Deployment为Pod和ReplicaSets提供声明性更新
示例
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: deploy-myweb
namespace: default
spec:
replicas: 3
selector:
matchLabels:
app: myweb
tier: frontend
template:
metadata:
namespace: default
labels:
app: myweb
tier: frontend
spec:
containers:
- name: container-myweb
image: mycloudedu/myweb:v1
imagePullPolicy: IfNotPresent
将清单提交给kubernetes集群，将创建定义的Deployment及其管理的ReplicaSet与pod
[root@master kubernetes]# kubectl apply -f deploy-myweb.yaml
验证
[root@master kubernetes]# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
deploy-myweb 3/3 3 3 89s[root@master kubernetes]# kubectl get rs
NAME DESIRED CURRENT READY AGE
deploy-myweb-85996f4d65 3 3 3 111s[root@master kubernetes]# kubectl get pod
NAME READY STATUS RESTARTS AGE
deploy-myweb-85996f4d65-4dr58 1/1 Running 0 6s
deploy-myweb-85996f4d65-8vfhl 1/1 Running 0 6s
deploy-myweb-85996f4d65-qsfmj 1/1 Running 0 6s
这里只阐述几个字段：.spec.replicas、.spec.selector、.spec.strategy、.spec.revisionHistoryLimit、.spec.template五个字段。其他字段跟前两篇文章差不多，这里不作阐述。想了解请点击这里。
kubectl explain deployment.spec
replicas <integer> #是指期望值的pod数
selector <Object> -required- #标签选择器，kubernetes根据这个标签查看有几个pod。符不符ReplicaSet合期望值
strategy <Object> #更新pod的策略
template <Object> -required- #创建pod的模板
revisionHistoryLimit <integer> #保存几个历史版本，默认是10个
kubectl explain deployment.spec.selector有两种用法：
matchExpressions <[]Object>
matchLabels <map[string]string>
示例一：键与值的关系
matchExpressions:
- key:KEY
operator： (In, NotIn, Exists and DoesNotExist)
values: [VALUES1,VALUES2,…]
示例二：
matchLabels:
KEY:VALUES
kubectl explain deployment.spec.strategy
rollingUpdate <Object> #当type是RollingUpdate，这个字段才生效
type <string> #类型有两种Recreate与RollingUpdate，默认是RollingUpdate
当type=Recreate时，重新创建pod。当type=RollingUpdata时，重新创建pod是由策略规划。
这里讲解一下type=RollingUpdata。
kubectl explain deployment.spec.strategy.rollingUpdate有两个字段：
maxSurge <string> #最多能多几个pod
maxUnavailable <string> #最多能少几个pod
示例：
rollingUpdate:
maxSurge: <integer>
maxUnavailable: <integer>
这里template不阐述，说几个注意事项：
1.metadata.name这项可以不定义。因为定义了也不会生效。
2.metadata.labels必须含有selector的标签。
3.spec与pod的spec是一样的，这里就不在说明了。需要了解的查看上面文章。
综合示例
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: deploy-myweb
namespace: default
spec:
replicas: 3
selector:
matchLabels:
app: myweb
tier: frontend
strategy:
type: RollingUpdate
rollingUpdate:
maxSurge: 1
maxUnavailable: 1
revisionHistoryLimit: 3
template:
metadata:
namespace: default
labels:
app: myweb
tier: frontend
spec:
containers:
- name: container-myweb
image: mycloudedu/myweb:v1
imagePullPolicy: IfNotPresent
验证
[root@master kubernetes]# kubectl describe deploy deploy-myweb
…
RollingUpdateStrategy: 1 max unavailable, 1 max surge
用打补丁的方式修改策略
[root@master kubernetes]# kubectl patch deployments deploy-myweb -p '{"spec":{"strategy":{"rollingUpdate":{"maxSurge":2,"maxUnavailable":0}}}}'
deployment.apps/deploy-myweb patched
验证
[root@master kubernetes]# kubectl describe deploy deploy-myweb
…
RollingUpdateStrategy: 0 max unavailable, 2 max surge
更新版本，定义更新一个版本暂停。是否跟定义更新策略进行更新
[root@master kubernetes]# kubectl set image deployments deploy-myweb container-myweb=mycloudedu/myweb:v2 && kubectl rollout pause deployment/deploy-myweb
deployment.apps/deploy-myweb image updated
deployment.apps/deploy-myweb paused[root@master ~]# kubectl get pod -w
NAME READY STATUS RESTARTS AGE
deploy-myweb-85996f4d65-4dr58 1/1 Running 0 57m
deploy-myweb-85996f4d65-8vfhl 1/1 Running 0 57m
deploy-myweb-85996f4d65-qsfmj 1/1 Running 0 57m
deploy-myweb-7fff44cfb8-cvbxf 0/1 Pending 0 0s
deploy-myweb-7fff44cfb8-h47lb 0/1 Pending 0 0s
deploy-myweb-7fff44cfb8-cvbxf 0/1 Pending 0 0s
deploy-myweb-7fff44cfb8-h47lb 0/1 Pending 0 0s
deploy-myweb-7fff44cfb8-cvbxf 0/1 ContainerCreating 0 0s
deploy-myweb-7fff44cfb8-h47lb 0/1 ContainerCreating 0 0s
deploy-myweb-7fff44cfb8-h47lb 1/1 Running 0 3s
deploy-myweb-7fff44cfb8-cvbxf 1/1 Running 0 3s原本三个pod还是运行，后面创建一个pod。上面定义的策略是：允许最多多两个，不能减少pod。结论：符合更新策略
取消暂时更新
[root@master kubernetes]# kubectl rollout resume deploy/deploy-myweb
deployment.apps/deploy-myweb resumed
验证
[root@master ~]# kubectl rollout status deploy deploy-myweb
Waiting for deployment "deploy-myweb" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment spec update to be observed...
Waiting for deployment spec update to be observed...
Waiting for deployment "deploy-myweb" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "deploy-myweb" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "deploy-myweb" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "deploy-myweb" rollout to finish: 1 old replicas are pending termination...
deployment "deploy-myweb" successfully rolled out[root@master kubernetes]# kubectl get deploy -o wide
NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR
deploy-myweb 3/3 3 3 65m container-myweb mycloudedu/myweb:v2 app=myweb,tier=frontend
查看历史版本
[root@master kubernetes]# kubectl rollout history deployments deploy-myweb
deployment.apps/deploy-myweb
REVISION CHANGE-CAUSE
1 <none>
2 <none>
回滚历史版本
[root@master kubernetes]# kubectl rollout undo deploy/deploy-myweb --to-revision=1
deployment.apps/deploy-myweb rolled back
验证
[root@master kubernetes]# kubectl get deploy -o wide
NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR
deploy-myweb 3/3 3 3 67m container-myweb mycloudedu/myweb:v1 app=myweb,tier=frontend
