控制器概念
作者：互联网
1.Replicaset概念
Kubernetes中的ReplicaSet主要的作用是维持一组Pod副本的运行，它的主要作用就是保证一定数量的 Pod 能够在集群中正常运行，它会持续监听这些 Pod 的运行状态，在 Pod 发生故障时重启pod，pod数量减少时重新运行新的 Pod 副本，因此，它通常被用来保证特定数量相同的Pods的可用性。
2.replicaset的工作
ReplicaSet由字段定义，包括一个选择器，该选择器指定如何找到它所管理的Pod、维护多少个pod，以及pod的模板。ReplicaSet通过创建和删除Pod来满足期望的pod数量。当ReplicaSet需要创建新的Pod时，它将使用其Pod模板。ReplicaSet通过Pods的metadata.ownerReferences字段链接到其Pod，该字段指定当前对象所拥有的资源。由ReplicaSet获取的所有Pod在其ownerReferences字段中都有其自己的ReplicaSet的标识信息。通过此链接，ReplicaSet可以知道它正在维护的Pod的状态，并据此计划。
ReplicaSet通过使用其选择器标识要获取的新Pod。如果存在没有OwnerReference的Pod或OwnerReference不是控制器，并且它与ReplicaSet的选择器匹配，它将由所述的ReplicaSet立即获取
3.使用replicaset
replicaSet确保在任何给定时间都运行指定数量的Pod副本。但是，Deployment是一个高级概念，用于管理副本集，并提供对Pod的声明性更新以及许多其他有用的功能。因此，除非你需要自定义更新编排或根本不需要更新，否则我们使用Deployment而不是直接使用replicaset。这实际上意味着你可能永远不需要操纵ReplicaSet对象：改用Deployment，然后在spec部分中定义你的应用程序。
帮助
[root@master-1 ~]# kubectl explain replicaset.spec
KIND: ReplicaSet
VERSION: apps/v1
RESOURCE: spec <Object>
DESCRIPTION:
Spec defines the specification of the desired behavior of the ReplicaSet.
More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status
ReplicaSetSpec is the specification of a ReplicaSet.
FIELDS:
minReadySeconds <integer> 准备等待启动pod 最小时间秒整数
Minimum number of seconds for which a newly created pod should be ready
without any of its container crashing, for it to be considered available.
Defaults to 0 (pod will be considered available as soon as it is ready)
replicas <integer> 副本个数
Replicas is the number of desired replicas. This is a pointer to
distinguish between explicit zero and unspecified. Defaults to 1. More
info:
https://kubernetes.io/docs/concepts/workloads/controllers/replicationcontroller/#what-is-a-replicationcontroller
selector <Object> -required- 标签选择器
Selector is a label query over pods that should match the replica count.
Label keys and values that must match in order to be controlled by this
replica set. It must match the pod template's labels. More info:
https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#label-selectors
template <Object> pod 的定义
Template is the object that describes the pod that will be created if
insufficient replicas are detected. More info:
https://kubernetes.io/docs/concepts/workloads/controllers/replicationcontroller#pod-template
创建名称空间
kubectl create ns replicaset
编写replicaset yaml 并运行
apiVersion: apps/v1 #api 版本
kind: ReplicaSet #资源类型
metadata: #元数据
annotations: #注解
dev: replicaset
name: replicasetchenxi #控制器名字 不允许大小写同时出现
namespace: replicaset # 所在的名称空间
labels: # 标签
dev: ReplicaSet-test
spec: #期望状态
minReadySeconds: 8 # 新创建的 pod 等待就绪的最小秒数
replicas: 5 # 副本数量
selector: # 标签选择器设置
matchLabels: # 使用的标签选择器，标签选择器有matchExpressions、matchLabels
dev: chenxi # 设置匹配的标签
template: # 控制器控制pod 的所有属性
metadata: # pod 的元数据
labels: # 设置pod 标签
dev: chenxi #具体值必须与控制器设置的选择的标签值一至否则控制器不停重启pod
spec: #pod 的期望状态
containers: # 容器属性
- name: web # 容器名字
image: nginx # 容器镜像
imagePullPolicy: IfNotPresent #拉取镜像的策略
ports: # 容器端口设置
- name: web # 端口名字
containerPort: 80 # 容器端口
livenessProbe: # 存活性探测
httpGet: # 探针的设置
port: web # 探测端口设置
path: index.html #探测url
运行查看
[root@master-1 kongzhiqi]# kubectl apply -f replicaset.yaml replicaset.apps/replicasetchenxi created [root@master-1 kongzhiqi]# kubectl get pod -n replicaset pod名字继承控制器名字 NAME READY STATUS RESTARTS AGE replicasetchenxi-4bs2r 1/1 Running 0 93s replicasetchenxi-8qkfl 1/1 Running 0 93s replicasetchenxi-dslcp 1/1 Running 0 93s replicasetchenxi-f6dmw 1/1 Running 0 93s replicasetchenxi-xsm2d 1/1 Running 0 93s
查看控制器
[root@master-1 kongzhiqi]# kubectl get replicaset -n replicaset NAME DESIRED CURRENT READY AGE replicasetchenxi 5 5 5 3m46s [root@master-1 kongzhiqi]# kubectl get replicaset -n replicaset -o wide NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR replicasetchenxi 5 5 5 3m59s web nginx dev=chenxi
