• kubernetes，service详解下

    kubernetes，service详解下

    HeadLiness类型的Service

    在某些场景中，开发人员可能不想使用Service提供的负载均衡功能，而希望自己来控制负载均衡策略，针对这种情况，kubernetes提供了HeadLiness Service，这类Service不会分配Cluster IP，如果想要访问service，只能通过service的域名进行查询。
    在这里插入图片描述

    创建service-headliness.yaml

    
apiVersion: v1
kind: Service
metadata:
  name: service-headliness
  namespace: lh
spec:
  selector:
    app: nginx-pod
  clusterIP: None 
  type: ClusterIP
  ports:
  - port: 80    
    targetPort: 80


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    创建service,获取service， 发现CLUSTER-IP未分配

    

[root@master ~]# kubectl create -f service-headliness.yaml
service/service-headliness created
[root@master ~]# kubectl get svc service-headliness -n lh -o wide
NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE   SELECTOR
service-headliness   ClusterIP   None                 80/TCP    26s   app=nginx-pod


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    查看service详情

    

[root@master ~]# kubectl describe svc service-headliness -n lh
Name:              service-headliness
Namespace:         lh
Labels:            
Annotations:       
Selector:          app=nginx-pod
Type:              ClusterIP
IP Family Policy:  SingleStack
IP Families:       IPv4
IP:                None
IPs:               None
Port:                80/TCP
TargetPort:        80/TCP
Endpoints:         
Session Affinity:  None
Events:            


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    查看域名的解析情况

    [root@master ~]# kubectl exec -it pc-deployment-66cb59b984-8p84h -n lh /bin/sh
/ # cat /etc/resolv.conf
nameserver 10.96.0.10
search dev.svc.cluster.local svc.cluster.local cluster.local

[root@master ~]# dig @10.96.0.10 service-headliness.dev.svc.cluster.local
service-headliness.dev.svc.cluster.local. 30 IN A 10.244.1.40
service-headliness.dev.svc.cluster.local. 30 IN A 10.244.1.39
service-headliness.dev.svc.cluster.local. 30 IN A 10.244.2.33
//想要访问的话，需要在pod里面的容器进行访问，需要先运行一个pod起来，然后进入容器，进行访问
kubectl  run  busybox11 --image busybox  -n dev -- sleep 6000
kubectl  exec  -itn  dev -n dev busybox11 -- /bin/sh
//进入容器后，使用wget  -O - -q service-headliness就可以访问了


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    NodePort类型的Service

    在之前的样例中，创建的Service的ip地址只有集群内部才可以访问，如果希望将Service暴露给集群外部使用，那么就要使用到另外一种类型的Service，称为NodePort类型。NodePort的工作原理其实就是将service的端口映射到Node的一个端口上，然后就可以通过NodeIp:NodePort来访问service了。
    在这里插入图片描述

    创建service-nodeport.yaml

    
apiVersion: v1
kind: Service
metadata:
  name: service-nodeport
  namespace: lh
spec:
  selector:
    app: nginx-pod
  type: NodePort 
  ports:
  - port: 80
    nodePort: 30002
    targetPort: 80


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    创建service,并查看service

    
[root@master ~]# kubectl get svc -n lh -o wide
NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE   SELECTOR
service-headliness   ClusterIP   None                    80/TCP         18m   app=nginx-pod
service-nodeport     NodePort    10.110.136.75           80:30002/TCP   9s    app=nginx-pod



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    接下来可以通过电脑主机的浏览器去访问集群中任意一个nodeip的30002端口，即可访问到pod

    LoadBalancer类型的Service

    LoadBalancer和NodePort很相似，目的都是向外部暴露一个端口，区别在于LoadBalancer会在集群的外部再来做一个负载均衡设备，而这个设备需要外部环境支持的，外部服务发送到这个设备上的请求，会被设备负载之后转发到集群中。
    在这里插入图片描述

    ExternalName类型的Service

    ExternalName类型的Service用于引入集群外部的服务，它通过externalName属性指定外部一个服务的地址，然后在集群内部访问此service就可以访问到外部的服务了。
    在这里插入图片描述

    创建service-externalname.yaml文件

    

apiVersion: v1
kind: Service
metadata:
  name: service-externalname
  namespace: lh
spec:
  type: ExternalName 
  externalName: www.baidu.com 


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    创建service,域名解析

    [root@master ~]# kubectl create  -f service-externalname.yaml
service/service-externalname created
[root@master ~]# dig @10.96.0.10 service-externalname.dev.svc.cluster.local
service-externalname.dev.svc.cluster.local. 30 IN CNAME www.baidu.com.
www.baidu.com.          30      IN      CNAME   www.a.shifen.com.
www.a.shifen.com.       30      IN      A       39.156.66.18
www.a.shifen.com.       30      IN      A       39.156.66.14


