Mi         args:         - -cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1 >/dev/null         - -port=8080         ports:         - containerPort: 8080           protocol: TCP       volumes:       - name: etcd-storage         emptyDir: {}       dnsPolicy: Default

3、 ... and 、 adopt srv File creation service

# cat skydns-svc.yaml  apiVersion: v1 kind: Service metadata:   name: kube-dns   namespace: default   labels:     k8s-app: kube-dns     kubernetes.io/cluster-service: "true"     kubernetes.io/name: "KubeDNS" spec:   selector:     k8s-app: kube-dns   clusterIP: 10.254.16.254   ports:   - name: dns     port: 53     protocol: UDP   - name: dns-tcp     port: 53     protocol: TCP# kubectl create -f skydns-rc.yaml # kubectl create -f skydns-svc.yaml # kubectl get rc # kubectl get pod # kubectl get svc

# kubectl describe svc kube-dns

# kubectl describe rc kube-dns

# kubectl describe pod kube-dns-9fllp Name:          kube-dns-9fllp Namespace:      default Node:          192.168.115.6/192.168.115.6 Start Time:    Tue, 23 Jan 2018 10:55:19 -0500 Labels:        k8s-app=kube-dns                 kubernetes.io/cluster-service=true                 version=v12 Status:        Running IP:            172.16.37.5 Controllers:    ReplicationController/kube-dns Containers:   etcd:     Container ID:      docker://62ad76bfaca1797c5f43b0e9eebc04074169fce4cc15ef3ffc4cd19ffa9c8c19     Image:              registry.fjhb.cn/etcd     Image ID:          docker-pullable://docker.io/elcolio/[email protected]:3b4dcd35a7eefea9ce2970c81dcdf0d0801a778d117735ee1d883222de8bbd9f     Port:     Command:       /bin/etcd       --data-dir       /tmp/data       --listen-client-urls       http://127.0.0.1:2379,http://127.0.0.1:4001       --advertise-client-urls       http://127.0.0.1:2379,http://127.0.0.1:4001       --initial-cluster-token       skydns-etcd     Limits:       cpu:      100m       memory:  50Mi     Requests:       cpu:              100m       memory:          50Mi     State:              Running       Started:          Tue, 23 Jan 2018 10:55:23 -0500     Ready:              True     Restart Count:      0     Volume Mounts:       /tmp/data from etcd-storage (rw)       /var/run/secrets/kubernetes.io/serviceaccount from default-token-6pddn (ro)     Environment Variables:      <none>   kube2sky:     Container ID:      docker://6b0bc6e8dce83e3eee5c7e654fbaca693730623fb7936a1fd9d73de1a1dd8152     Image:              registry.fjhb.cn/kubernetes-kube2sky     Image ID:          docker-pullable://docker.io/port/[email protected]:0230d3fbb0aeb4ddcf903811441cf2911769dbe317a55187f58ca84c95107ff5     Port:     Args:       -kube_master_url=http://192.168.115.5:8080       -domain=cluster.local     Limits:       cpu:      100m       memory:  50Mi     Requests:       cpu:              100m       memory:          50Mi     State:              Running       Started:          Tue, 23 Jan 2018 10:55:25 -0500     Ready:              True     Restart Count:      0     Volume Mounts:       /var/run/secrets/kubernetes.io/serviceaccount from default-token-6pddn (ro)     Environment Variables:      <none>   skydns:     Container ID:      docker://ebc2aaaa54e2f922e370e454ec537665d813c69d37a21e3afd908e6dad056627     Image:              registry.fjhb.cn/skydns     Image ID:          docker-pullable://docker.io/skynetservices/[email protected]:6f8a9cff0b946574bb59804016d3aacebc637581bace452db6a7515fa2df79ee     Ports:              53/UDP, 53/TCP     Args:       -machines=http://127.0.0.1:4001       -addr=0.0.0.0:53       -ns-rotate=false       -domain=cluster.local     Limits:       cpu:      100m       memory:  50Mi     Requests:       cpu:              100m       memory:          50Mi     State:              Running       Started:          Tue, 23 Jan 2018 10:55:27 -0500     Ready:              True     Restart Count:      0     Volume Mounts:       /var/run/secrets/kubernetes.io/serviceaccount from default-token-6pddn (ro)     Environment Variables:      <none>   healthz:     Container ID:      docker://f1de1189fa6b51281d414d7a739b86494b04c8271dc6bb5f20c51fac15ec9601     Image:              registry.fjhb.cn/healthz     Image ID:          docker-pullable://docker.io/wu1boy/[email protected]:d6690c0a8cc4f810a5e691b6a9b8b035192cb967cb10e91c74824bb4c8eea796     Port:              8080/TCP     Args:       -cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1 >/dev/null       -port=8080     Limits:       cpu:      10m       memory:  20Mi     Requests:       cpu:              10m       memory:          20Mi     State:              Running       Started:          Tue, 23 Jan 2018 10:55:29 -0500     Ready:              True     Restart Count:      0     Volume Mounts:       /var/run/secrets/kubernetes.io/serviceaccount from default-token-6pddn (ro)     Environment Variables:      <none> Conditions:   Type          Status   Initialized  True   Ready        True   PodScheduled  True Volumes:   etcd-storage:     Type:      EmptyDir (a temporary directory that shares a pod's lifetime)     Medium:   default-token-6pddn:     Type:      Secret (a volume populated by a Secret)     SecretName: default-token-6pddn QoS Class:      Guaranteed Tolerations:    <none> Events:   FirstSeen    LastSeen        Count  From                    SubObjectPath                  Type            Reason        Message   ---------    --------        -----  ----                    -------------                  --------        ------        -------   7m            7m              1      {default-scheduler }                                    Normal          Scheduled    Successfully assigned kube-dns-9fllp to 192.168.115.6   7m            7m              1      {kubelet 192.168.115.6} spec.containers{etcd}          Normal          Pulling      pulling image "registry.fjhb.cn/etcd"   7m            7m              1      {kubelet 192.168.115.6} spec.containers{etcd}          Normal          Pulled        Successfully pulled image "registry.fjhb.cn/etcd"   7m            7m              1      {kubelet 192.168.115.6} spec.containers{etcd}          Normal          Created      Created container with docker id 62ad76bfaca1; Security:[seccomp=unconfined]   7m            7m              1      {kubelet 192.168.115.6} spec.containers{kube2sky}      Normal          Pulled        Successfully pulled image "registry.fjhb.cn/kubernetes-kube2sky"   7m            7m              1      {kubelet 192.168.115.6} spec.containers{etcd}          Normal          Started      Started container with docker id 62ad76bfaca1   7m            7m              1      {kubelet 192.168.115.6} spec.containers{kube2sky}      Normal          Pulling      pulling image "registry.fjhb.cn/kubernetes-kube2sky"   7m            7m              1      {kubelet 192.168.115.6} spec.containers{kube2sky}      Normal          Created      Created container with docker id 6b0bc6e8dce8; Security:[seccomp=unconfined]   7m            7m              1      {kubelet 192.168.115.6} spec.containers{skydns}        Normal          Pulled        Successfully pulled image "registry.fjhb.cn/skydns"   7m            7m              1      {kubelet 192.168.115.6} spec.containers{skydns}        Normal          Pulling      pulling image "registry.fjhb.cn/skydns"   7m            7m              1      {kubelet 192.168.115.6} spec.containers{kube2sky}      Normal          Started      Started container with docker id 6b0bc6e8dce8   7m            7m              1      {kubelet 192.168.115.6} spec.containers{skydns}        Normal          Created      Created container with docker id ebc2aaaa54e2; Security:[seccomp=unconfined]   7m            7m              1      {kubelet 192.168.115.6} spec.containers{skydns}        Normal          Started      Started container with docker id ebc2aaaa54e2   7m            7m              1      {kubelet 192.168.115.6} spec.containers{healthz}        Normal          Pulling      pulling image "registry.fjhb.cn/healthz"   7m            7m              1      {kubelet 192.168.115.6} spec.containers{healthz}        Normal          Pulled        Successfully pulled image "registry.fjhb.cn/healthz"   7m            7m              1      {kubelet 192.168.115.6} spec.containers{healthz}        Normal          Created      Created container with docker id f1de1189fa6b; Security:[seccomp=unconfined]   7m            7m              1      {kubelet 192.168.115.6} spec.containers{healthz}        Normal          Started      Started container with docker id f1de1189fa6b