删除pod 自动恢复
[root@master-1 kongzhiqi]# kubectl get pod -n replicaset NAME READY STATUS RESTARTS AGE replicasetchenxi-69xtv 1/1 Running 0 18s replicasetchenxi-8qkfl 1/1 Running 0 14m replicasetchenxi-dslcp 1/1 Running 0 14m replicasetchenxi-f6dmw 1/1 Running 0 14m replicasetchenxi-xsm2d 1/1 Running 0 14m [root@master-1 kongzhiqi]# kubectl delete pod -n replicaset replicasetchenxi-8qkfl ＃删除指定pod pod "replicasetchenxi-8qkfl" deleted [root@master-1 kongzhiqi]# kubectl get pod -n replicaset NAME READY STATUS RESTARTS AGE replicasetchenxi-69xtv 1/1 Running 0 118s replicasetchenxi-6ghvl 1/1 Running 0 6s replicasetchenxi-dslcp 1/1 Running 0 15m replicasetchenxi-f6dmw 1/1 Running 0 15m replicasetchenxi-xsm2d 1/1 Running 0 15m
1.Deployment概念
Deployment控制器为 Pod 和 ReplicaSet 提供了一个声明式更新的方法，在Deployment对象中描述一个期望的状态，Deployment控制器就会按照一定的控制速率把实际状态改成期望状态，通过定义一个Deployment控制器会创建一个新的ReplicaSets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，Deployment可以用来管理上面说到的那种蓝绿发布情况的，建立在rs之上的，一个Deployment可以管理多个rs，有多个rs存在，但实际运行的只有一个，当你更新到一个新版本的时候，只是创建了一个新的rs，把旧的rs替换掉了
Deployment可以使用声明式定义，直接在命令行通过纯命令的方式完成对应资源版本的内容的修改，也就是通过打补丁的方式进行修改；Deployment能提供滚动式自定义自控制的更新；对Deployment来讲，我们在实现更新时还可以实现控制更新节奏和更新逻辑，比如说ReplicaSet控制5个pod副本，pod的期望值是5个，但是升级的时候需要额外多几个pod，那么我们控制器可以控制在5个pod副本之外还能再增加几个pod副本；比方说能多一个，但是不能少，那么升级的时候就是先增加一个，再删除一个，增加一个删除一个，始终保持pod副本数是5个，但是有个别交叉之间是6个；还有一种情况，最多允许多一个，最少允许少一个，也就是最多6个，最少4个，第一次加一个，删除两个，第二次加两个，删除两个，依次类推，可以自己控制更新方式，这种是滚动更新的，需要加readinessProbe和livenessProbe探测，确保pod中容器里的应用都正常启动了才删除之前的pod；启动的第一步，刚更新第一批就暂停了也可以；假如目标是5个，允许一个也不能少，允许最多可以10个，那一次加5个即可；这就是我们可以自己控制节奏来控制更新的方法
典型的使用场景：
1)创建无状态的应用
2)滚动更新和回滚
帮助
KIND: Deployment
VERSION: apps/v1
RESOURCE: spec <Object>
DESCRIPTION:
Specification of the desired behavior of the Deployment.
DeploymentSpec is the specification of the desired behavior of the
Deployment.
FIELDS:
minReadySeconds <integer> 等待就绪时间
Minimum number of seconds for which a newly created pod should be ready
without any of its container crashing, for it to be considered available.
Defaults to 0 (pod will be considered available as soon as it is ready)
paused <boolean> 表示部署已暂停。
Indicates that the deployment is paused.
progressDeadlineSeconds <integer> 部署在完成之前取得进展的最长时间
The maximum time in seconds for a deployment to make progress before it is
considered to be failed. The deployment controller will continue to process
failed deployments and a condition with a ProgressDeadlineExceeded reason
will be surfaced in the deployment status. Note that progress will not be
estimated during the time a deployment is paused. Defaults to 600s.
replicas <integer> 副本个数
Number of desired pods. This is a pointer to distinguish between explicit
zero and not specified. Defaults to 1.
revisionHistoryLimit <integer> 保留历史版本个数
The number of old ReplicaSets to retain to allow rollback. This is a
pointer to distinguish between explicit zero and not specified. Defaults to
10.
selector <Object> -required- 标签选择器
Label selector for pods. Existing ReplicaSets whose pods are selected by
this will be the ones affected by this deployment. It must match the pod
template's labels.
strategy <Object> 更新策略
The deployment strategy to use to replace existing pods with new ones.
template <Object> -required- pod 属性定义
Template describes the pods that will be created.
更新策略帮助
[root@master-1 ~]# kubectl explain deployment.spec.strategy.rollingUpdate
KIND: Deployment
VERSION: apps/v1
RESOURCE: rollingUpdate <Object>
DESCRIPTION:
Rolling update config params. Present only if DeploymentStrategyType =
RollingUpdate.