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    Ingress介绍

    在上面已经提到，Service对集群之外暴露服务的主要方式有两种：NotePort和LoadBalancer，但是这两种方式，都有一定的缺点：
    • NodePort方式的缺点是会占用很多集群机器的端口，那么当集群服务变多的时候，这个缺点就愈发明显
    • LB方式的缺点是每个service需要一个LB，浪费、麻烦，并且需要kubernetes之外设备的支持
    基于这种现状，kubernetes提供了Ingress资源对象，Ingress只需要一个NodePort或者一个LB就可以满足暴露多个Service的需求。工作机制大致如下图表示：

    在这里插入图片描述

    实际上，Ingress相当于一个7层的负载均衡器，是kubernetes对反向代理的一个抽象，它的工作原理类似于Nginx，可以理解成在Ingress里建立诸多映射规则，Ingress Controller通过监听这些配置规则并转化成Nginx的反向代理配置 , 然后对外部提供服务。在这里有两个核心概念：
    • ingress：kubernetes中的一个对象，作用是定义请求如何转发到service的规则
    • ingress controller：具体实现反向代理及负载均衡的程序，对ingress定义的规则进行解析，根据配置的规则来实现请求转发，实现方式有很多，比如Nginx, Contour, Haproxy等等
    Ingress（以Nginx为例）的工作原理如下：

    1. 用户编写Ingress规则，说明哪个域名对应kubernetes集群中的哪个Service
    2. Ingress控制器动态感知Ingress服务规则的变化，然后生成一段对应的Nginx反向代理配置
    3. Ingress控制器会将生成的Nginx配置写入到一个运行着的Nginx服务中，并动态更新
    4. 到此为止，其实真正在工作的就是一个Nginx了，内部配置了用户定义的请求转发规则

    在这里插入图片描述

    Ingress使用

    环境准备
    搭建ingress环境
    创建文件夹

    
[root@master ~]# mkdir ingress-controller
[root@master ~]# cd ingress-controller/


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    在github官网上查找ingress对应的yaml文件并下载下来
    https://raw.githubusercontent.com/kubernetes/ingress-nginx/main/deploy/static/provider/baremetal/deploy.yaml

    [root@master ingress-controller]# wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/main/deploy/static/provider/baremetal/deploy.yaml


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    修改yaml内容

    
- name: LD_PRELOAD
          value: /usr/local/lib/libmimalloc.so
        image: dyrnq/ingress-nginx-controller:v1.5.1
        imagePullPolicy: IfNotPresent
        lifecycle:
 - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        image: lianyuxue1020/kube-webhook-certgen:v1.1.1
        imagePullPolicy: IfNotPresent
        name: create
        securityContext:
          allowPrivilegeEscalation: false

    - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        image: lianyuxue1020/kube-webhook-certgen:v1.1.1
        imagePullPolicy: IfNotPresent


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    应用

    
[root@master ingress-controller]# kubectl apply  -f deploy.yaml
namespace/ingress-nginx created
serviceaccount/ingress-nginx created
serviceaccount/ingress-nginx-admission created
role.rbac.authorization.k8s.io/ingress-nginx created
role.rbac.authorization.k8s.io/ingress-nginx-admission created
clusterrole.rbac.authorization.k8s.io/ingress-nginx created
clusterrole.rbac.authorization.k8s.io/ingress-nginx-admission created
rolebinding.rbac.authorization.k8s.io/ingress-nginx created
rolebinding.rbac.authorization.k8s.io/ingress-nginx-admission created
clusterrolebinding.rbac.authorization.k8s.io/ingress-nginx created
clusterrolebinding.rbac.authorization.k8s.io/ingress-nginx-admission created
configmap/ingress-nginx-controller created
service/ingress-nginx-controller created
service/ingress-nginx-controller-admission created
deployment.apps/ingress-nginx-controller created
job.batch/ingress-nginx-admission-create created
job.batch/ingress-nginx-admission-patch created
ingressclass.networking.k8s.io/nginx created
validatingwebhookconfiguration.admissionregistration.k8s.io/ingress-nginx-admission created


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    查看

    [root@master ingress-controller]# kubectl get svc -n ingress-nginx
NAME                                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                      AGE
ingress-nginx-controller             NodePort    10.104.199.252           80:31281/TCP,443:31750/TCP   73s
ingress-nginx-controller-admission   ClusterIP   10.108.255.10            443/TCP                      73s

[root@master ingress-controller]# kubectl get pod -n ingress-nginx
NAME                                        READY   STATUS      RESTARTS   AGE
ingress-nginx-admission-create-2nfhc        0/1     Completed   0          89s
ingress-nginx-admission-patch-r9l6r         0/1     Completed   1          89s
ingress-nginx-controller-6f66fd4bdb-mjf6g   1/1     Running     0          89s


