接上一篇通过Rancher部署并扩容Kubernetes集群基础篇一
7. 使用ConfigMap配置redis
https://github.com/kubernetes/kubernetes.github.io/blob/master/docs/user-guide/configmap/redis/redis-config
redis-config
maxmemory 2mb maxmemory-policy allkeys-lru
# kubectl create configmap example-redis-config --from-file=./redis-config
# kubectl get configmap example-redis-config -o yaml apiVersion: v1 data: redis-config: | maxmemory 2mb maxmemory-policy allkeys-lru kind: ConfigMap metadata: creationTimestamp: 2017-07-12T13:27:56Z name: example-redis-config namespace: default resourceVersion: "45707" selfLink: /api/v1/namespaces/default/configmaps/example-redis-config uid: eab522fd-6705-11e7-94da-02672b869d7f
redis-pod.yaml
apiVersion: v1
kind: Pod
metadata:
name: redis
spec:
containers:
- name: redis
p_w_picpath: kubernetes/redis:v1
env:
- name: MASTER
value: "true"
ports:
- containerPort: 6379
resources:
limits:
cpu: "0.1"
volumeMounts:
- mountPath: /redis-master-data
name: data
- mountPath: /redis-master
name: config
volumes:
- name: data
emptyDir: {}
- name: config
configMap:
name: example-redis-config
items:
- key: redis-config
path: redis.conf
# kubectl create -f redis-pod.yaml pod "redis" created
# kubectl exec -it redis redis-cli 127.0.0.1:6379> 127.0.0.1:6379> 127.0.0.1:6379> config get maxmemory 1) "maxmemory" 2) "2097152" 127.0.0.1:6379> config get maxmemory-policy 1) "maxmemory-policy" 2) "allkeys-lru" 127.0.0.1:6379>
8. 使用kubectl命令管理kubernetes对象
# kubectl run nginx --p_w_picpath nginx deployment "nginx" created
或者
# kubectl create deployment nginx --p_w_picpath nginx
使用kubectl create创建一个配置文件中定义的对象
#kubectl create -f nginx.yaml
删除两个配置文件中定义的对象
#kubectl delete -f nginx.yaml -f redis.yaml
更新对象
#kubectl replace -f nginx.yaml
处理configs目录下所有的对象配置文件，创建新的对象或者打补丁现有的对象
#kubectl apply -f configs/
递推处理子目录下的对象配置文件
#kubectl apply -R -f configs/
9. 部署无状态应用
9.1 使用deployment运行一个无状态应用
deployment.yaml
apiVersion: apps/v1beta1 kind: Deployment metadata: name: nginx-deployment spec: replicas: 2 # tells deployment to run 2 pods matching the template template: # create pods using pod definition in this template metadata: # unlike pod-nginx.yaml, the name is not included in the meta data as a unique name is # generated from the deployment name labels: app: nginx spec: containers: - name: nginx p_w_picpath: nginx:1.7.9 ports: - containerPort: 80
kubectl create -f https://k8s.io/docs/tasks/run-application/deployment.yaml
这里需要注意一下，rancher1.6.2部署的是kubernetes 1.5.4
这里的apiVersion要改一下，改成extensions/v1beta1
kubernetes从1.6引入apps/v1beta1.Deployment 替代 extensions/v1beta1.Deployment
显示这个deployment的信息
# kubectl describe deployment nginx-deployment
# kubectl get pods -l app=nginx
更新deployment
deployment-update.yaml
和deployment.yaml除了p_w_picpath不同之外其余的内容相同
p_w_picpath: nginx:1.8
# kubectl apply -f deployment-update.yaml
执行更新后，kubernetes会先创建新的pods，然后再停掉并删除老的pods
# kubectl get pods -l app=nginx # kubectl get pod nginx-deployment-148880595-9l07p -o yaml|grep p_w_picpath: - p_w_picpath: nginx:1.8 p_w_picpath: nginx:1.8
已经更新成功了
通过增加replicas的数量来扩展应用
# cp deployment-update.yaml deployment-scale.yaml
修改deployment-scale.yaml
replicas: 4
