【云原生】Deployment控制器具体
Deployment一、Deployment
1.1、什么是Deployment
[*]Deployment同样也是Kubernetes系统的一个核心概念，主要职责和RC、RS一样都是保证Pod的数目和健康，通过定义一个Deployment控制器会创建一个新的ReplicaSet控制器，通过ReplicaSet创建Pod，删除Deployment控制器，也会删除Deployment控制器下对应的ReplicaSet控制器和Pod资源。二则大部分功能都是完全同等的，我们可以看成是一个升级版的RC、RS控制器
1.2、Deployment功能
[*]声明式更新：用户可以声明所需的应用状态，Deployment控制器负责将当前徐徐更为所需状态。
[*]自动滚动更新：Deployment支持在更新应用时实行更新。使得应用的可用性持续，该过程会徐徐替换旧版本的Pod，确保在更新过程中不会有或少少有downtime。
[*]回滚功能：如果新的应用版本出现题目，Deployment允许用户快速回滚到先前的稳定版本。
[*]管理副本：Deployment控制器恶意维护指定数目的Pod副本，确保系统在任何时刻都有足够的副本在运行。
[*]自愈能力：Deployment会监控Pod的状态，并自动重启失败的Pod，以保持设定的副本数。
[*]版本控制：Deployment使用标签选择器来管理Pod，这使得用户可以很容器地跟踪和管理差别版本的应用。
1.3、Deployment用例场景
[*]创建Deployment以将ReplicaSet上线。ReplicaSet在后台创建Pod。查抄ReplicaSet的上线状态，查察其是否成功。
[*]通过更新Deployment的PodTemplateSpec，声明Pod的新状态。新的ReplicaSet会被创建，Deployment以受控速率将Pod从旧ReplicaSet迁移到新ReplicaSet。每个新的ReplicaSet都会更新Deployment的修订版本。
[*]如果Deployment的当前状态不稳定，回滚到较早的Deployment版本。每次回滚都会更新Deployment的修订版本。
[*]扩大Deployment规模以承担更多负载。
[*]停息Deployment的上线以应用对PodTemplateSpec所作的多项修改，然后规复实在行以启动新的上线版本。
[*]使用Deployment状态来判断上线过程是否出现停滞。
[*]清理较久的不再必要的ReplicaSet。
二、Deployment示例
2.1、示例
[*]下面的Deployment示例，其中创建了一个ReplicaSet，这个ReplicaSet负责启动三个nginxPod：
# vim nginx-deployment.yaml
apiVersion: "apps/v1"
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
restartPolicy: Always
containers:
- name: nginx
image: nginx:1.14.2
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
[*]在该例中：
[*]创建名为nginx-deployment（由.metadata.name字段标明）的Deployment。该名称将成为后续创建ReplicaSet和Pod的名称底子
[*]该Deployment创建一个ReplicaSet，它创建三个（由.spec.replicas字段标明）Pod副本。
[*].spec.selector字段定义所创建的ReplicaSet如果查找要管理的Pod。在这里，你选择在Pod模板中定义的标签（app:nginx）。不过，更复杂的选择规则是也大概的，只要Pod模板本身满意所给规则即可。
[*]template字段包罗以下子字段：
[*]Pod被使用.metadata.labels字段打上app:nginx标签。
[*]Pod模板规约（即.template.spec字段）指示Pod运行一个nginx容器，该容器运行版本为1.14.2的nginxDocker Hub镜像。
[*]创建一个容器并使用.spec.template.spec.containers.name字段将其命名为nginx
[*]开始之前，请确保你的Kubernetes集群已经正常运行。按照以下步骤创建上述Deployment
# kubectl apply -f nginx-deployment.yaml
[*]运行kubectl get deployment查抄Deployment是否已经创建。如果仍在创建Deployment，则输出类似于：
# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deployment 0/3 3 0 25s
# 在检查集群中的Deployment时，所显示的字段有：
NAME：列出了名称空间中Deployment的名称
READY：显示应用程序的可用“副本”数。显示的模式是“就绪个数/期望个数”
UP-TO-DATE：显示为了达到期望状态已经更新的副本数
AVAILABLE：显示应用可供用户使用的副本数
AGE：显示应用程序运行的时间
[*]请注意期望数副本数是根据.spec.replicas字段设置3
要想查察Deployment上线状态，运行kubectl rollout status deployment nginx-deployment
