Deployment介绍
为了更好地解决服务编排的问题，k8s在V1.2版本开始，引入了deployment控制器，值得一提的是，这种控制器并不直接管理pod，
而是通过管理replicaset来间接管理pod，即：deployment管理replicaset，replicaset管理pod。所以deployment比replicaset的功能更强大。
deployment的主要功能有下面几个：
- 支持replicaset的所有功能
- 支持发布的停止、继续
- 支持版本的滚动更新和版本回退
deployment的资源清单文件
apiVersion: apps/v1 #版本号
kind: Deployment #类型
metadata: #元数据
name: #rs名称
namespace: #所属命名空间
labels: #标签
controller: deploy
spec: #详情描述
replicas: #副本数量
revisionHistoryLimit: #保留历史版本，默认是10
paused: #暂停部署，默认是false
progressDeadlineSeconds: #部署超时时间(s)，默认是600
strategy: #策略
type: RollingUpdates #滚动更新策略
rollingUpdate: #滚动更新
maxSurge: #最大额外可以存在的副本数，可以为百分比，也可以为整数
maxUnavaliable: #最大不可用状态的pod的最大值，可以为百分比，也可以为整数
selector: #选择器，通过它指定该控制器管理哪些pod
matchLabels: #Labels匹配规则
app: nginx-pod
matchExpressions: #Expression匹配规则
- {key: app, operator: In, values: [nginx-pod]}
template: #模板，当副本数量不足时，会根据下面的模板创建pod副本
metadata:
labels:
app: nginx-pod
spec:
containers:
- name: nginx
image: nginx:1.17.1
ports:
- containerPort: 80
创建deployment
apiVersion: apps/v1
kind: Deployment
metadata:
name: pc-deployment
namespace: dev
spec:
replicas: 3
selector:
matchLabels:
app: nginx-pod
template:
metadata:
labels:
app: nginx-pod
spec:
containers:
- name: nginx
image: nginx:1.17.1
使用配置文件
[root@master ~]# kubectl create -f pc-deployment.yaml
deployment.apps/pc-deployment created
[root@master ~]# kubectl get deploy -n dev -o wide
NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR
pc-deployment 3/3 3 3 16s nginx nginx:1.17.1 app=nginx-pod
查看deployment控制的rs和pod，发现rs是在deployment之后加了一段字符串，而pod是在rs之后加了一段字符串
[root@master ~]# kubectl get rs -n dev
NAME DESIRED CURRENT READY AGE
pc-deployment-5d89bdfbf9 3 3 3 2m13s
[root@master ~]# kubectl get pod -n dev
NAME READY STATUS RESTARTS AGE
pc-deployment-5d89bdfbf9-k8j9n 1/1 Running 0 2m42s
pc-deployment-5d89bdfbf9-vw87k 1/1 Running 0 2m42s
pc-deployment-5d89bdfbf9-x7nsm 1/1 Running 0 2m42s
deployment功能
扩缩容
方式一：命令行
kubectl scale deploy deploy名称 --replicas=pod数量 -n 命名空间
通过命令行变更pod数量为5个
[root@master ~]# kubectl scale deploy pc-deployment --replicas=5 -n dev
deployment.apps/pc-deployment scaled
[root@master ~]# kubectl get pod -n dev
NAME READY STATUS RESTARTS AGE
pc-deployment-5d89bdfbf9-bhcns 1/1 Running 0 83s
pc-deployment-5d89bdfbf9-cfls7 1/1 Running 0 83s
pc-deployment-5d89bdfbf9-k8j9n 1/1 Running 0 8m54s
pc-deployment-5d89bdfbf9-vw87k 1/1 Running 0 8m54s
pc-deployment-5d89bdfbf9-x7nsm 1/1 Running 0 8m54s
方式二：编辑deploy文件
kubectl edit deploy deploy名字 -n 命名空间
通过编辑deploy文件编辑pod数量为3个
[root@master ~]# kubectl edit deploy pc-deployment -n dev
找到replicas，将其数量改为3
spec:
progressDeadlineSeconds: 600
replicas: 3
[root@master ~]# kubectl get pod -n dev
NAME READY STATUS RESTARTS AGE
pc-deployment-5d89bdfbf9-k8j9n 1/1 Running 0 15m
pc-deployment-5d89bdfbf9-vw87k 1/1 Running 0 15m
pc-deployment-5d89bdfbf9-x7nsm 1/1 Running 0 15m
镜像更新
deployment支持两种镜像更新策略：重建更新和滚动更新（默认），可以通过strategy选项进行配置
strategy：指定新的pod替换旧的pod的策略，支持两个属性：
type：指定策略类型，支持两种策略
Recreate：在创建出新的pod之前会先杀掉所有已存在的pod
RollingUpdate：滚动更新，就是杀死一部分，就启动一部分，在更新过程中，存在两个版本pod
rollingUpdate：当type为RollingUpdate时生效，用于为RollingUpdate设置参数，支持两个属性
maxUnavailable：用来指定在升级过程中不可用pod的最大数量，默认为25%
maxSurge：用来指定在升级过程中可以超过期望的pod的最大数量，默认为25%
重建更新
编辑pc-deployment.yaml，在spec节点下添加更新策略
spec:
strategy: #策略
type: Recreate #重建更新策略