# kubectl apply -f deployment-scale.yaml # kubectl get pods -l app=nginx NAME READY STATUS RESTARTS AGE nginx-deployment-148880595-1tb5m 1/1 Running 0 26s nginx-deployment-148880595-9l07p 1/1 Running 0 10m nginx-deployment-148880595-lc113 1/1 Running 0 26s nginx-deployment-148880595-z8l51 1/1 Running 0 10m
删除deployment
# kubectl delete deployment nginx-deployment deployment "nginx-deployment" deleted
创建一个可以复制的应用首选的方式是使用的deployment， deployment会使用ReplicaSet. 在Deployment和ReplicaSet加入到Kubernetes之前，可复制的应用是通过ReplicationController来配置的
9.2 案例： 部署一个以Redis作为存储的PHP留言板
第一步： 启动一个redis master服务
redis-master-deployment.yaml
apiVersion: extensions/v1beta1 kind: Deployment metadata: name: redis-master spec: replicas: 1 template: metadata: labels: app: redis role: master tier: backend spec: containers: - name: master p_w_picpath: gcr.io/google_containers/redis:e2e # or just p_w_picpath: redis resources: requests: cpu: 100m memory: 100Mi ports: - containerPort: 6379
# kubectl create -f redis-master-deployment.yaml
redis-master-service.yaml
apiVersion: v1 kind: Service metadata: name: redis-master labels: app: redis role: master tier: backend spec: ports: - port: 6379 targetPort: 6379 selector: app: redis role: master tier: backend
# kubectl create -f redis-master-service.yaml
# kubectl get services redis-master NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE redis-master 10.43.10.966379/TCP 2m
targetPort是后端容器接收外部流量的端口，port是其他任务pods访问service的端口
kubernetes支持两种主要的模式来发现一个service -- 环境变量和DNS
查看集群DNS
# kubectl --namespace=kube-system get rs -l k8s-app=kube-dns NAME DESIRED CURRENT READY AGE kube-dns-1208858260 1 1 1 1d
# kubectl get pods -n=kube-system -l k8s-app=kube-dns NAME READY STATUS RESTARTS AGE kube-dns-1208858260-c8dbv 4/4 Running 8 1d
第二步： 启动一个redis slave服务
redis-slave.yaml
apiVersion: v1 kind: Service metadata: name: redis-slave labels: app: redis role: slave tier: backend spec: ports: - port: 6379 selector: app: redis role: slave tier: backend --- apiVersion: extensions/v1beta1 kind: Deployment metadata: name: redis-slave spec: replicas: 2 template: metadata: labels: app: redis role: slave tier: backend spec: containers: - name: slave p_w_picpath: gcr.io/google_samples/gb-redisslave:v1 resources: requests: cpu: 100m memory: 100Mi env: - name: GET_HOSTS_FROM value: dns # If your cluster config does not include a dns service, then to # instead access an environment variable to find the master # service's host, comment out the 'value: dns' line above, and # uncomment the line below: # value: env ports: - containerPort: 6379
# kubectl create -f redis-slave.yaml service "redis-slave" created deployment "redis-slave" created
# kubectl get deployments -l app=redis NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE redis-master 1 1 1 1 35m redis-slave 2 2 2 2 5m
# kubectl get services -l app=redis NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE redis-master 10.43.10.966379/TCP 31m redis-slave 10.43.231.209 6379/TCP 6m
# kubectl get pods -l app=redis NAME READY STATUS RESTARTS AGE redis-master-343230949-sc78h 1/1 Running 0 37m redis-slave-132015689-rc1xf 1/1 Running 0 7m redis-slave-132015689-vb0vl 1/1 Running 0 7m
第三步： 启动一个留言板前端
frontend.yaml
