外部服务发现-ingress

Ingress`其实就是从 kuberenets 集群外部访问集群的一个入口，将外部的请求转发到集群内不同的 Service 上，其实就相当于 nginx、haproxy 等负载均衡代理服务器,Ingress controller 可以理解为一个监听器，通过不断地与 kube-apiserver 打交道，实时的感知后端 service、pod 的变化，当得到这些变化信息后，Ingress controller 再结合 Ingress 的配置，更新反向代理负载均衡器，达到服务发现的作用.

在Kubernetes 目前 提供了以下几种方案：
NodePort
LoadBalancer
Ingress

使用ingress-nginx，先创建pod服务，默认yaml文件

wget  https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/mandatory.yaml

vim mandatory.yaml

apiVersion: v1
kind: Namespace
metadata:
  name: ingress-nginx

---

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: default-http-backend
  labels:
    app.kubernetes.io/name: default-http-backend
    app.kubernetes.io/part-of: ingress-nginx
  namespace: ingress-nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: default-http-backend
      app.kubernetes.io/part-of: ingress-nginx
  template:
    metadata:
      labels:
        app.kubernetes.io/name: default-http-backend
        app.kubernetes.io/part-of: ingress-nginx
    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: k8s.gcr.io/defaultbackend-amd64:1.5
          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.kubernetes.io/name: default-http-backend
    app.kubernetes.io/part-of: ingress-nginx
spec:
  ports:
    - port: 80
      targetPort: 8080
  selector:
    app.kubernetes.io/name: default-http-backend
    app.kubernetes.io/part-of: ingress-nginx

---

kind: ConfigMap
apiVersion: v1
metadata:
  name: nginx-configuration
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---

kind: ConfigMap
apiVersion: v1
metadata:
  name: tcp-services
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---

kind: ConfigMap
apiVersion: v1
metadata:
  name: udp-services
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---

apiVersion: v1
kind: ServiceAccount
metadata:
  name: nginx-ingress-serviceaccount
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
  name: nginx-ingress-clusterrole
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
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
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: 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

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: RoleBinding
metadata:
  name: nginx-ingress-role-nisa-binding
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: 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
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: nginx-ingress-clusterrole
subjects:
  - kind: ServiceAccount
    name: nginx-ingress-serviceaccount
    namespace: ingress-nginx

---

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx-ingress-controller
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: ingress-nginx
      app.kubernetes.io/part-of: ingress-nginx
  template:
    metadata:
      labels:
        app.kubernetes.io/name: ingress-nginx
        app.kubernetes.io/part-of: ingress-nginx
      annotations:
        prometheus.io/port: "10254"
        prometheus.io/scrape: "true"
    spec:
      serviceAccountName: nginx-ingress-serviceaccount
      hostNetwork: true
      nodeSelector: 
        app: ingress
      containers:
        - name: nginx-ingress-controller
          image: quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.20.0
          args:
            - /nginx-ingress-controller
            - --default-backend-service=$(POD_NAMESPACE)/default-http-backend
            - --configmap=$(POD_NAMESPACE)/nginx-configuration
            - --tcp-services-configmap=$(POD_NAMESPACE)/tcp-services
            - --udp-services-configmap=$(POD_NAMESPACE)/udp-services
            - --publish-service=$(POD_NAMESPACE)/ingress-nginx
            - --annotations-prefix=nginx.ingress.kubernetes.io
          securityContext:
            capabilities:
              drop:
                - ALL
              add:
                - NET_BIND_SERVICE
            # www-data -> 33
            runAsUser: 33
          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
---

将ingress固定漂移到node02节点上

[root@master ingress-nginx]# kubectl get no
NAME      STATUS    ROLES     AGE       VERSION
master    Ready     master    9d        v1.10.0
node02    Ready     <none>    8d        v1.10.0

给node02节点打上lable标签,设置hostNetwork: true提高网络访问效率

kubectl label node node02 app=ingress

yaml文件配置好，lable标签也打好开始创建ingress

kubectl apply -f mandatory.yaml 

查看pod状态

[root@master ingress-nginx]# kubectl get pod -n ingress-nginx
NAME                                        READY     STATUS    RESTARTS   AGE
default-http-backend-66c4fbf5b4-vkrzq       1/1       Running   4          21h
nginx-ingress-controller-658cd45944-tqgvm   1/1       Running   1          21h

# default
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：

创建i一个ingress-demo测试一下,首先创建tomcat

---
# deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-demo
spec:
  selector:
    matchLabels:
      app: tomcat-demo
  replicas: 1
  template:
    metadata:
      labels:
        app: tomcat-demo
    spec:
      containers:
      - name: tomcat-demo
        image: registry.cn-hangzhou.aliyuncs.com/liuyi01/tomcat:8.0.51-alpine
        ports:
        - containerPort: 8080

---
# service
apiVersion: v1
kind: Service
metadata:
  name: tomcat-demo 
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 8080
  selector:
    app: tomcat-demo

---
#ingress
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: tomcat-demo
spec:
  rules:
  - host: ingress1.com 
    http:
      paths:
      - path: /
        backend:
          serviceName: tomcat-demo
          servicePort: 8080

在创建一个nginx服务测试

# deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-demo
spec:
  selector:
    matchLabels:
      app: tomcat-demo
  replicas: 1
  template:
    metadata:
      labels:
        app: tomcat-demo
    spec:
      containers:
      - name: tomcat-demo
        image: registry.cn-hangzhou.aliyuncs.com/liuyi01/tomcat:8.0.51-alpine
        ports:
        - containerPort: 8080

---
# service
apiVersion: v1
kind: Service
metadata:
  name: tomcat-demo 
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 8080
  selector:
    app: tomcat-demo

---
#ingress
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: tomcat-demo
spec:
  rules:
  - host: ingress2.com 
    http:
      paths:
      - path: /
        backend:
          serviceName: tomcat-demo
          servicePort: 8080

创建nginx和tomcat pod服务

[root@master nginx-ingress]# kubectl apply -f .
# 查看pod情况，服务都起来了
[root@master nginx-ingress]# kubectl get pod 
NAME                              READY     STATUS    RESTARTS   AGE
load-generator-7bbbb4fdd4-l5vmz   1/1       Running   9          8d
myapp-deploy-6b9c9f847c-d6fsp     1/1       Running   0          2h
mynginx-85f8f5d89c-mhhzc          1/1       Running   0          2h
nginx-demo-6c5d64fd5f-xnscz       1/1       Running   0          1h
testservice-796fbc64bb-bczbs      1/1       Running   8          7d
tomcat-demo-686b48d96c-zxfpt      1/1       Running   0          2h

配置域名解析，当前测试环境我们使用hosts文件进行解析

192.168.14.32  ingress1.com
192.168.14.32  ingress2.com

接下来通过不同域名去访问，得到不同服务