[root@master ~]# vim pc-deployment.yaml
[root@master ~]# kubectl apply -f pc-deployment.yaml
Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
deployment.apps/pc-deployment configured
创建deploy进行验证
#首先记录原本的pod名
[root@master ~]# kubectl get pod -n dev
NAME READY STATUS RESTARTS AGE
pc-deployment-5d89bdfbf9-bqf86 1/1 Running 0 8s
pc-deployment-5d89bdfbf9-kz6jt 1/1 Running 0 8s
pc-deployment-5d89bdfbf9-z7d9z 1/1 Running 0 8s
#更改pod镜像
[root@master ~]# kubectl set image deploy pc-deployment nginx=nginx:1.17.2 -n dev
deployment.apps/pc-deployment image updated
#再次查看镜像
[root@master ~]# kubectl get pod -n dev
NAME READY STATUS RESTARTS AGE
pc-deployment-675d469f8b-b9rwd 1/1 Running 0 27s
pc-deployment-675d469f8b-kc7rr 1/1 Running 0 27s
pc-deployment-675d469f8b-kxgkq 1/1 Running 0 27s
发现pod镜像已经改变了
滚动更新
编辑pc-deployment.yaml，在spec节点下添加滚动更新策略（也可以把strategy去掉，因为默认滚动更新策略）
strategy:
type: RollingUpdate #滚动更新策略
rollingUpdate:
maxUnavailable: 25%
maxSurge: 25%
[root@master ~]# vim pc-deployment.yaml
[root@master ~]# kubectl apply -f pc-deployment.yaml
Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
deployment.apps/pc-deployment configured
创建deploy进行验证
#记录以前的pod
[root@master ~]# kubectl get pod -n dev
NAME READY STATUS RESTARTS AGE
pc-deployment-5d89bdfbf9-526wf 1/1 Running 0 61s
pc-deployment-5d89bdfbf9-b5x5v 1/1 Running 0 64s
pc-deployment-5d89bdfbf9-kc7hb 1/1 Running 0 59s
#更新镜像
[root@master ~]# kubectl set image deploy pc-deployment nginx=nginx:1.17.2 -n dev
deployment.apps/pc-deployment image updated
#查看pod状态
[root@master ~]# kubectl get pod -n dev
NAME READY STATUS RESTARTS AGE
pc-deployment-5d89bdfbf9-526wf 0/1 Terminating 0 2m2s
pc-deployment-5d89bdfbf9-b5x5v 1/1 Running 0 2m5s
pc-deployment-5d89bdfbf9-kc7hb 0/1 Terminating 0 2m
pc-deployment-675d469f8b-7vw6x 1/1 Running 0 3s
pc-deployment-675d469f8b-rzq82 0/1 ContainerCreating 0 2s
pc-deployment-675d469f8b-zk4fs 1/1 Running 0 5s
[root@master ~]# kubectl get pod -n dev
NAME READY STATUS RESTARTS AGE
pc-deployment-675d469f8b-7vw6x 1/1 Running 0 38s
pc-deployment-675d469f8b-rzq82 1/1 Running 0 37s
pc-deployment-675d469f8b-zk4fs 1/1 Running 0 40s
发现pod是旧的一遍停止新的一边创建，最后全变成了新的
滚动更新的过程
滚动更新
镜像更新中rs的变化
前期准备：
#重建deployment
[root@master ~]# kubectl delete -f pc-deployment.yaml
deployment.apps "pc-deployment" deleted
#添加record参数，表明创建时记录
[root@master ~]# kubectl create -f pc-deployment.yaml --record
deployment.apps/pc-deployment created
[root@master ~]# kubectl get deploy,rs,pod -n dev
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/pc-deployment 3/3 3 3 81s
NAME DESIRED CURRENT READY AGE
replicaset.apps/pc-deployment-5d89bdfbf9 3 3 3 81s
NAME READY STATUS RESTARTS AGE
pod/pc-deployment-5d89bdfbf9-4bg2j 1/1 Running 0 81s
pod/pc-deployment-5d89bdfbf9-gbt95 1/1 Running 0 81s
pod/pc-deployment-5d89bdfbf9-tstlh 1/1 Running 0 81s
新建两个xshell窗口，用于监听rs和pod，在2窗口中监听rs，3窗口中监听pod
#在2窗口中输入
[root@master ~]# kubectl get rs -n dev -w
NAME DESIRED CURRENT READY AGE
pc-deployment-5d89bdfbf9 3 3 3 6m18s
#在3窗口中输入
[root@master ~]# kubectl get pod -n dev -w
NAME READY STATUS RESTARTS AGE
pc-deployment-5d89bdfbf9-4bg2j 1/1 Running 0 6m56s
pc-deployment-5d89bdfbf9-gbt95 1/1 Running 0 6m56s
pc-deployment-5d89bdfbf9-tstlh 1/1 Running 0 6m56s
在1窗口中改变pod镜像
[root@master ~]# kubectl set image deploy pc-deployment nginx=nginx:1.17.2 -n dev
