文章目录

调度方式
- nodeName方式
- nodeSelect方式
- 故障排除
控制器
- Deployment
- SatefulSet
- DaemonSet
- Job
- CronJob
常规service不同于无头服务
- service
- headless方式
k8s配置管理
- Secret
- ConfigMap

调度方式

用于调度pod相应的资源调度node可自动分配或指定

nodeName：用于将pod调度到指定node上(跳过调度器直接分配)
nodeSelect：用于将pod调度到匹配label的node上

nodeName方式

用于将pod调度到指定node上(跳过调度器直接分配)

[root@master demo]# vim pod-ns.yaml apiVersion: v1 kind: Pod metadata:   name: pod-example   labels:     app: nginx spec:   nodeName: 20.0.0.30   containers:   - name: nginx image: nginx:1.15

查看细节，看到events中间没有调度器scheduler

[root@master demo]# kubectl get pods -o wide NAME          READY   STATUS    RESTARTS   AGE    IP           NODE        NOMINATED NODE pod-example   1/1     Running   0          108s   172.17.3.3   20.0.0.30   <none> [root@master demo]# kubectl describe pod pod-example Events:   Type    Reason   Age    From                Message   ----    ------   ----   ----                -------   Normal  Pulling  3m55s  kubelet, 20.0.0.30  pulling image "nginx:1.15"   Normal  Pulled   3m25s  kubelet, 20.0.0.30  Successfully pulled image "nginx:1.15"   Normal  Created  3m25s  kubelet, 20.0.0.30  Created container   Normal  Started  3m25s  kubelet, 20.0.0.30  Started container

nodeSelect方式

用于将pod调度到匹配label的node上

[root@master demo]# kubectl get nodes NAME        STATUS   ROLES    AGE   VERSION 20.0.0.30   Ready    <none>   14d   v1.12.3 20.0.0.40   Ready    <none>   14d   v1.12.3 [root@master demo]# kubectl label nodes 20.0.0.30 njit=a node/20.0.0.30 labeled [root@master demo]# kubectl label nodes 20.0.0.40 njit=b node/20.0.0.40 labeled [root@master demo]# kubectl get nodes --show-labels NAME        STATUS   ROLES    AGE   VERSION   LABELS 20.0.0.30   Ready    <none>   14d   v1.12.3   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=20.0.0.30,njit=a 20.0.0.40   Ready    <none>   14d   v1.12.3   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=20.0.0.40,njit=b [root@master demo]# vim pod-ns.yaml  apiVersion: v1 kind: Pod metadata:   name: pod-example   labels:     app: nginx spec:   nodeSelector:     njit: b   containers:   - name: nginx     image: nginx:1.15 [root@master demo]# kubectl get pods NAME          READY   STATUS    RESTARTS   AGE pod-example   1/1     Running   0          83s 查看详细事件，看到events记录通过了scheduler [root@master demo]# kubectl describe pod pod-example Events:   Type    Reason     Age   From                Message   ----    ------     ----  ----                -------   Normal  Scheduled  2m2s  default-scheduler   Successfully assigned default/pod-example to 20.0.0.40   Normal  Pulling    2m1s  kubelet, 20.0.0.40  pulling image "nginx:1.15"   Normal  Pulled     98s   kubelet, 20.0.0.40  Successfully pulled image "nginx:1.15"   Normal  Created    97s   kubelet, 20.0.0.40  Created container   Normal  Started    97s   kubelet, 20.0.0.40  Started container

故障排除

值	描述
Pending	Pod已提交创建Kubernetes。但由于某种原因，无法顺利创建。比如下载镜像慢，调度不成功。
Running	Pod已绑定到一个节点，并创建了所有的容器。至少有一个容器正在运行，或正在启动或重新启动。.
Succeeded	Pod所有容器都成功终止，不会重新启动。
Failed	Pod所有容器都终止了，至少有一个容器在故障中终止了。也就是说，容器要么以非零状态退出，要么被系统终止。
Unknown	由于某种原因apiserver无法获得Pod通常是因为Master与 Pod所在主机kubelet通信错误。

控制器

控制器：又称工作负载，包括以下五种控制器

Deployment
StatefulSet
DaemonSet
Job
CronJob

controllers:管理和运行集群上的容器label-select相关联 pod通过控制器实现应用的运维，如伸缩，升级等

Deployment

部署无状态应用程序，没有特定的角色，任何可以替代另一个/li>
管理pod和replicaset
具有上线部署、副本设定、滚动升级、回滚等功能
提供声明式更新，例如只更新一个新的image

应用场景：web服务

[root@master demo]# 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:
      containers:
      - name: nginx
        image: nginx:1.15.4
        ports:
        - containerPort: 80
[root@master demo]# kubectl create -f nginx-deployment.yaml
deployment.apps/nginx-deployment created

