Deployment 提供了声明式的pods和Replica配置。只需要描述一个部署对象，即可根据该描述参建或者更资源。
使用场景：
- 参建副本集和 Pods
- 检查部署状态
- 更新升级Pods
- 回滚到历史版本
- 暂停或恢复部署
创建Deployment
新建文件nginx-deployment.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: nginx-deployment
spec:
replicas: 2
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 80
参建deployment
kubectl create -f nginx-deployment.yml --record
--record可以不加，但是添加这个可以将当前命令记录在正在创建或更新的资源的注释中。 有助于查看在每个部署版本中执行的命令。
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deployment 2 2 2 2 4m
查看部署的pods和RS
kubectl get rs
kubectl get pods
$ kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
nginx-deployment-4087004473-2wphk 1/1 Running 0 12m app=nginx,pod-template-hash=4087004473
nginx-deployment-4087004473-cx2tv 1/1 Running 0 12m app=nginx,pod-template-hash=4087004473
app=nignx 标签 ； hash值4087004473 RC name =
<the name of the Deployment>-<hash value of the pod template>注意：要设置和合适的选择器（app=nginx）和spec模板，不要和其他deployment、rs，Replication Controllers等重叠。
Deployment状态
在对一个 Deployment升级时，想确认是否成功，最简单的方式是通过kubectl rollout status查看，如：
kubectl rollout status deployment/nginx-deployment
kubectl rollout status -f nginx-deployment
比如副本从2个升级到4个时：
$ kubectl rollout status deployment/nginx-deployment
Waiting for deployment spec update to be observed...
Waiting for rollout to finish: 2 out of 4 new replicas have been updated...
Waiting for rollout to finish: 2 out of 4 new replicas have been updated...
Waiting for rollout to finish: 2 of 4 updated replicas are available...
Waiting for rollout to finish: 3 of 4 updated replicas are available...
deployment "nginx-deployment" successfully rolled out
Deployment 更新
变更部署对象时，可以直接更改yml部署文件更改，让后使用apply更新。也可以直接使用命令指定更新，如使用其他版本的nginx镜像。
$ kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1
deployment "nginx-deployment" image updated
要查看deployment的历史更新记录，可以通过describe:
kubectl describe deployments
Name: nginx-deployment
Namespace: default
CreationTimestamp: Mon, 20 Mar 2017 22:12:37 +0800
Labels: app=nginx
Selector: app=nginx
Replicas: 4 updated | 4 total | 4 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 1 max unavailable, 1 max surge
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
OldReplicaSets: <none>
NewReplicaSet: nginx-deployment-4087004473 (4/4 replicas created)
Events:
FirstSeen LastSeen Count From SubObjectPath Type Reason Message
--------- -------- ----- ---- ------------- -------- ------ -------
50m 50m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-4087004473 to 2
25m 25m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-4087004473 to 333
21m 21m 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set nginx-deployment-4087004473 to 3
10m 10m 1 {deployment-controller } Normal ScalingReplicaSet Scaled down replica set nginx-deployment-4087004473 to 2
10m 10m 1 {deployment-controller } Normal ScalingReplicaSet Scaled up replica set nginx-deployment-4087004473 to 4
上例可以看到replica set的扩容和收缩记录。
Deployment回退
如果某个部署版本不稳定，可以回退到历史版本。默认情况下，将保存所有历史版本，也可以通过设置.spec.revisionHistoryLimit作限制，如果值为0，表示清除历史版本记录。需要注意的是，只有在.spec.template发生改变时(如：更新标签或镜像)，才会有版本记录。对于扩容等非template改变将不会有版本记录。
比如，我把nignx从1.7.9升级到latest
$ kubectl set image deployment/nginx-deployment nginx=nginx:latest
$ kubectl rollout history -f nginx-deployment.yml
deployments "nginx-deployment"
REVISION CHANGE-CAUSE
1 kubectl apply -f nginx.yml --record
2 kubectl set image deployment/nginx-deployment nginx=nginx:latest
知道版本后，我们可以通过undo回退到上一个版本或者指定版本。
kubectl rollout undo deployment/nginx-deployment
kubectl rollout undo deployment/nginx-deployment --to-revision=2
Deployment扩缩容
直接修改yml部署文件中的replicas或者使用scale命令都能实现扩缩容的效果。
kubectl scale deployment nginx-deployment --replicas 3
在集群环境中，可以设置自动伸缩。
$ kubectl autoscale deployment nginx-deployment --min=10 --max=15 --cpu-percent=80
deployment "nginx-deployment" autoscaled
min: 最小副本数 max：最大副本数 –cpu-percent=80
Deployment 暂停和恢复
可以通过控制deployment的执行过程实现“金丝雀发布”，
$ kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1; kubectl rollout pause deployment/nginx-deployment
deployment "nginx-deployment" image updated
deployment "nginx-deployment" paused
同事有两个版本在跑
kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-deployment-2273492681 2 2 2 42m
nginx-deployment-4087004473 2 2 2 12h
nginx-deployment-4182293765 0 0 0 1h
$ kubectl rollout status deployment/nginx-deployment
# 恢复deploy
$ kubectl rollout resume deployment/nginx-deployment
Deployment 配置
查看正则运行的版本配置可以通过以下命令：
kubectl get deployment nginx-deployment -o yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "5"
kubectl.kubernetes.io/last-applied-configuration: '{"kind":"Deployment","apiVersion":"extensions/v1beta1","metadata":{"name":"nginx-deployment","creationTimestamp":null},"spec":{"replicas":3,"template":{"metadata":{"creationTimestamp":null,"labels":{"app":"nginx"}},"spec":{"containers":[{"name":"nginx","image":"nginx:1.7.9","ports":[{"containerPort":80}],"resources":{}}]}},"strategy":{},"revisionHistoryLimit":5},"status":{}}'
kubernetes.io/change-cause: kubectl apply -f nginx.yml --record
creationTimestamp: 2017-03-21T03:36:49Z
generation: 13
labels:
app: nginx
name: nginx-deployment
namespace: default
resourceVersion: "96882"
selfLink: /apis/extensions/v1beta1/namespaces/default/deployments/nginx-deployment
uid: 9dfe0a3f-0de7-11e7-a5ac-080027f0adcd
spec:
replicas: 3
revisionHistoryLimit: 5
selector:
matchLabels:
app: nginx
strategy:
rollingUpdate:
maxSurge: 1
maxUnavailable: 1
type: RollingUpdate
template:
metadata:
creationTimestamp: null
labels:
app: nginx
spec:
containers:
- image: nginx:1.7.9
imagePullPolicy: IfNotPresent
name: nginx
ports:
- containerPort: 80
protocol: TCP
resources: {}
terminationMessagePath: /dev/termination-log
dnsPolicy: ClusterFirst
restartPolicy: Always
securityContext: {}
terminationGracePeriodSeconds: 30
status:
availableReplicas: 3
conditions:
- lastTransitionTime: 2017-03-21T03:40:01Z
lastUpdateTime: 2017-03-21T03:40:01Z
message: Deployment has minimum availability.
reason: MinimumReplicasAvailable
status: "True"
type: Available
observedGeneration: 13
replicas: 3
updatedReplicas: 3
通过此配置，我们也可以参考调整yml配置然后apply -f。
Pod Template .spec.template
- metadata: 设置labels等。
.spec.template.metadata.labels和.spec.selector相等，才会被Replication Controller管理。 - restartPolicy: Always默认
- spec.containers: docker容器相关配置(镜像，环境变量，数据卷…)