# kubectl rollout status deployment nginx-deployment
deployment "nginx-deployment" successfully rolled out
几秒种过再次运行kubectl get deployment输出类似于：
# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deployment 3/3 3 3 71m
要查察Deployment创建的ReplicaSet(rs)，运行kubectl get rs。输出类似于
# kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-deployment-9456bbbf9 3 3 3 73m
# ReplicaSet输出中包含以下字段：
NAME：列出名称空间中ReplicaSet的名称
DESIRED：显示应用的期望副本个数，即在创建Deployment时所定义的值。此为期望状态
CURRENT：显示当前运行状态中的副本个数
READY：显示应用中有多少副本可以为用户提供服务
AGE：显示应用已经运行的时间长度
# 注意：ReplicaSet的名称格式始终为-[哈希]。该名称将成为所创建的Pod的名称基础。其中的 哈希字符串与ReplicaSet上的pod-template-hash标签一致
# Deployment的名字
# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deployment 3/3 3 3 77m
# rs的名字
# kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-deployment-9456bbbf9 3 3 3 77m
要查察每个Pod自动天生的标签，运行kubectl get pod --show-labels。输出类似于
# kubectl get pod
--show-labels
NAME READY STATUS RESTARTS AGE LABELS
nginx-deployment-9456bbbf9-j855n 1/1 Running 0 78m app=nginx,pod-template-hash=9456bbbf9
nginx-deployment-9456bbbf9-kzxkw 1/1 Running 0 78m app=nginx,pod-template-hash=9456bbbf9
nginx-deployment-9456bbbf9-twsbk 1/1 Running 0 78m app=nginx,pod-template-hash=9456bbbf9
2.2、说明
你必须在Deployment中指定得当的选择算符和Pod模板标签（在本例中为app:nginx）。标签大概选择算符不要与其他控制器（包括其他Deployment和StatefulSet）重叠。Kubernetes不会组织你如许做，但是如果多个控制器具有重叠的选择算符，它们大概会发生冲突实行难以预料的操作。
2.3、Pod-template-hash标签
注意：不要更改此标签
Deployment控制器将pod-template-hash标签添加到Deployment所创建或收留的每个ReplicaSet
此标签可确保Deployment的子ReplicaSet不重叠。标签是通过对ReplicaSet的podTemplate举行哈希处理。所天生的哈希值被添加到ReplicaSet选择算符、Pod模板标签，并存在于ReplicaSet大概拥有的任何现有Pod中
三、更新Deployment
说明：仅当Deployment Pod模板(即.spec.template)发生该表时，比方模板的标签或容器镜像被更新，才会触发Deployment上线。其他更新（如对Deployment实行扩缩容的操作）不会指出上线动作。
3.1、更新Nginx版本
再实行以下操作之前，可以先查察目前的nginx版本
# kubectl exec -it nginx-deployment-9456bbbf9-j855n -- nginx -v
nginx version: nginx/1.14.2
先来更新nginx Pod以使用nginx:1.16.1镜像，而不是nginx:1.14.2镜像
# kubectl set image deployment nginx-deployment nginx=nginx:1.16.1
在这里，deployment nginx-deployment表明Deployment的名称，nginx表明必要举行更新的容器，而nginx:1.16.1则表示镜像的心版本
输出类似于：
deployment.apps/nginx-deployment image updated
大概，可以对Deployment实行edit操作并将.spec.template.spec.containers.image从nginx:1.14.2更改值nginx:latest最新版本
# kubectl edit deployment nginx-deployment
spec:
containers:
- image: nginx:latest
imagePullPolicy: IfNotPresent
name: nginx
...
