一、Ingress 简介
在Kubernetes中，服务和Pod的IP地址仅可以在集群网络内部使用，对于集群外的应用是不可见的。为了使外部的应用能够访问集群内的服务，在Kubernetes 目前 提供了以下几种方案：
NodePort
LoadBalancer
Ingress

Ingress 组成
ingress controller
　　将新加入的Ingress转化成Nginx的配置文件并使之生效
ingress服务
　　将Nginx的配置抽象成一个Ingress对象，每添加一个新的服务只需写一个新的Ingress的yaml文件即可


Ingress 工作原理
1.ingress controller通过和kubernetes api交互，动态的去感知集群中ingress规则变化，
2.然后读取它，按照自定义的规则，规则就是写明了哪个域名对应哪个service，生成一段nginx配置，
3.再写到nginx-ingress-control的pod里，这个Ingress controller的pod里运行着一个Nginx服务，控制器会把生成的nginx配置写入/etc/nginx.conf文件中，
4.然后reload一下使配置生效。以此达到域名分配置和动态更新的问题。
Ingress 可以解决什么问题
1.动态配置服务
　　如果按照传统方式, 当新增加一个服务时, 我们可能需要在流量入口加一个反向代理指向我们新的k8s服务. 而如果用了Ingress, 只需要配置好这个服务, 当服务启动时, 会自动注册到Ingress的中, 不需要而外的操作.
2.减少不必要的端口暴露
　　配置过k8s的都清楚, 第一步是要关闭防火墙的, 主要原因是k8s的很多服务会以NodePort方式映射出去, 这样就相当于给宿主机打了很多孔, 既不安全也不优雅. 而Ingress可以避免这个问题, 除了Ingress自身服务可能需要映射出去, 其他服务都不要用NodePort方式

 

二、部署配置Ingress

1 .部署文件介绍、准备

获取配置文件位置: https://github.com/kubernetes/ingress-nginx/tree/nginx-0.20.0/deploy

下载部署文件

提供了两种方式 ：
　　默认下载最新的yaml：
　　　　wget  https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/mandatory.yaml
　　指定版本号下载对应的yaml 
　　　　

 部署文件介绍

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1.namespace.yaml 
创建一个独立的命名空间 ingress-nginx

2.configmap.yaml 
ConfigMap是存储通用的配置变量的，类似于配置文件，使用户可以将分布式系统中用于不同模块的环境变量统一到一个对象中管理；而它与配置文件的区别在于它是存在集群的“环境”中的，并且支持K8S集群中所有通用的操作调用方式。
从数据角度来看，ConfigMap的类型只是键值组，用于存储被Pod或者其他资源对象（如RC）访问的信息。这与secret的设计理念有异曲同工之妙，主要区别在于ConfigMap通常不用于存储敏感信息，而只存储简单的文本信息。
ConfigMap可以保存环境变量的属性，也可以保存配置文件。
创建pod时，对configmap进行绑定，pod内的应用可以直接引用ConfigMap的配置。相当于configmap为应用/运行环境封装配置。
pod使用ConfigMap，通常用于：设置环境变量的值、设置命令行参数、创建配置文件。

3.default-backend.yaml 
如果外界访问的域名不存在的话，则默认转发到default-http-backend这个Service，其会直接返回404：

4.rbac.yaml 
负责Ingress的RBAC授权的控制，其创建了Ingress用到的ServiceAccount、ClusterRole、Role、RoleBinding、ClusterRoleBinding

5.with-rbac.yaml 
是Ingress的核心，用于创建ingress-controller。前面提到过，ingress-controller的作用是将新加入的Ingress进行转化为Nginx的配置
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2.部署ingress

准备镜像，从这里mandatory.yaml查看需要哪些镜像

镜像名称版本下载地址
k8s.gcr.io/defaultbackend-amd64 1.5 registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/defaultbackend-amd64
quay.io/kubernetes-ingress-controller/nginx-ingress-controller 0.20.0 registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/nginx-ingress-controller

在每一个节点(Node)上下载镜像:

