Ingress初体验

前言

service暴露的三种方式ClusterIP、NodePort与LoadBalance，这三种都是在service的维度提供的。
service的作用体现在2个方面:
1. 对集群内部，它不断跟踪pod的变化更新endpoint中对应pod的对象，提供了ip不断变化的pod的服务发现机制。
2. 对集群外部，它类似负载均衡器，可以在集群内外部对pod进行访问。

但单独用service暴露服务的方式在实际生产环境中不太适用：
1. ClusterIP的方式只能在集群内部访问
2. NodePort方式在测试环境使用还行，但是有成百上千服务在集群中运行时，NodePort的端口管理很是麻烦。
3. LoadBalance方式受限于云平台，而且需要额外费用。最大缺点是每个service用一个LB既浪费又麻烦。

ingress

ingress则只需要一个NodePort或者一个LB就可满足所有service对外服务的需求。
ingress相当于一个7层负载均衡器，是k8s对反向代理的一个抽象。
Ingress Contronler 通过与 Kubernetes API 交互，能够动态的获取cluster中Ingress rules的变化，生成一段 Nginx 配置，再写到 Nginx-ingress-control的 Pod 里，reload pod 使规则生效。
从而实现注册的service及其对应域名/IP/Port的动态添加和解析。

mark

ingress组成

1	包括：ingress controller和ingress resources

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ingress controller：核心是一个deployment，实现方式有很多，比如nginx、contour、haproxy、Istio，需要编写的yaml有deploy、service、serviceaccount。其中service类型可以是NodePort或者LoadBalancer.
ingress-controller的形式都是一个pod，里面跑着daemon程序和反向代理程序。daemon负责不断监控集群的编号，根据ingress对象生成配置并应用新配置到反向代理，比如nginx-ingress就是动态生成nginx配置，动态更新upstream，并在需要的时候reload程序应用新配置。

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ingress
ingress resources: 就是一个类型为ingress的k8s api对象，通过yaml文件来配置。ingress通过http或https暴露集群内部service，给service提供外部URL、负载均衡、SSL/TLS能力以及基于host的方式代理。ingress要依靠ingress-controller来具体实现以上功能。

部署ingress-controller

# yaml部署，mandatory.yaml
apiVersion: v1
kind: Namespace
metadata:
  name: 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

---
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: apps/v1
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
      containers:
        - name: nginx-ingress-controller
          image: quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.21.0
          args:
            - /nginx-ingress-controller
            - --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

# service-ingress.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: 80
    - name: https
      port: 443
      targetPort: 443
      protocol: TCP
  selector:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

配置ingress

# 方式一
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-1
  namespace: default
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  # 配置七层域名
  - host: liyk.key1024.cn
    http:
      paths:
      # 配置Context Path
      - path: /nginx1
        backend:
          serviceName: myapp-svc
          servicePort: 80
      - path: /nginx2
        backend:
          serviceName: nginx
          servicePort: 80

# 说明
接着在hosts文件中添加一条解析规则：${ingress_IP} foo.bar.com，这时通过在浏览器中访问：foo.bar.com/coffee或者foo.bar.com/tea即可访问对应的后端service了

使用curl时的操作：curl -H "Host: foo.bar.com" http://${ingress_IP}/coffee

# 方式二
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: cafe-ingress
spec:
  rules:
  # 配置七层域名
  - host: tea.foo.bar.com
    http:
      paths:
      - backend:
          serviceName: tea-svc
          servicePort: 80
  - host: coffee.foo.bar.com
    http:
      paths:   
      - backend:
          serviceName: coffee-svc
          servicePort: 80

HTTPS TLS类型

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# 生成证书
openssl genrsa -out tls.key 2048
openssl req -new -x509-key tls.key -out tls.crt -subj /C=CN/ST/Beijing/L=Beijing/O=DevOps/CN=tomcat.key1024.cn -days 3650

1 2	# 创建secret kubectl create secret tls tomcat-ingress-secret --cert=tls.crt --key=tls.key

# tomcat-ingress-tls.yaml
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: tomcat-ingress-tls
  annotations:
    kubernetes.io/ingress.class: "nginx"
spec:
  tls:
  - hosts:
    - tomcat.key1024.cn
    secretName: tomcat-ingress-secret
  rules:
  - host: tomcat.key1024.cn
    http:
      paths:
      - path: /
        backend:
          serviceName: tomcat-svc
          servicePort: 80