k8s中负载均衡器【ingress-nginx】部署

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

本节主要就ingress和ingress控制器ingress-nginx-controller的部署作简单介绍和记录。

以下系统组件版本：

云服务器：centos版本7.6.1810、k8s版本1.15.0、docker版本18.06.1-ce、ingress-nginx-controller版本0.25.0

ingress

ingress 组成？

• 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

• 将新加入的ingress转化成nginx的配置文件并使之生效

• ingress controller

• ingress服务

ingress 工作原理?

• ingress controller通过和kubernetes api交互，动态的去感知集群中ingress规则变化，
• 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，
• 再写到nginx-ingress-controller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，
• 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？

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.

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

ingress当前的实现方式？

ingress-nginx-controller

目前最新版本的ingress-nginx-controller，用lua实现了当upstream变化时不用reload，大大减少了生产环境中由于服务的重启、升级引起的ip变化导致的nginx reload。

以下就ingress-nginx-controller的部署做简单记录：

yaml如下：

kubectl apply -f {如下文件}

apiversion: v1
kind: namespace
metadata:
  name: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    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:
      - ""
    resources:
      - events
    verbs:
      - create
      - patch
  - apigroups:
      - "extensions"
      - "networking.k8s.io"
    resources:
      - ingresses
    verbs:
      - get
      - list
      - watch
  - apigroups:
      - "extensions"
      - "networking.k8s.io"
    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:0.25.0
          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:
            allowprivilegeescalation: true
            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: 10
          readinessprobe:
            failurethreshold: 3
            httpget:
              path: /healthz
              port: 10254
              scheme: http
            periodseconds: 10
            successthreshold: 1
            timeoutseconds: 10

---

在墙内会拉取不到以下镜像：

quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.25.0

可以使用国内阿里云镜像：

docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/nginx-ingress-controller:0.25.0

安装后，在ingress-nginx命名空间下可以看到pod一直pending，describe pod报如下警告：

查看master节点默认加了污点，一般不允许pod调度到master节点：

如果k8s集群只有一个节点，可以在pod的spec下设置容忍该污点：

即：

   spec:      
      tolerations:
      - effect: noschedule
        key: node-role.kubernetes.io/master

可以看到ingress-nginx pod被调度到master节点，且变为running

看日志报以下警告：

w0714 13:31:04.883127       6 queue.go:130] requeuing &objectmeta{name:sync status,generatename:,namespace:,selflink:,uid:,resourceversion:,generation:0,creationtimestamp:0001-01-01 00:00:00 +0000 utc,deletiontimestamp:<nil>,deletiongraceperiodseconds:nil,labels:map[string]string{},annotations:map[string]string{},ownerreferences:[],finalizers:[],clustername:,initializers:nil,managedfields:[],}, err services "ingress-nginx" not found

需要创一个名为ingress-nginx的service：

kubectl apply -f {如下文件}
kind: service
apiversion: v1
metadata:
  name: ingress-nginx
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  externaltrafficpolicy: local
  type: loadbalancer
  selector:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
  ports:
    - name: http
      port: 80
      targetport: http
    - name: https
      port: 443
      targetport: https

参考：

ingress deploy

taint和toleration（污点和容忍）

k8s 1.12部署ingress-nginx

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