查看deploy控制器，rs副本集

[root@master demo]# kubectl get pods,deploy,rs
NAME                                  READY   STATUS    RESTARTS   AGE
pod/nginx-deployment-d55b94fd-4fdkj   1/1     Running   0          81s
pod/nginx-deployment-d55b94fd-947w9   1/1     Running   0          81s
pod/nginx-deployment-d55b94fd-h2jkh   1/1     Running   0          81s
pod/pod-example                       1/1     Running   0          13h

NAME                                     DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deployment.extensions/nginx-deployment   3         3         3            3           82s

NAME                                              DESIRED   CURRENT   READY   AGE
replicaset.extensions/nginx-deployment-d55b94fd   3         3         3       81s

查看控制器，其中replicaset可以控制版本更新，副本数，回滚

[root@master demo]# kubectl edit deployment/nginx-deployment
spec:
  progressDeadlineSeconds: 600
  replicas: 3
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: nginx
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
type: RollingUpdate

其中strategy中定义滚动更新rollingUpdate maxSurge为25%，表示如果有100个pod，进行业务更新时在原来的基础上最多多创建25个pod达到125个pod maxUnavailable为25%，表示如果有100个pod，进行业务更新时，最多删除原来的pod25个， maxUnavailable这个值一定要小于maxSurge的限度，因为在副本集的限制下pod的数量保持一定的数量，要是删除太多，就恢复创建不回来了

查看历史版本

[root@master demo]# kubectl rollout history deployment/nginx-deployment
deployment.extensions/nginx-deployment 
REVISION  CHANGE-CAUSE
1         <none>

SatefulSet

部署有状态化应用，pod是有特定角色的，如主从关系
解决pod独立生命周期，保持pod启动顺序和唯一性
稳定，唯一的网络标识符，持久化存储（例如：etcd配置文件，节点地址发生变化，将无法使用）
有序，有序的部署和扩展、删除和终止（例如：mysql主从关系，先启动主，再启动从）有序，滚动更新
应用场景：数据库

无状态： 1.deployment认为所有的pod都是一样的 2.不用考虑顺序的要求 3.不用考虑在哪个pod节点上运行 4.可以随意扩容和缩容

有状态： 1.实例之间有差别，每个实例都有自己的独特性，元数据不同，例如etcd，zookeeper 2.实例之间不对等的关系，以及依靠外部存储的应用

DaemonSet

在每个node上运行一个pod 新加入的node也同样会自动运行一个pod 引用场景：Agent https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/

Job

Job分为普通任务（Job）和定时任务（CronJob）一次性执行应用场景：离线数据处理，视频解码等业务 https://kubernetes.io/docs/concepts/workloads/controllers/jobs-run-to-completion/

CronJob

周期性任务周期性任务应用场景：通知，备份 https://kubernetes.io/docs/tasks/job/automated-tasks-with-cron-jobs/

常规service和无头服务区别

service：一组pod访问策略，提供cluster-ip群集之间的通信，还提供负载均衡和服务发现 headless service ：无头服务，不需要cluster-ip，直接绑定具体的pod的ip

service

[root@master demo]# kubectl get svc
NAME            TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
kubernetes      ClusterIP   10.0.0.1     <none>        443/TCP        15d
nginx-service   NodePort    10.0.0.223   <none>        80:42524/TCP   8m57s
在node节点上，使用cluster-ip进行群集间通信，要是不能通信尝试iptables -F和setenforce 0
[root@node01 ~]# curl 10.0.0.223
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

headless方式

因为pod数量的伸缩，Pod的地址是经常变化的，所以绑定DNS访问设置clusterIP为none

[root@master demo]# vim headless.yaml
apiVersion: v1
kind: Service
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: nginx
我们看到nginx的CLUSTER-IP为None
[root@master demo]# kubectl get svc
NAME            TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
kubernetes      ClusterIP   10.0.0.1     <none>        443/TCP        15d
nginx           ClusterIP   None         <none>        80/TCP         21s
nginx-service   NodePort    10.0.0.223   <none>        80:42524/TCP   16m

绑定DNS https://www.kubernetes.org.cn/4694.html

将coredns.yaml文件放到master的家目录下

[root@master ~]# kubectl create -f coredns.yaml
serviceaccount/coredns created
clusterrole.rbac.authorization.k8s.io/system:coredns created
clusterrolebinding.rbac.authorization.k8s.io/system:coredns created
configmap/coredns created
deployment.extensions/coredns created
service/kube-dns created
[root@master ~]# kubectl get pods -n kube-system
NAME                                    READY   STATUS    RESTARTS   AGE
coredns-56684f94d6-85j72                1/1     Running   0          2m41s
kubernetes-dashboard-7dffbccd68-kvlqd   1/1     Running   1          2d17h