Four 、 modify kubelet Configure the file and restart the service

Be careful :

--cluster-dns Parameters should be the same as before svc In the document clusterIP Parameters are consistent

--cluster-domain Parameters should be the same as before rc In the document -domain Parameters are consistent

All of the kubelet Nodes need to be modified

# grep 'KUBELET_ADDRESS' /etc/kubernetes/kubelet    KUBELET_ADDRESS="--address=192.168.115.5 --cluster-dns=10.254.16.254 --cluster-domain=cluster.local" # systemctl restart kubelet

5、 ... and 、 Run one busybox and curl To test

# cat busybox.yaml apiVersion: v1 kind: Pod metadata:   name: busybox spec:   containers:   - name: busybox     image: docker.io/busybox     command:     - sleep - "3600"# cat curl.yaml apiVersion: v1 kind: Pod metadata:   name: curl spec:   containers:   - name: curl     image: docker.io/webwurst/curl-utils     command:     - sleep - "3600"# kubectl create -f busybox.yaml # kubectl create -f curl.yaml

adopt busybox Container pair kubernetes Of service To analyze , Find out service It is automatically parsed into the corresponding cluster ip Address , It's not 172.16 The network segment docker Address

# kubectl get svc # kubectl exec busybox -- nslookup frontend # kubectl exec busybox -- nslookup Redis-master # kubectl exec busybox -- nslookup redis-slave

adopt curl The container accesses the previously created php Message board

# kubectl exec curl -- curl frontend