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[root@k8s-node1 ~]# docker pull registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/defaultbackend-amd64:1.5  #注意版本号
Trying to pull repository registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/defaultbackend-amd64 ... 
1.5: Pulling from registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/defaultbackend-amd64
26de8f6c1f4b: Pull complete 
Digest: sha256:2cdff48ab9b20ca5f9b0ee48bf3c139c51d6fb1a15245966583bc371c121c238
Status: Downloaded newer image for registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/defaultbackend-amd64:1.5
[root@k8s-node1 ~]#  docker pull registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/nginx-ingress-controller:0.20.0 #注意版本号
Trying to pull repository registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/nginx-ingress-controller ... 
0.20.0: Pulling from registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/nginx-ingress-controller
8e41b996a802: Pull complete 
f8e7d603ef88: Pull complete 
610da4f3123f: Pull complete 
62702a85e6c9: Pull complete 
7cedf5b2083f: Pull complete 
755f7fa719b6: Pull complete 
6adbdd0c8aaf: Pull complete 
2389d8b0d2a2: Pull complete 
1ea794448393: Pull complete 
bb0c388ee432: Pull complete 
9626641c5a97: Pull complete 
bd0bebb5ba38: Pull complete 
Digest: sha256:3f06079f7727b2fb7ad5c97d8152eb622ae504674395dfa71fda7ce315aaaf30
Status: Downloaded newer image for registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/nginx-ingress-controller:0.20.0
[root@k8s-node1 ~]# docker images  #检查镜像是否下载成功
REPOSITORY                                                                    TAG                 IMAGE ID            CREATED             SIZE
registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/defaultbackend-amd64       1.5                 d8f37b8cdaf4        2 weeks ago         5.13 MB
registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/nginx-ingress-controller   0.20.0              3cc332ecde4f        3 weeks ago         513 MB
k8s.gcr.io/kube-proxy-amd64                                                   v1.10.0             bfc21aadc7d3        7 months ago        97 MB
k8s.gcr.io/kube-controller-manager-amd64                                      v1.10.0             ad86dbed1555        7 months ago        148 MB
k8s.gcr.io/kube-scheduler-amd64                                               v1.10.0             704ba848e69a        7 months ago        50.4 MB
k8s.gcr.io/kube-apiserver-amd64                                               v1.10.0             af20925d51a3        7 months ago        225 MB
k8s.gcr.io/etcd-amd64                                                         3.1.12              52920ad46f5b        8 months ago        193 MB
k8s.gcr.io/kubernetes-dashboard-amd64                                         v1.8.3              0c60bcf89900        8 months ago        102 MB
quay.io/coreos/flannel                                                        v0.10.0-amd64       f0fad859c909        9 months ago        44.6 MB
k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64                                        1.14.8              c2ce1ffb51ed        10 months ago       41 MB
k8s.gcr.io/k8s-dns-sidecar-amd64                                              1.14.8              6f7f2dc7fab5        10 months ago       42.2 MB
k8s.gcr.io/k8s-dns-kube-dns-amd64                                             1.14.8              80cc5ea4b547        10 months ago       50.5 MB
k8s.gcr.io/pause-amd64                                                        3.1                 da86e6ba6ca1        10 months ago       742 kB
docker.io/kubeguide/tomcat-app                                                v1                  a29e200a18e9        2 years ago         358 MB
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下载yaml文件并更新mandatory.yaml中的镜像地址（master上）

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[root@k8s-master ~]# mkdir ingress-nginx
[root@k8s-master ingress-nginx]# wget  https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.20.0/deploy/mandatory.yaml
[root@k8s-master ingress-nginx]# wget  https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.20.0/deploy/provider/baremetal/service-nodeport.yaml      #对外提供服务，如果不需要可以不下载
[root@k8s-master ingress-nginx]# sed -i 's#k8s.gcr.io/defaultbackend-amd64#registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/defaultbackend-amd64#g' mandatory.yaml  #替换defaultbackend-amd64镜像地址
 sed -i 's#quay.io/kubernetes-ingress-controller/nginx-ingress-controller#registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/nginx-ingress-controller#g' mandatory.yaml  #替换nginx-ingress-controller镜像地址
[root@k8s-master ingress-nginx]# grep image mandatory.yaml   #检查替换结果
          # Any image is permissible as long as:
          image: registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/defaultbackend-amd64:1.5
          image: registry.cn-qingdao.aliyuncs.com/kubernetes_xingej/nginx-ingress-controller:0.20.0
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修改service-nodeport.yaml文件，添加NodePort端口，默认为随机端口