3.2、查察上线状态
要查察上线状态，运行：
# kubectl rollout status deployment nginx-deployment
输出类似于
Waiting for deployment "nginx-deployment" rollout to finish: 1 out of 3 new replicas have been updated...
大概
deployment "nginx-deployment" successfully rolled out
获取关于已更新的Deployment的更多信息
[*]在上线成功后，可以通过运行kubectl get deployment来查察Deployment：输出类似于：
# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deployment 3/3 3 3 110m
[*]运行kubectl get rs以查察Deployment通过创建新的ReplicaSet并将其扩容到3个副本并将旧ReplicaSet缩容到0个副本完成了Pod的更新操作：
# kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-deployment-67dffbbbb 3 3 3 2m52s
nginx-deployment-9456bbbf9 0 0 0 111m
[*]现在运行kubectl get pod应该显示新的Pod：
# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-deployment-67dffbbbb-2dgln 1/1 Running 0 3m54s
nginx-deployment-67dffbbbb-kmsbr 1/1 Running 0 3m55s
nginx-deployment-67dffbbbb-sg672 1/1 Running 0 3m56s
下次要更新这些Pod时，只必要再次更新Deployment模板即可。
Deployment可确保在更新时关闭肯定数目的Pod。默认情况下，它确保至少所需Pod的75%处于运行状态（最大不可用比例为25%）。
比方，如果仔细查察上述Deployment，将看到它起首创建了一个新的Pod，然后删除旧的Pod，并创建了新的Pod。它不会杀死旧Pod，直到足够数目的新Pod已经出现。在足够数目的旧Pod被杀死前并没有创建新的Pod。它确保至少3个Pod可用，同时最多总共4个Pod可用。当Deployment设置为4个副本时，Pod的个数会介于3和5之前。
[*]获取Deployment的更多信息
# kubectl describe deployment
输出类似于
Name: nginx-deployment
Namespace: default
CreationTimestamp: Fri, 26 Jul 2024 15:42:14 +0800
Labels: app=nginx
Annotations: deployment.kubernetes.io/revision: 3
Selector: app=nginx
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy:25% max unavailable, 25% max surge
Pod Template:
Labels:app=nginx
Containers:
nginx:
Image: nginx:latest
Port: 80/TCP
Host Port: 0/TCP
Environment:<none>
Mounts: <none>
Volumes: <none>
Conditions:
Type StatusReason
---- ------------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets:<none>
NewReplicaSet: nginx-deployment-67dffbbbb (3/3 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
NormalScalingReplicaSet22m deployment-controllerScaled up replica set nginx-deployment-ff6655784 to 1
NormalScalingReplicaSet7m43sdeployment-controllerScaled down replica set nginx-deployment-ff6655784 to 0
NormalScalingReplicaSet7m43sdeployment-controllerScaled up replica set nginx-deployment-67dffbbbb to 1
NormalScalingReplicaSet7m42sdeployment-controllerScaled down replica set nginx-deployment-9456bbbf9 to 2
NormalScalingReplicaSet7m42sdeployment-controllerScaled up replica set nginx-deployment-67dffbbbb to 2
NormalScalingReplicaSet7m41sdeployment-controllerScaled down replica set nginx-deployment-9456bbbf9 to 1
NormalScalingReplicaSet7m41sdeployment-controllerScaled up replica set nginx-deployment-67dffbbbb to 3
NormalScalingReplicaSet7m39sdeployment-controllerScaled down replica set nginx-deployment-9456bbbf9 to 0
四、回滚Deployment
4.1、回滚前操作
偶然，你大概想要回滚Deployment；比方，当Deployment不稳定时(比方进入反复崩溃状态)。默认情况下，Deployment的全部上线记录都保留在系统中，以便可以随时回滚（你可以通过修改修订历史限定来更新这一越苏）
说明：Deployment被触发上线时，系统就会创建Deployment的新的修订版本。这意味着仅当Deployment的Pod模板(.spec.template)发生更改时，才会创建新的修订版本–比方，模板的标签或容器镜像发生变化。其他更新，如Deployment的扩缩容器操作不会创建Deployment修订版本。这是为了方便同时实行手动缩放或自动缩放，换言之，当你回滚到较早的修订版本时，只有Deployment的Pod模板部署会被回滚。
[*]假设你在更新Deployment时犯了一个拼写错误，将镜像名称命名设置为nginx:1.161而不是nginx:1.16.1
# kubectl set image deployment nginx-deployment nginx=nginx:1.161
输出类似于：
deployment.apps/nginx-deployment image updated
[*]此上线进程会出现停滞，你可以通过查抄上线状态来验证：
# kubectl rollout status deployment nginx-deployment
输出类似于
Waiting for deployment "nginx-deployment" rollout to finish: 1 out of 3 new replicas have been updated...