创建一个资源来，验证下dns解析功能

[root@master demo]# vim pod3.yaml
apiVersion: v1
kind: Pod
metadata:
  name: dns-test
spec:
  containers:
  - name: busybox
    image: busybox:1.28.4
    args:
    - /bin/sh
    - -c
    - sleep 36000
  restartPolicy: Never
[root@master demo]# kubectl create -f pod3.yaml
pod/dns-test created
[root@master demo]# kubectl get svc
NAME            TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
kubernetes      ClusterIP   10.0.0.1     <none>        443/TCP        15d
nginx           ClusterIP   None         <none>        80/TCP         30m
nginx-service   NodePort    10.0.0.223   <none>        80:42524/TCP   46m

验证解析

[root@master demo]# kubectl exec -it dns-test sh
/ # nslookup kubernetes
Server:    10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes
Address 1: 10.0.0.1 kubernetes.default.svc.cluster.local
/ # nslookup nginx-service
Server:    10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local

Name:      nginx-service
Address 1: 10.0.0.223 nginx-service.default.svc.cluster.local

清理下master上的资源

[root@master demo]# kubectl delete -f .

重新创建资源，来使用DNS解析pod的ip

[root@master demo]# vim sts.yaml
apiVersion: v1
kind: Service
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: nginx
---
apiVersion: apps/v1beta1  
kind: StatefulSet  
metadata:
  name: nginx-statefulset  
  namespace: default
spec:
  serviceName: nginx  
  replicas: 3  
  selector:
    matchLabels:  
       app: nginx
  template:  
    metadata:
      labels:
        app: nginx  
    spec:
      containers:
      - name: nginx
        image: nginx:latest  
        ports:
        - containerPort: 80

创建资源

[root@master demo]# kubectl create -f sts.yaml
[root@master demo]# kubectl create -f /root/coredns.yaml
[root@master demo]# kubectl get pods
NAME                      READY   STATUS    RESTARTS   AGE
pod/dns-test              1/1     Running   0          44m
pod/nginx-statefulset-0   1/1     Running   0          46m
pod/nginx-statefulset-1   1/1     Running   0          46m
pod/nginx-statefulset-2   1/1     Running   0          45m

[root@master demo]# kubectl apply -f pod3.yaml
pod/dns-test created
[root@master demo]# kubectl get pods -o wide
NAME                  READY   STATUS    RESTARTS   AGE     IP            NODE        NOMINATED NODE
dns-test              1/1     Running   0          7m31s   172.17.47.3   20.0.0.40   <none>
nginx-statefulset-0   1/1     Running   0          9m1s    172.17.47.2   20.0.0.40   <none>
nginx-statefulset-1   1/1     Running   0          8m44s   172.17.3.2    20.0.0.30   <none>
nginx-statefulset-2   1/1     Running   0          8m22s   172.17.3.3    20.0.0.30   <none>

如果解析不出来，就把dns重新创一遍，kubectl delete -f coredns.yaml 然后kubectl create -f coredns.yaml

[root@master demo]# kubectl exec -it dns-test sh

/ # nslookup nginx-statefulset-0.nginx
Server:    10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local

Name:      nginx-statefulset-0.nginx
Address 1: 172.17.47.2 nginx-statefulset-0.nginx.default.svc.cluster.local
/ # nslookup nginx-statefulset-1.nginx
Server:    10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local

Name:      nginx-statefulset-1.nginx
Address 1: 172.17.3.2 nginx-statefulset-1.nginx.default.svc.cluster.local
/ # nslookup nginx-statefulset-2.nginx
Server:    10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local

Name:      nginx-statefulset-2.nginx
Address 1: 172.17.3.3 nginx-statefulset-2.nginx.default.svc.cluster.local

k8s配置管理

k8s中的配置管理，可用在引用参数、挂载准备好的文件，可用在需要修改大量配置文件的场景中

Secret

加密数据并存放在etcd中，让pod容器以挂载volume方式访问应用场景：凭据生成secret方式一：

[root@master demo]# echo -n 'admin' > ./username.txt
[root@master demo]# echo -n '123456' > ./password.txt
[root@master demo]# kubectl create secret generic db-user-pass --from-file=./username.txt --from-file=./password.txt
secret/db-user-pass created
[root@master demo]# kubectl get secret
NAME                  TYPE                                  DATA   AGE
db-user-pass          Opaque                                2      10s
default-token-cscgs   kubernetes.io/service-account-token   3      16d
[root@master demo]# kubectl describe secret db-user-pass
Name:         db-user-pass
Namespace:    default
Labels:       <none>
Annotations:  <none>