deployment.apps/pc-deployment image updated
查看3窗口中pod的变化，发现序号5开头的pod在逐渐暂停，序号6开头的pod在逐渐创建
查看2窗口中rs的变化，可以看见序号5开头的rs的pod数在减少，序号6开头的rs的pod数在增加
在1窗口中查看最终rs变化，发现原来的rs依旧存在，只是pod数量变为了0，而后又新产生了一个rs，pod数量为3，其实这就是deployment能够进行版本回退的奥妙所在，后面会详细解释
[root@master ~]# kubectl get rs -n dev
NAME DESIRED CURRENT READY AGE
pc-deployment-5d89bdfbf9 0 0 0 11m
pc-deployment-675d469f8b 3 3 3 3m12s
版本回退
deployment支持版本升级过程中的暂停，继续功能以及版本回退等诸多功能，下面具体来看
kubectl rollout：版本升级相关功能，支持下面的选项：
- status：显示当前升级状态
- history：显示升级历史记录
- pause：暂停版本升级过程
- resume：继续已经暂停的版本升级过程
- restart：重启版本升级过程
- undo：回滚到上一级版本（可以使用--to-revision回滚到指定版本）
#查看升级状态
[root@master ~]# kubectl rollout status deploy pc-deployment -n dev
deployment "pc-deployment" successfully rolled out
#查看升级历史（注意：如果只显示版本号说明一开始使用yaml创建文件的时候没有加上--record命令）
[root@master ~]# kubectl rollout history deploy pc-deployment -n dev
deployment.apps/pc-deployment
REVISION CHANGE-CAUSE
1 kubectl create --filename=pc-deployment.yaml --record=true
2 kubectl create --filename=pc-deployment.yaml --record=true
#版本回滚
#这里使用--to-revision=1回滚到1版本，如果省略这个选项，则会回退到上个版本
[root@master ~]# kubectl rollout undo deploy pc-deployment --to-revision=1 -n dev
deployment.apps/pc-deployment rolled back
#查看是否回滚成功，发现5序号开头的rs被启动了
[root@master ~]# kubectl get rs -n dev
NAME DESIRED CURRENT READY AGE
pc-deployment-5d89bdfbf9 3 3 3 31m
pc-deployment-675d469f8b 0 0 0 22m
金丝雀发布
deployment支持更新过程中的控制，如"暂停（pause）"或"继续（resume）"更新操作
比如有一批新的pod资源创建完成后立即暂停更新过程，此时，仅存在一部分新版本的应用，主体部分还是旧的版本。然后，再筛选一小部分的用户请求路由到新的pod应用，继续观察能否稳定地按期望的方式运行。确定没问题之后再继续完成余下的pod资源滚动更新，否则立即回滚更新操作。这就是所谓的金丝雀发布。
#更新deployment版本，并配置暂停deployment
[root@master ~]# kubectl set image deploy pc-deployment nginx=nginx:1.17.2 -n dev && kubectl rollout pause deploy pc-deployment -n dev
deployment.apps/pc-deployment image updated
deployment.apps/pc-deployment paused
#查看rs，发现老版本rs没有减少，新版本rs增加一个
[root@master ~]# kubectl get rs -n dev
NAME DESIRED CURRENT READY AGE
pc-deployment-5d89bdfbf9 3 3 3 44m
pc-deployment-675d469f8b 1 1 1 35m
#在窗口2中查看deploy状态，发现deploy正在等待更新且已经有1个更新好了
[root@master ~]# kubectl rollout status deploy pc-deployment -n dev
Waiting for deployment "pc-deployment" rollout to finish: 1 out of 3 new replicas have been updated...
#在窗口1中继续deploy的更新
[root@master ~]# kubectl rollout resume deploy pc-deployment -n dev
deployment.apps/pc-deployment resumed
#查看窗口2的状态
Waiting for deployment spec update to be observed...
Waiting for deployment spec update to be observed...
Waiting for deployment "pc-deployment" rollout to finish: 1 out of 3 new replicas have been updated...
Waiting for deployment "pc-deployment" rollout to finish: 1 out of 3 new replicas have been updated...
Waiting for deployment "pc-deployment" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "pc-deployment" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "pc-deployment" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "pc-deployment" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "pc-deployment" rollout to finish: 1 old replicas are pending termination...
deployment "pc-deployment" successfully rolled out
#在窗口1查看rs更新结果，发现老版本均停止，新版本已经创建好
[root@master ~]# kubectl get rs -n dev
NAME DESIRED CURRENT READY AGE
pc-deployment-5d89bdfbf9 0 0 0 49m
pc-deployment-675d469f8b 3 3 3 40m