[*] 按Ctrl-C制止上述上线状态观察
[*] 你可以看到旧的副本有3个，新的副本有1个
# kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-deployment-5b4685b9bd 1 1 0 3m56s
nginx-deployment-67dffbbbb 3 3 3 20m
nginx-deployment-9456bbbf9 0 0 0 128m
[*]查察所创建的Pod，你会注意到新ReplicaSet所创建的1个Pod卡顿在镜像拉取循环中
# kubectl get pod
输出类似于：
NAME READY STATUS RESTARTS AGE
nginx-deployment-5b4685b9bd-lm4jj 0/1 ImagePullBackOff 0 5m21s
nginx-deployment-67dffbbbb-2dgln 1/1 Running 0 21m
nginx-deployment-67dffbbbb-kmsbr 1/1 Running 0 21m
nginx-deployment-67dffbbbb-sg672 1/1 Running 0 21m
说明：Deployment控制器自动制止有题目的上线过程，并制止对新的ReplicaSet扩容。这行为取决于所指定的rollingUpdate参数（具体为maxUnavailable）。默认情况下，Kubernetes将此值设置为25%
[*]获取Deployment描述信息：
# kubectl describe deployment
输出类似于：
Name: nginx-deployment
Namespace: default
CreationTimestamp: Fri, 26 Jul 2024 15:42:14 +0800
Labels: app=nginx
Annotations: deployment.kubernetes.io/revision: 4
Selector: app=nginx
Replicas: 3 desired | 1 updated | 4 total | 3 available | 1 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy:25% max unavailable, 25% max surge
Pod Template:
Labels:app=nginx
Containers:
nginx:
Image: nginx:1.161
Port: 80/TCP
Host Port: 0/TCP
Environment:<none>
Mounts: <none>
Volumes: <none>
Conditions:
Type StatusReason
---- ------------
Available True MinimumReplicasAvailable
Progressing True ReplicaSetUpdated
OldReplicaSets:nginx-deployment-67dffbbbb (3/3 replicas created)
NewReplicaSet: nginx-deployment-5b4685b9bd (1/1 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
NormalScalingReplicaSet39m deployment-controllerScaled up replica set nginx-deployment-ff6655784 to 1
NormalScalingReplicaSet24m deployment-controllerScaled down replica set nginx-deployment-ff6655784 to 0
NormalScalingReplicaSet24m deployment-controllerScaled up replica set nginx-deployment-67dffbbbb to 1
NormalScalingReplicaSet24m deployment-controllerScaled down replica set nginx-deployment-9456bbbf9 to 2
NormalScalingReplicaSet24m deployment-controllerScaled up replica set nginx-deployment-67dffbbbb to 2
NormalScalingReplicaSet24m deployment-controllerScaled down replica set nginx-deployment-9456bbbf9 to 1
NormalScalingReplicaSet24m deployment-controllerScaled up replica set nginx-deployment-67dffbbbb to 3
NormalScalingReplicaSet24m deployment-controllerScaled down replica set nginx-deployment-9456bbbf9 to 0
NormalScalingReplicaSet7m44sdeployment-controllerScaled up replica set nginx-deployment-5b4685b9bd to 1
要办理此题目，必要回滚到以前稳定的Deployment版本
4.2、查抄Deployment上线历史
4.2.1、查察修订历史
# kubectl rollout history deployment nginx-deployment
输出类似于：
deployment.apps/nginx-deployment
REVISIONCHANGE-CAUSE
1 <none>
2 <none>
3 <none>
4 <none>
CHANGE-CAUSE的内容是从Deployment的kubernetes.io/change-cause注解复制过来的。复制动作发生在修订版本创建时。
4.2.2、查察修订历史的具体信息
[*]以下命令将查察修订版本2的具体信息
# kubectl rollout history deployment nginx-deployment
--revision=2 输出类似于：
deployment.apps/nginx-deployment with revision #2
Pod Template:
Labels: app=nginx
pod-template-hash=ff6655784
