Pet Set 和init Container
Pet Set/StatefulSet
有状态的pod，对于存储类的服务如mysql，不能按照无状态来处理，需要有状态的pod。 在1.5版本之后PetSet被改名为StatefulSet。
StatefulSet
apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
app: nginx
spec:
ports:
- port: 80
name: web
clusterIP: None
selector:
app: nginx
---
apiVersion: apps/v1beta1 # 1.9里apps/v1可用，之前的版本可能还是要apps/v1beta1
kind: StatefulSet
metadata:
name: web
spec:
selector:
matchLabels:
app: nginx # has to match .spec.template.metadata.labels
serviceName: "nginx"
replicas: 3 # by default is 1
template:
metadata:
labels:
app: nginx # has to match .spec.selector.matchLabels
spec:
terminationGracePeriodSeconds: 10
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
name: web
volumeMounts:
- name: www
mountPath: /usr/share/nginx/html
volumeClaimTemplates:
- metadata:
name: www
annotation:
volume.alpha.kubernetes.io/storge-class: anything
spec:
accessModes: [ "ReadWriteOnce" ]
#storageClassName: my-storage-class 1.9中直接作为属性
resources:
requests:
storage: 1Gi
这里volumeClaimTemplate是向PV申请资源的，需要管理员创建好PV，PV的部分就不展开讲了，可以参考以及这。statefulset可以创建多个副本，创建的时候podname-xxx中xxx不再是hash而是按照顺序从0自增，也是按照这个顺序创建，销毁则是反序销毁。如上设置的StatefulSet的name是web，就会创建pod为web-0,web-1，web-2这样三个pod。
InitContainer
在pod中容器创建应用启动之前创建的容器，主要用来做一些预先的修改
apiVersion: v1
kind: Pod
metadata:
name: myapp-pod
labels:
app: myapp
annotations:
pod.beta.kubernetes.io/init-containers: '[
{
"name": "init-myservice",
"image": "busybox",
"command": ["sh", "-c", "until nslookup myservice; do echo waiting for myservice; sleep 2; done;"]
},
{
"name": "init-mydb",
"image": "busybox",
"command": ["sh", "-c", "until nslookup mydb; do echo waiting for mydb; sleep 2; done;"]
}
]'
spec:
containers:
- name: myapp-container
image: busybox
command: ['sh', '-c', 'echo The app is running! && sleep 3600']
也常用在需要预先下载文件如运行wget指令下载到volumeMounts然后通过emptyDir: 类型挂载到后续的Pod中。