Spec to control the desired behavior of rolling update.
FIELDS:
maxSurge <string> 可以调度的最大 Pod 数量高于所需数量
The maximum number of pods that can be scheduled above the desired number
of pods. Value can be an absolute number (ex: 5) or a percentage of desired
pods (ex: 10%). This can not be 0 if MaxUnavailable is 0. Absolute number
is calculated from percentage by rounding up. Defaults to 25%. Example:
when this is set to 30%, the new ReplicaSet can be scaled up immediately
when the rolling update starts, such that the total number of old and new
pods do not exceed 130% of desired pods. Once old pods have been killed,
new ReplicaSet can be scaled up further, ensuring that total number of pods
running at any time during the update is at most 130% of desired pods.
maxUnavailable <string> 更新期间不可用的 pod 的最大数量。
The maximum number of pods that can be unavailable during the update. Value
can be an absolute number (ex: 5) or a percentage of desired pods (ex:
10%). Absolute number is calculated from percentage by rounding down. This
can not be 0 if MaxSurge is 0. Defaults to 25%. Example: when this is set
to 30%, the old ReplicaSet can be scaled down to 70% of desired pods
immediately when the rolling update starts. Once new pods are ready, old
ReplicaSet can be scaled down further, followed by scaling up the new
ReplicaSet, ensuring that the total number of pods available at all times
during the update is at least 70% of desired pods.
2.使用Deployment运行一个无状态应用
（1）创建一个nginx deployment
[root@master-1 kongzhiqi]# cat deployment.yaml
apiVersion: apps/v1 #api版本
kind: Deployment #资源类型
metadata: #源数据
name: deployment #控制器名字
namespace: deployment # 所在的名称空间
labels: # 标签的设置
dev: deployment-test
spec: # 控制器期望状态
minReadySeconds: 4 # 等待就绪时间
revisionHistoryLimit: 5 # 保留的历史版本
replicas: 3 # pod 个数
strategy: # 更新策略
rollingUpdate: # 选择更新方式
maxSurge: 5 # 最大的pod 数量比pod个数多
maxUnavailable: 1 # 最大不可用的pod 数量
selector: # 标签选择器
matchLabels: # 标签选择器设定
dev: deployment-test # 标签的key与值的设定
template: # pod 属性定义
metadata: # 元数据
labels: # 标签设定
dev: deployment-test # 标签的key 与值
spec: # pod 的期望状态
containers: # 容器的属性定义
- name: web # 容器的名字
image: nginx:1.9.1 # 运行的镜像
imagePullPolicy: IfNotPresent # 获取镜像策略
ports: # 端口设置
- name: web # 端口的名字
containerPort: 80 # 容器的端口
livenessProbe: # 存活性探测属性设置
httpGet: # 探测类型
port: web # 探测的端口
path: index.html # 探测的url
initialDelaySeconds: 5 # 容器里进程初始化时间等待探测时间
periodSeconds: 5 # 探测周期
timeoutSeconds: 2 #探测超时时间
failureThreshold: 3 # 探测连续失败的最大次数
readinessProbe: # 就绪性探测
httpGet: # 探测的钩子
port: web # 探测的端 口
path: index.html #探测的url
initialDelaySeconds: 5 # 容器里进程初始化时间等待探测时间
periodSeconds: 5 # 探测周期
timeoutSeconds: 2 #探测超时时间
failureThreshold: 3 # 探测连续失败的最大次数
运行
[root@master-1 kongzhiqi]# kubectl apply -f deployment.yaml deployment.apps/deployment created [root@master-1 kongzhiqi]# kubectl get pod -n deployment NAME READY STATUS RESTARTS AGE deployment-68c84ccc46-27mhj 0/1 Running 0 43s deployment-68c84ccc46-67fgn 1/1 Running 0 43s deployment-68c84ccc46-g5wtv 1/1 Running 0 43s [root@master-1 kongzhiqi]# kubectl get pod -n deployment NAME READY STATUS RESTARTS AGE deployment-68c84ccc46-27mhj 0/1 Running 0 43s deployment-68c84ccc46-67fgn 1/1 Running 0 43s deployment-68c84ccc46-g5wtv 1/1 Running 0 43s [root@master-1 kongzhiqi]# kubectl get pod -n deployment NAME READY STATUS RESTARTS AGE deployment-68c84ccc46-27mhj 0/1 Running 0 44s deployment-68c84ccc46-67fgn 1/1 Running 0 44s deployment-68c84ccc46-g5wtv 1/1 Running 0 44s [root@master-1 kongzhiqi]# kubectl get pod -n deployment NAME READY STATUS RESTARTS AGE deployment-68c84ccc46-27mhj 1/1 Running 0 44s deployment-68c84ccc46-67fgn 1/1 Running 0 44s deployment-68c84ccc46-g5wtv 1/1 Running 0 44s
（2）使用kubectl列举关于deployment信息
（3）更新deployment
标签：控制器,ReplicaSet,replicasetchenxi,Deployment,概念,Running,deployment,pod 来源： https://www.cnblogs.com/rdchenxi/p/16590158.html