Containers:
nginx:
Image: nginx:1.16.1
Port: 80/TCP
Host Port: 0/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
4.2.3、回滚到之前的修订版本
按照下面给出的步骤将Deployment从当前版本回滚到以前的版本（即版本2）
[*]假定现在你已经决定撤销当前上线版本回滚到之前的修订版本：
# kubectl rollout undo deployment nginx-deployment --to-revision=2
输出类似于：
deployment.apps/nginx-deployment rolled back
[*]查抄回滚是否成功以及Deployment是否正在运行
# kubectl get deployment nginx-deployment
输出类似于：
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deployment 3/3 3 3 3h43m
[*]获取Deployment描述信息：
# kubectl describe deployment
nginx-deployment 输出类似于：
Name: nginx-deployment
Namespace: default
CreationTimestamp: Fri, 26 Jul 2024 15:42:14 +0800
Labels: app=nginx
Annotations: deployment.kubernetes.io/revision: 5
Selector: app=nginx
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy:25% max unavailable, 25% max surge
Pod Template:
Labels:app=nginx
Containers:
nginx:
Image: nginx:1.16.1
Port: 80/TCP
Host Port: 0/TCP
Environment:<none>
Mounts: <none>
Volumes: <none>
Conditions:
Type StatusReason
---- ------------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets:<none>
NewReplicaSet: nginx-deployment-ff6655784 (3/3 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
NormalScalingReplicaSet131m deployment-controllerScaled up replica set nginx-deployment-ff6655784 to 1
NormalScalingReplicaSet115m deployment-controllerScaled down replica set nginx-deployment-ff6655784 to 0
NormalScalingReplicaSet115m deployment-controllerScaled up replica set nginx-deployment-67dffbbbb to 1
NormalScalingReplicaSet115m deployment-controllerScaled down replica set nginx-deployment-9456bbbf9 to 2
NormalScalingReplicaSet115m deployment-controllerScaled up replica set nginx-deployment-67dffbbbb to 2
NormalScalingReplicaSet115m deployment-controllerScaled down replica set nginx-deployment-9456bbbf9 to 1
NormalScalingReplicaSet115m deployment-controllerScaled up replica set nginx-deployment-67dffbbbb to 3
NormalScalingReplicaSet115m deployment-controllerScaled down replica set nginx-deployment-9456bbbf9 to 0
NormalScalingReplicaSet99m deployment-controllerScaled up replica set nginx-deployment-5b4685b9bd to 1
NormalScalingReplicaSet3m55sdeployment-controllerScaled down replica set nginx-deployment-5b4685b9bd to 0
NormalScalingReplicaSet3m55sdeployment-controllerScaled up replica set nginx-deployment-ff6655784 to 1
NormalScalingReplicaSet3m10sdeployment-controllerScaled down replica set nginx-deployment-67dffbbbb to 2
NormalScalingReplicaSet3m10sdeployment-controllerScaled up replica set nginx-deployment-ff6655784 to 2
NormalScalingReplicaSet2m30sdeployment-controllerScaled down replica set nginx-deployment-67dffbbbb to 1
NormalScalingReplicaSet2m30sdeployment-controllerScaled up replica set nginx-deployment-ff6655784 to 3
NormalScalingReplicaSet2m28sdeployment-controllerScaled down replica set nginx-deployment-67dffbbbb to 0
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