一.基本概念
由于Pod和Service是kubernetes集群范围内的虚拟概念，所以集群外的客户端系统无法通过Pod的IP地址或者Service的虚拟IP地址和虚拟端口号访问到它们。为了让外部客户端能够访问到这些服务，可以将Pod或Service的端口号映射到宿主机。
1.将容器应用的端口号映射到物理机
1）设置容器级别的hostPort，将容器应用的端口号映射到物理机
2）设置Pod级别的hostNetwork=true，该Pod中所有容器的端口号都将被直接映射到物理机上
2.将Service的端口号映射到物理机
1）设置nodePort映射到物理机，同时设置Service的类型为NodePort
2）设置LoadBalancer映射到云服务商提供的LoadBalancer地址
如果设置了Service的nodePort，那么集群会在每一个节点都监听设置的nodePort，外部客户端可以通过任意nodeIP:Port的方式对集群服务进行访问。但是当集群中服务较多，那么需要管理的端口也会比较多，各个端口之间不能冲突，比较麻烦；另外，因为方式访问形式为nodeIP:Port的方式，那么对于一些HTTP服务，这种方式是无法做到根据URL路径进行转发的。ingress是kubernetes V1.1版本之后新增的资源对象，用于实现HTTP层业务路由机制。
实现ingress路由机制主要包括3个组件：
1）ingress是kubernetes的一个资源对象，用于编写定义规则
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2）反向代理负载均衡器，通常以Service的Port方式运行，接收并按照ingress定义的规则进行转发，通常为nginx，haproxy，traefik等，本文使用nginx
3）ingress-controller，监听apiserver，获取服务新增，删除等变化，并结合ingress规则动态更新到反向代理负载均衡器上，并重载配置使其生效
二.部署
本文使用谷歌提供的nginx-ingress-controller镜像创建ingress-controller，并以Pod+Service方式运行，其中Service使用nodePort方式将80,443端口映射至物理机上
部署过程中使用到的文档参考：https://github.com/kubernetes/ingress-nginx/tree/master/deploy
1.下载各所需的yaml文件
curl https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/namespace.yaml >namespace.yaml curl https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/default-backend.yaml>default-backend.yaml curl https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/configmap.yaml>configmap.yaml curl https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/tcp-services-configmap.yaml>tcp-services-configmap.yaml curl https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/udp-services-configmap.yaml > udp-services-configmap.yaml curl https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/without-rbac.yaml>without-rbac.yaml curl https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/rbac.yaml>rbac.yaml curl https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/with-rbac.yaml > with-rbac.yaml curl https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/provider/baremetal/service-nodeport.yaml >service-nodeport.yaml
2.启动上述yaml文件
kubectl create -f namespace.yaml kubectl create -f configmap.yaml kubectl create -f default-backend.yaml kubectl create -f tcp-services-configmap.yaml kubectl create -f udp-services-configmap.yaml kubectl create -f rbac.yaml kubectl create -f with-rbac.yaml kubectl create -f service-nodeport.yaml
上述yaml文件中几乎可以不用修改，仅default-backend.yaml以及with-rbac.yaml两个文件需要简单修改。
default-backend.yaml文件定义了默认的ingress服务，即客户端访问的URL地址不存在时，默认返回的页面，这个服务使用任何应用实现都可以，只需要能够返回一个404应答，并且提供/healthz路径实现健康检查，另外服务名称需要设置为default-backend-service，因为该镜像中nginx默认通过default-backend-service访问默认backend
rabc.yaml是kubernetes实现鉴权的方式，本文不做介绍
with-rbac.yaml文件中定义了一个Deployment，运行ingress-controller；需要注意的是如果修改了yaml文件中使用的镜像，部分参数可能需要更改，这个具体情况具体分析，本文不做说明
service-nodeport.yaml文件定义了一个服务，并且以nodePort方式监听80以及443端口，为客户端提供访问入口。
上述文件修改后如下：
nginx-ingress]# cat namespace.yaml apiVersion: v1 kind: Namespace metadata: name: ingress-nginx ############################ nginx-ingress]# cat configmap.yaml kind: ConfigMap apiVersion: v1 metadata: name: nginx-configuration namespace: ingress-nginx labels: app: ingress-nginx ############################## nginx-ingress]# cat rbac.yaml apiVersion: v1 kind: ServiceAccount metadata: name: nginx-ingress-serviceaccount namespace: ingress-nginx --- apiVersion: rbac.authorization.k8s.io/v1beta1 kind: ClusterRole metadata: name: nginx-ingress-clusterrole rules: - apiGroups: - "" resources: - configmaps - endpoints - nodes - pods - secrets verbs: - list - watch - apiGroups: - "" resources: - nodes verbs: - get - apiGroups: - "" resources: - services verbs: - get - list - watch - apiGroups: - "extensions" resources: - ingresses verbs: - get - list - watch - apiGroups: - "" resources: - events verbs: - create - patch - apiGroups: - "extensions" resources: - ingresses/status verbs: - update --- apiVersion: rbac.authorization.k8s.io/v1beta1 kind: Role metadata: name: nginx-ingress-role namespace: ingress-nginx rules: - apiGroups: - "" resources: - configmaps - pods - secrets - namespaces verbs: - get - apiGroups: - "" resources: - configmaps resourceNames: # Defaults to "<election-id>-<ingress-class>" # Here: "<ingress-controller-leader>-<nginx>" # This has to be adapted if you change either parameter # when launching the nginx-ingress-controller. - "ingress-controller-leader-nginx" verbs: - get - update - apiGroups: - "" resources: - configmaps verbs: - create - apiGroups: - "" resources: - endpoints verbs: - get - create - update --- apiVersion: rbac.authorization.k8s.io/v1beta1 kind: RoleBinding metadata: name: