通过Rancher部署并扩容Kubernetes集群基础篇二

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
image: 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 --image nginx
deployment "nginx" created

或者

# kubectl create deployment nginx --image 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
image: nginx:1.7.9
ports:
- containerPort: 80

kubectl create -f https://k8s.io/docs/tasks/run-application/deployment.yaml[/code] 
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image不同之外其余的内容相同
image: 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 image:
- image: nginx:1.8
image: 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
image: gcr.io/google_containers/redis:e2e  # or just image: 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   10.43.10.96   <none>        6379/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
image: 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   10.43.10.96     <none>        6379/TCP   31m
redis-slave    10.43.231.209   <none>        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
image: 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       10.43.39.188    <none>        80/TCP     3m
redis-master   10.43.10.96     <none>        6379/TCP   47m
redis-slave    10.43.231.209   <none>        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

<?php

error_reporting(E_ALL);
ini_set('display_errors', 1);

require 'Predis/Autoloader.php';

Predis\Autoloader::register();

if (isset($_GET['cmd']) === true) {
$host = 'redis-master';
if (getenv('GET_HOSTS_FROM') == 'env') {
$host = getenv('REDIS_MASTER_SERVICE_HOST');
}
header('Content-Type: application/json');
if ($_GET['cmd'] == 'set') {
$client = new Predis\Client([
'scheme' => '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       10.43.39.188    <nodes>       80:31338/TCP   4h
redis-master   10.43.10.96     <none>        6379/TCP       5h
redis-slave    10.43.231.209   <none>        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