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[root@k8s-master ingress-nginx]# cat service-nodeport.yaml
apiVersion: v1
kind: Service
metadata:
  name: ingress-nginx
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  type: NodePort
  ports:
    - name: http
      port: 80
      targetPort: 80
      protocol: TCP
      nodePort: 32080  #http
    - name: https
      port: 443
      targetPort: 443
      protocol: TCP
      nodePort: 32443  #https
  selector:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
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部署nginx-ingress-controller

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[root@k8s-master ingress-nginx]# kubectl apply -f mandatory.yaml 
namespace "ingress-nginx" created
deployment.extensions "default-http-backend" created
service "default-http-backend" created
configmap "nginx-configuration" created
configmap "tcp-services" created
configmap "udp-services" created
serviceaccount "nginx-ingress-serviceaccount" created
clusterrole.rbac.authorization.k8s.io "nginx-ingress-clusterrole" created
role.rbac.authorization.k8s.io "nginx-ingress-role" created
rolebinding.rbac.authorization.k8s.io "nginx-ingress-role-nisa-binding" created
clusterrolebinding.rbac.authorization.k8s.io "nginx-ingress-clusterrole-nisa-binding" created
deployment.extensions "nginx-ingress-controller" created
[root@k8s-master ingress-nginx]# kubectl apply -f service-nodeport.yaml 
service "ingress-nginx" created
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3.查看ingress-nginx组件状态

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[root@k8s-master ingress-nginx]#  kubectl get pods -n ingress-nginx    #pod状态
NAME                                        READY     STATUS    RESTARTS   AGE
default-http-backend-66c4fbf5b4-x2n8w       1/1       Running   0          58s
nginx-ingress-controller-64bcff8657-5gdrd   1/1       Running   0          58s
[root@k8s-master ingress-nginx]#  kubectl get svc -n ingress-nginx  #service状态及暴露端口
NAME                   TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)                      AGE
default-http-backend   ClusterIP   10.96.87.65     <none>        80/TCP                       1m
ingress-nginx          NodePort    10.100.48.237   <none>        80:32080/TCP,443:32443/TCP   1m
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4.访问ingress-nginx服务，查看是否配置成功

可以看到，提示404，这个因为当前ingress-nginx服务现在还没有后端服务，这是正常的

三、创建ingress-nginx后端服务

1.创建一个Service及后端Deployment(以nginx为例)

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[root@k8s-master01 ingress]# cat deploy-demon.yaml 
apiVersion: v1
kind: Service
metadata:
  name: myapp
  namespace: default
spec:
  selector:
    app: myapp
    release: canary
  ports:
  - name: http
    port: 80
    targetPort: 80
---
apiVersion: apps/v1
kind: Deployment
metadata: 
  name: myapp-deploy
spec:
  replicas: 5
  selector: 
    matchLabels:
      app: myapp
      release: canary
  template:
    metadata:
      labels:
        app: myapp
        release: canary
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v2
        ports:
        - name: httpd
          containerPort: 80
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创建相关服务及检查状态是否就绪

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[root@k8s-master ingress-nginx]# kubectl apply -f deploy-demon.yaml 
service "myapp" created
deployment.apps "myapp-deploy" created
[root@k8s-master ingress-nginx]# kubectl get pods
NAME                            READY     STATUS    RESTARTS   AGE
myapp-deploy-5cfd895984-ffzm5   1/1       Running   0          1m
myapp-deploy-5cfd895984-ftg9t   1/1       Running   0          1m
myapp-deploy-5cfd895984-jg887   1/1       Running   0          1m
myapp-deploy-5cfd895984-mk4jq   1/1       Running   0          1m
myapp-deploy-5cfd895984-nqz6s   1/1       Running   0          1m
myweb-hrfqm                     1/1       Running   0          8d
myweb-pb5tb                     1/1       Running   0          8d
myweb-xrk22                     1/1       Running   0          8d
[root@k8s-master ingress-nginx]# kubectl get svc
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE
kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP          9d
myapp        ClusterIP   10.102.30.215    <none>        80/TCP           1m
myweb        NodePort    10.106.138.244   <none>        8080:31888/TCP   8d
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将myapp添加至ingress-nginx中