Type:  Opaque

Data
====
password.txt:  6 bytes
username.txt:  5 bytes

生成secret文件方式二：

[root@master demo]# vim secret-var.yaml
apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
  - name: nginx
    image: nginx
    env:
      - name: SECRET_USERNAME
        valueFrom:
          secretKeyRef:
            name: mysecret
            key: username
      - name: SECRET_PASSWORD
        valueFrom:
          secretKeyRef:
            name: mysecret
            key: password

我们可以将secret类型文件中的参数传递到pod中其中env下就是设置一些环境变量，变量名SECRET_USERNAME和SECRET_PASSWORD，变量的值的来源是mysecret中的username和password 创建相应Pod,相应变量和值就被传递到了其中

[root@master demo]# kubectl apply -f secret-var.yaml
pod/mypod created
[root@master demo]# kubectl exec -it mypod bash
root@mypod:/# echo $SECRET-USERNAME
-USERNAME
root@mypod:/# echo $SECRET_USERNAME
admin
root@mypod:/# echo $SECRET_PASSWORD
123456

挂载文件

[root@master demo]# vim secret-vol.yaml
apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
  - name: nginx
    image: nginx
    volumeMounts:
    - name: foo
      mountPath: "/etc/foo"
      readOnly: true
  volumes:
  - name: foo
    secret:
      secretName: mysecret

其中volumes下是被挂载的卷mysecret并命名成foo，需要挂载只要使用这个名字即可 volumeMounts是挂载，挂载路径在/etc/foo

[root@master demo]# kubectl delete -f secret-var.yaml
pod "mypod" deleted
[root@master demo]# kubectl create -f secret-vol.yaml
pod/mypod created
[root@master demo]# kubectl get pods
NAME                  READY   STATUS    RESTARTS   AGE
dns-test              1/1     Running   0          7h40m
mypod                 1/1     Running   0          18s
nginx-statefulset-0   1/1     Running   0          7h41m
nginx-statefulset-1   1/1     Running   0          7h41m
nginx-statefulset-2   1/1     Running   0          7h40m

进入容器中查看挂载

[root@master demo]# kubectl exec -it mypod bash
root@mypod:/# ls /etc/fo
fonts/ foo/   
root@mypod:/# ls /etc/fo
fonts/ foo/   
root@mypod:/# ls /etc/foo/
password  username
root@mypod:/# cd /etc/foo/
root@mypod:/etc/foo# cat password
123456root@mypod:/etc/foo# cat username
adminroot@mypod:/etc/foo#

ConfigMap

与secret类似，区别在于ConfigMap保存的是不需要加密的配置信息应用场景：应用配置

[root@master demo]# vim redis.properties
redis.host=127.0.0.1
redis.port=6379
redis.password=123456

[root@master demo]# kubectl create configmap redis-confg --from-file=redis.properties
configmap/redis-confg created
[root@master demo]# kubectl get configmap
NAME          DATA   AGE
redis-confg   1      10s

[root@master demo]# kubectl describe cm redis-confg
Name:         redis-confg
Namespace:    default
Labels:       <none>
Annotations:  <none>

Data
====
redis.properties:
----
redis.host=127.0.0.1
redis.port=6379
redis.password=123456

Events:  <none>

变量参数创建configmap资源

[root@master demo]# vim myconfig.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: myconfig
  namespace: default
data:
  special.level: info
  special.type: hello
[root@master demo]# kubectl apply -f myconfig.yaml
configmap/myconfig created
[root@master demo]# vim config-var.yaml
apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
    - name: busybox
      image: busybox
      command: [ "/bin/sh", "-c", "echo $(LEVEL) $(TYPE)" ]
      env:
        - name: LEVEL
          valueFrom:
            configMapKeyRef:
              name: myconfig
              key: special.level
        - name: TYPE
          valueFrom:
            configMapKeyRef:
              name: myconfig
              key: special.type
  restartPolicy: Never

其中创建容器并输出两个变量的值，LEVEL来源myconfig文件中的special.level，TYPE来自myconfig中的special.type 删除之前创建的资源

[root@master demo]# kubectl delete pod mypod

创建资源

[root@master demo]# kubectl create -f config-var.yaml
pod/mypod created
[root@master demo]# kubectl get pods
NAME                  READY   STATUS      RESTARTS   AGE
dns-test              1/1     Running     0          8h
mypod                 0/1     Completed   0          30s

查看变量输出

[root@master demo]# kubectl logs mypod
info hello

资讯详情

k8s调度约束、控制器、无头服务和配置管理

文章目录

调度方式

nodeName方式

nodeSelect方式

故障排除

控制器

Deployment

SatefulSet

DaemonSet

Job

CronJob

常规service和无头服务区别

service

headless方式

k8s配置管理

Secret

ConfigMap

C++中用memcpy()函数复制字符串的正确方法

k8s调度约束、控制器、无头服务和配置管理

文章目录

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