apiVersion: v1 kind: Service metadata: name: frontend labels: app: guestbook tier: frontend spec: # if your cluster supports it, uncomment the following to automatically create # an external load-balanced IP for the frontend service. # type: LoadBalancer ports: - port: 80 selector: app: guestbook tier: frontend --- apiVersion: extensions/v1beta1 kind: Deployment metadata: name: frontend spec: replicas: 3 template: metadata: labels: app: guestbook tier: frontend spec: containers: - name: php-redis p_w_picpath: gcr.io/google-samples/gb-frontend:v4 resources: requests: cpu: 100m memory: 100Mi env: - name: GET_HOSTS_FROM value: dns # If your cluster config does not include a dns service, then to # instead access environment variables to find service host # info, comment out the 'value: dns' line above, and uncomment the # line below: # value: env ports: - containerPort: 80
# kubectl create -f frontend.yaml service "frontend" created deployment "frontend" created
# kubectl get services -l tier NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE frontend 10.43.39.18880/TCP 3m redis-master 10.43.10.96 6379/TCP 47m redis-slave 10.43.231.209 6379/TCP 22m
# kubectl get deployments -l tier NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE frontend 3 3 3 3 3m redis-master 1 1 1 1 53m redis-slave 2 2 2 2 22m
# kubectl get pods -l tier NAME READY STATUS RESTARTS AGE frontend-88237173-b7x03 1/1 Running 0 13m frontend-88237173-qg6d7 1/1 Running 0 13m frontend-88237173-zb827 1/1 Running 0 13m redis-master-343230949-sc78h 1/1 Running 0 1h redis-slave-132015689-rc1xf 1/1 Running 0 32m redis-slave-132015689-vb0vl 1/1 Running 0 32m
guestbook.php
'tcp',
'host' => $host,
'port' => 6379,
]);
$client->set($_GET['key'], $_GET['value']);
print('{"message": "Updated"}');
} else {
$host = 'redis-slave';
if (getenv('GET_HOSTS_FROM') == 'env') {
$host = getenv('REDIS_SLAVE_SERVICE_HOST');
}
$client = new Predis\Client([
'scheme' => 'tcp',
'host' => $host,
'port' => 6379,
]);
$value = $client->get($_GET['key']);
print('{"data": "' . $value . '"}');
}
} else {
phpinfo();
} ?>
redis-slave 容器里面有个/run.sh
if [[ ${GET_HOSTS_FROM:-dns} == "env" ]]; then
redis-server --slaveof ${REDIS_MASTER_SERVICE_HOST} 6379
else
redis-server --slaveof redis-master 6379
fi
redis-master通过kube-dns解析
从外部访问这个留言板有两种方式: NodePort和LoadBalancer
更新frontend.yaml
设置 type: NodePort
# kubectl apply -f frontend.yaml
# kubectl get services -l tier NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE frontend 10.43.39.18880:31338/TCP 4h redis-master 10.43.10.96 6379/TCP 5h redis-slave 10.43.231.209 6379/TCP 5h
可以看到frontend对集群外暴露一个31338端口，访问任意一个集群节点
http://172.30.30.217:31338/
更新设置frontend.yaml
设置 type: LoadBalancer
# kubectl apply -f frontend.yaml
使用rancher部署kubernetes，这里设置type为LoadBalancer后，在rancher上可以看到
kubernetes-loadbalancers
默认对外的端口是80，可以自己调整，还可以rancher LB的容器数量
http://172.30.30.217:888/
http://172.30.30.219:888/
10.部署有状态应用
StatefulSets是用于部署有状态应用和分布式系统。部署有状态应用之前需要先部署有动态持久化存储
10.1 StatefulSet基础
使用Ceph集群作为Kubernetes的动态分配持久化存储
10.2 运行一个单实例的有状态应用
10.3 运行一个多实例复制的有状态应用
10.4 部署WordPress和MySQL案例
10.5 部署Cassandra案例
10.6 部署ZooKeeper案例
参考文档：
http://blog.kubernetes.io/2016/10/dynamic-provisioning-and-storage-in-kubernetes.html