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[root@k8s-master ingress-nginx]# cat ingress-myapp.yaml 
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-myapp
  namespace: default
  annotations: 
    kubernetes.io/ingress.class: "nginx"
spec:
  rules:
  - host: myapp.magedu.com #生产中该域名应当可以被公网解析
    http:
      paths:
      - path: 
        backend:
          serviceName: myapp
          servicePort: 80

[root@k8s-master ingress-nginx]# kubectl apply -f ingress-myapp.yaml  
ingress.extensions "ingress-myapp" created

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配置域名解析，当前测试环境我们使用hosts文件进行解析

172.33.16.241  myapp.magedu.com

使用域名进行访问

2.再创建一个Service及后端Deployment(以tomcat为例)

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[root@k8s-master ingress-nginx]# cat tomcat-deploy.yaml 
apiVersion: v1
kind: Service
metadata:
  name: tomcat
  namespace: default
spec:
  selector:
    app: tomcat
    release: canary
  ports:
  - name: http
    port: 8080
    targetPort: 8080
  - name: ajp
    port: 8009
    targetPort: 8009

---
apiVersion: apps/v1
kind: Deployment
metadata: 
  name: tomcat-deploy
spec:
  replicas: 3
  selector: 
    matchLabels:
      app: tomcat
      release: canary
  template:
    metadata:
      labels:
        app: tomcat
        release: canary
    spec:
      containers:
      - name: tomcat
        image: tomcat:7-alpine
        ports:
        - name: httpd
          containerPort: 8080
        - name: ajp
          containerPort: 8009 
[root@k8s-master ingress-nginx]# kubectl apply -f tomcat-deploy.yaml 
service "tomcat" created
deployment.apps "tomcat-deploy" created
[root@k8s-master ingress-nginx]# kubectl get pod #等待pod状态就绪
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将tomcat添加至ingress-nginx中

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[root@k8s-master ingress-nginx]# cat ingress-tomcat.yaml 
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-tomcat
  namespace: default
  annotations: 
    kubernets.io/ingress.class: "nginx"
spec:
  rules:
  - host: tomcat.magedu.com
    http:
      paths:
      - path: 
        backend:
          serviceName: tomcat
          servicePort: 8080
[root@k8s-master ingress-nginx]# kubectl apply -f ingress-tomcat.yaml 
ingress.extensions "ingress-tomcat" created
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添加域名解析及访问服务

 

3.下面我们对tomcat服务添加httpds服务

创建私有证书及secret

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[root@k8s-master ingress-nginx]# openssl genrsa -out tls.key 2048
Generating RSA private key, 2048 bit long modulus
.......+++
..............................+++
e is 65537 (0x10001)
[root@k8s-master ingress-nginx]# openssl req -new -x509 -key tls.key -out tls.crt -subj /C=CN/ST=Beijing/L=Beijing/O=DevOps/CN=tomcat.magedu.com #注意域名要和服务的域名一致 
[root@k8s-master ingress-nginx]# kubectl create secret tls tomcat-ingress-secret --cert=tls.crt --key=tls.key #创建secret
secret "tomcat-ingress-secret" created
[root@k8s-master ingress-nginx]# kubectl get secret
NAME                    TYPE                                  DATA      AGE
default-token-bf52l     kubernetes.io/service-account-token   3         9d
tomcat-ingress-secret   kubernetes.io/tls                     2         7s
[root@k8s-master ingress-nginx]# kubectl describe secret tomcat-ingress-secret
Name:         tomcat-ingress-secret
Namespace:    default
Labels:       <none>
Annotations:  <none>

Type:  kubernetes.io/tls

Data
====
tls.crt:  1294 bytes  #base64加密
tls.key:  1679 bytes
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将证书应用至tomcat服务中

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[root@k8s-master01 ingress]# cat ingress-tomcat-tls.yaml
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-tomcat-tls
  namespace: default
  annotations: 
    kubernets.io/ingress.class: "nginx"
spec:
  tls:
  - hosts:
    - tomcat.magedu.com        #与secret证书的域名需要保持一致
    secretName: tomcat-ingress-secret   #secret证书的名称
  rules:
  - host: tomcat.magedu.com
    http:
      paths:
      - path: 
        backend:
          serviceName: tomcat
          servicePort: 8080
[root@k8s-master01 ingress]#  kubectl apply -f ingress-tomcat-tls.yaml
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访问服务

 

#参考文档：

参考博客：https://www.cnblogs.com/panwenbin-logs/p/9915927.html