nginx-ingress-role-nisa-binding namespace: ingress-nginx roleRef: apiGroup: rbac.authorization.k8s.io kind: Role name: nginx-ingress-role subjects: - kind: ServiceAccount name: nginx-ingress-serviceaccount namespace: ingress-nginx --- apiVersion: rbac.authorization.k8s.io/v1beta1 kind: ClusterRoleBinding metadata: name: nginx-ingress-clusterrole-nisa-binding roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: nginx-ingress-clusterrole subjects: - kind: ServiceAccount name: nginx-ingress-serviceaccount namespace: ingress-nginx ############################# nginx-ingress]# cat tcp-services-configmap.yaml kind: ConfigMap apiVersion: v1 metadata: name: tcp-services namespace: ingress-nginx ############################# nginx-ingress]# cat udp-services-configmap.yaml kind: ConfigMap apiVersion: v1 metadata: name: udp-services namespace: ingress-nginx ############################# nginx-ingress]# cat service-nodeport.yaml apiVersion: v1 kind: Service metadata: name: ingress-nginx namespace: ingress-nginx spec: type: NodePort ports: - name: http port: 80 targetPort: 80 nodePort: 80 protocol: TCP - name: https port: 443 targetPort: 443 nodePort: 443 protocol: TCP selector: app: ingress-nginx ############################## nginx-ingress]# cat default-backend.yaml apiVersion: extensions/v1beta1 kind: Deployment metadata: name: default-http-backend labels: app: default-http-backend namespace: ingress-nginx spec: replicas: 1 selector: matchLabels: app: default-http-backend template: metadata: labels: app: default-http-backend spec: terminationGracePeriodSeconds: 60 containers: - name: default-http-backend # Any image is permissible as long as: # 1. It serves a 404 page at / # 2. It serves 200 on a /healthz endpoint #image: gcr.io/google_containers/defaultbackend:1.4 image: index.tenxcloud.com/google_containers/defaultbackend:1.0 livenessProbe: httpGet: path: /healthz port: 8080 scheme: HTTP initialDelaySeconds: 30 timeoutSeconds: 5 ports: - containerPort: 8080 resources: limits: cpu: 10m memory: 20Mi requests: cpu: 10m memory: 20Mi --- apiVersion: v1 kind: Service metadata: name: default-http-backend namespace: ingress-nginx labels: app: default-http-backend spec: ports: - port: 80 targetPort: 8080 selector: app: default-http-backend #################################### nginx-ingress]# cat with-rbac.yaml apiVersion: extensions/v1beta1 kind: Deployment metadata: name: nginx-ingress-controller namespace: ingress-nginx spec: replicas: 1 selector: matchLabels: app: ingress-nginx template: metadata: labels: app: ingress-nginx annotations: prometheus.io/port: '10254' prometheus.io/scrape: 'true' spec: serviceAccountName: nginx-ingress-serviceaccount containers: - name: nginx-ingress-controller #image: quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.15.0 #image: gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.2 image: index.tenxcloud.com/google_containers/nginx-ingress-controller:0.8.3 args: - /nginx-ingress-controller - --default-backend-service=$(POD_NAMESPACE)/default-http-backend - --nginx-configmap=$(POD_NAMESPACE)/nginx-configuration - --tcp-services-configmap=$(POD_NAMESPACE)/tcp-services - --udp-services-configmap=$(POD_NAMESPACE)/udp-services #- --annotations-prefix=nginx.ingress.kubernetes.io env: - name: POD_NAME valueFrom: fieldRef: fieldPath: metadata.name - name: POD_NAMESPACE valueFrom: fieldRef: fieldPath: metadata.namespace ports: - name: http containerPort: 80 - name: https containerPort: 443 livenessProbe: failureThreshold: 3 httpGet: path: /healthz port: 10254 scheme: HTTP initialDelaySeconds: 10 periodSeconds: 10 successThreshold: 1 timeoutSeconds: 1 readinessProbe: failureThreshold: 3 httpGet: path: /healthz port: 10254 scheme: HTTP periodSeconds: 10 successThreshold: 1 timeoutSeconds: 1 securityContext: runAsNonRoot: false
三，ingress规则编写
下面是一个简单的例子
nginx-ingress]# cat mytest.yaml apiVersion: extensions/v1beta1 kind: Ingress metadata: name: test-ingress annotations: ingress.kubernetes.io/ssl-redirect: "false" ##关闭强制使用HTTPS的设置 spec: rules: ## 根据URL路径实现转发，域名为 * - http: paths: - path: /demo backend: serviceName: mydemo servicePort: 8080 - path: /test backend: serviceName: mytest servicePort: 8080 nginx-ingress]# cat mytest.yaml apiVersion: extensions/v1beta1 kind: Ingress metadata: name: pand-ingress annotations: ingress.kubernetes.io/ssl-redirect: "false" spec: rules: ## 根据域名实现转发 - host: www.mywebsite1.com http: paths: - backend: serviceName: mydemo servicePort: 8080 - host: www.mywebsite2.com http: paths: - backend: serviceName: mytest servicePort: 8080
创建上述ingress，在客户端配置好域名解析，实现访问