基于Kubernetess集群部署完整示例——Guestbook
本文依赖环境：Centos7部署Kubernetes集群、基于Kubernetes集群部署skyDNS服务该示例中，我们将创建一个redis-master、两个redis-slave、三个frontend。其中，slave会实时备份master中数据，frontend会向master中写数据，之后会从slave中读取数据。所有系统间的调用（例如slave找master同步数据；frontend找master写数据；frontend找slave读数据等），采用的是dns方式实现。
1、准备工作
1.1镜像准备
本示例中依赖以下几个镜像，请提前准备好：
docker.io/redis:latest 1a8a9ee54eb7
registry.access.redhat.com/rhel7/pod-infrastructure:latest 34d3450d733b
gcr.io/google_samples/gb-frontend:v3 c038466384ab
gcr.io/google_samples/gb-redisslave:v1 5f026ddffa27
1.2环境准备
需要一套kubernetes运行环境，及Cluster DNS，如下：
# kubectl cluster-info
Kubernetes master is running at http://localhost:8080
KubeDNS is running at http://localhost:8080/api/v1/proxy/namespaces/kube-system/services/kube-dns
kubernetes-dashboard is running at http://localhost:8080/api/v1/proxy/namespaces/kube-system/services/kubernetes-dashboard
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
# kubectl get componentstatus
NAME STATUS MESSAGE ERROR
scheduler Healthy ok
controller-manager Healthy ok
etcd-0 Healthy {"health": "true"}
# kubectl get nodes
NAME STATUS AGE
k8s-node-1 Ready 7d
k8s-node-2 Ready 7d
#kubectl get deployment --all-namespaces
NAMESPACE NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
kube-system kube-dns 1 1 1 1 5d
kube-system kubernetes-dashboard-latest 1 1 1 1 6d
#
2、运行redis-master
2.1yaml文件
1）redis-master-controller.yaml
apiVersion: v1
kind: ReplicationController
metadata:
name: redis-master
labels:
name: redis-master
spec:
replicas: 1
selector:
name: redis-master
template:
metadata:
labels:
name: redis-master
spec:
containers:
- name: master
image: redis
ports:
- containerPort: 6379
2）redis-master-service.yaml
apiVersion: v1
kind: Service
metadata:
name: redis-master
labels:
name: redis-master
spec:
ports:
# the port that this service should serve on
- port: 6379
targetPort: 6379
selector:
name: redis-master
2.2创建rc及service
Master上执行：
# kubectl create -f redis-master-controller.yaml
replicationcontroller " redis-master" created
# kubectl create -f redis-master-service.yaml
service " redis-master" created
# kubectl get rc
NAME DESIRED CURRENT READY AGE
redis-master 1 1 1 1d
# kubectl get pod
NAME READY STATUS RESTARTS AGE
redis-master-5wyku 1/1 Running 0 1d
3、运行redis-slave
3.1yaml文件
1）redis-slave-controller.yaml
apiVersion: v1
kind: ReplicationController
metadata:
name: redis-slave
labels:
name: redis-slave
spec:
replicas: 2
selector:
name: redis-slave
template:
metadata:
labels:
name: redis-slave
spec:
containers:
- name: worker
image: gcr.io/google_samples/gb-redisslave:v1
env:
- name: GET_HOSTS_FROM
value: dns
ports:
- containerPort: 6379
2）redis-slave-service.yaml
apiVersion: v1
kind: Service
metadata:
name: redis-slave
labels:
name: redis-slave
spec:
ports:
- port: 6379
selector:
name: redis-slave
3.2创建rc及service
Master上执行：
# kubectl create -f redis-slave-controller.yaml
replicationcontroller "redis-slave" created
# kubectl create -f redis-slave-service.yaml
service "redis-slave" created
# kubectl get rc
NAME DESIRED CURRENT READY AGE
redis-master 1 1 1 1d
redis-slave 2 2 2 44m
# kubectl get pod
NAME READY STATUS RESTARTS AGE
redis-master-5wyku 1/1 Running 0 1d
redis-slave-7h295 1/1 Running 0 44m
redis-slave-r355y 1/1 Running 0 44m
4、运行frontend
4.1yaml文件
1）frontend-controller.yaml
apiVersion: v1
kind: ReplicationController
metadata:
name: frontend
labels:
name: frontend
spec:
replicas: 3
selector:
name: frontend
template:
metadata:
labels:
name: frontend
spec:
containers:
- name: frontend
image: gcr.io/google_samples/gb-frontend:v3
env:
- name: GET_HOSTS_FROM
value: dns
ports:
- containerPort: 80
2）frontend-service.yaml
apiVersion: v1
kind: Service
metadata:
name: frontend
labels:
name: fronted
spec:
type: NodePort
ports:
- port: 80
nodePort: 30001
selector:
name: frontend
4.2创建rc及service
Master上执行：
# kubectl create -f frontend-controller.yaml
replicationcontroller "frontend" created
# kubectl create -f frontend-service.yaml
service "frontend" created
# kubectl get rc
NAME DESIRED CURRENT READY AGE
frontend 3 3 3 28m
redis-master 1 1 1 1d
redis-slave 2 2 2 44m
# kubectl get pod
NAME READY STATUS RESTARTS AGE
frontend-ax654 1/1 Running 0 29m
frontend-k8caj 1/1 Running 0 29m
frontend-x6bhl 1/1 Running 0 29m
redis-master-5wyku 1/1 Running 0 1d
redis-slave-7h295 1/1 Running 0 44m
redis-slave-r355y 1/1 Running 0 44m
# kubectl get service
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
frontend 10.254.93.91 <nodes> 80/TCP 47m
kubernetes 10.254.0.1 <none> 443/TCP 7d
redis-master 10.254.132.210 <none> 6379/TCP 1d
redis-slave 10.254.104.23 <none> 6379/TCP 1h
4.3页面验证
至此，Guestbook已经运行在了kubernetes中了，但是外部是无法通过通过frontend-service的IP10.0.93.91这个IP来进行访问的。Service的虚拟IP是kubernetes虚拟出来的内部网络，在外部网络中是无法寻址到的，这时候就需要增加一层外网到内网的网络转发。我们的示例中采用的是NodePort的方式实现的，之前在创建frontend-service时设置了nodePort: 30001，即kubernetes将会在每个Node上设置端口，成为NodePort，通过NodePort端口可以访问到真正的服务。
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