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    准备service和pod
    为了后面的实验比较方便，创建如下图所示的模型
    在这里插入图片描述

    创建tomcat-nginx.yaml

    
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: lh
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1
        ports:
        - containerPort: 80
---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-deployment
  namespace: lh
spec:
  replicas: 3
  selector:
    matchLabels:
      app: tomcat-pod
  template:
    metadata:
      labels:
        app: tomcat-pod
    spec:
      containers:
      - name: tomcat
        image: tomcat:8.5-jre10-slim
        ports:
        - containerPort: 8080
---

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
  namespace: lh
spec:
  selector:
    app: nginx-pod
  clusterIP: None
  type: ClusterIP
  ports:
  - port: 80
    targetPort: 80
---

apiVersion: v1
kind: Service
metadata:
  name: tomcat-service
  namespace: lh
spec:
  selector:
    app: tomcat-pod
  clusterIP: None
  type: ClusterIP
  ports:
  - port: 8080
    targetPort: 8080


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    创建并查看

    
[root@master ingress-controller]# kubectl create -f tomcat-nginx.yaml
deployment.apps/nginx-deployment created
deployment.apps/tomcat-deployment created
service/nginx-service created
service/tomcat-service created
[root@master ingress-controller]# kubectl get svc -n lh
NAME                   TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)        AGE
nginx-service          ClusterIP      None                      80/TCP         10s

tomcat-service         ClusterIP      None                      8080/TCP       10s


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    Http代理

    创建ingress-http.yaml

    
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingress-http
  namespace: lh
spec:
  ingressClassName: nginx
  rules:
  - host: nginx.xuanning.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: nginx-service
            port: 
              number: 80
  - host: tomcat.xuanning.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: tomcat-service
            port: 
              number: 8080


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    创建并查看

    [root@master ingress-controller]# kubectl create -f ingress-http.yaml
ingress.networking.k8s.io/ingress-http created
[root@master ingress-controller]# kubectl get -f ingress-http.yaml
NAME           CLASS   HOSTS                                    ADDRESS   PORTS   AGE
ingress-http   nginx   nginx.xuanning.com,tomcat.xuanning.com             80      12s
[root@master ingress-controller]# kubectl describe ingress ingress-http -n lh
Name:             ingress-http
Labels:           
Namespace:        lh
Address:
Ingress Class:    nginx
Default backend:  
Rules:
  Host                 Path  Backends
  ----                 ----  --------
  nginx.xuanning.com
                       /   nginx-service:80 (10.244.1.7:80,10.244.2.61:80,10.244.2.62:80)
  tomcat.xuanning.com
                       /   tomcat-service:8080 (10.244.1.8:8080,10.244.1.9:8080,10.244.2.63:8080)




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    需要查看只需修改本地的host文件即可

    Https代理

    注意http和https只能定义一个，先删除http的
    创建证书

    生成证书

    [root@master ingress-controller]# openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:2048 -keyout tls.key -out tls.crt -subj "/C=CN/ST=BJ/L=BJ/O=nginx/CN=xuanning.com"



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    创建密钥

    
[root@master ingress-controller]# kubectl create secret tls tls-secret --key tls.key --cert tls.crt
secret/tls-secret created



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    创建ingress-https.yaml

    
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingress-https
  namespace: lh
spec:
  tls:
    - hosts:
      - nginx.xuanning.com
      - tomcat.xuanning.com
      secretName: tls-secret
  ingressClassName: nginx
  rules: 
  - host: nginx.xuanning.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service: 
            name: nginx-service
            port: 
              number: 80
  - host: tomcat.xuanning.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service: 
            name: tomcat-service
            port: 
              number: 8080


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    创建并查看

    

[root@master ingress-controller]# kubectl create -f ingress-https.yaml
ingress.networking.k8s.io/ingress-https created
[root@master ingress-controller]# kubectl get ing ingress-https -n lh
NAME            CLASS   HOSTS                                    ADDRESS   PORTS     AGE
ingress-https   nginx   nginx.xuanning.com,tomcat.xuanning.com             80, 443   9s
[root@master ingress-controller]#  kubectl describe ing ingress-https -n lh
Name:             ingress-https
Labels:           
Namespace:        lh
Address:
Ingress Class:    nginx
Default backend:  
TLS:
  tls-secret terminates nginx.xuanning.com,tomcat.xuanning.com
Rules:
  Host                 Path  Backends
  ----                 ----  --------
  nginx.xuanning.com
                       /   nginx-service:80 (10.244.1.7:80,10.244.2.61:80,10.244.2.62:80)
  tomcat.xuanning.com
                       /   tomcat-service:8080 (10.244.1.8:8080,10.244.1.9:8080,10.244.2.63:8080)


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    如需访问只要修改本地host文件即可

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  • 原文地址：https://blog.csdn.net/qq_45211528/article/details/128194317