kubernetes部署Ingress访问代理与负载均衡器-阿里云开发者社区

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kubernetes部署Ingress访问代理与负载均衡器

简介: Kubernetes中的pod都有独立的内部IP(外部不可访问),通过Service可以对多个pod进行负载均衡和故障转移,Service可以具有ClusterIP、NodeIP或LoadBanlancer模式。

Kubernetes中的pod都有独立的内部IP(外部不可访问),通过Service可以对多个pod进行负载均衡和故障转移,Service可以具有ClusterIP、NodeIP或LoadBanlancer模式。目前,ClusterIP只能内部访问,需通过kubectl proxy代理出来,NodeIP是跟Node绑定的、迁移性差,LoadBanlancer的每个服务都有独立的IP地址,管理、使用不便。有没有一个固定的独立IP、自动节点漂 移的解决方案呢?以前这样的功能基本上都用Nginx来实现,现在Kubernetes有一个做好了的服务,也是基于Nginx的,就是Ingress。

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如何访问K8S中的服务:

image.png

1、Ingress介绍

Kubernetes 暴露服务的方式目前只有三种:LoadBlancer Service、NodePort Service、Ingress;前两种估计都应该很熟悉,下面详细的了解下这个 Ingress

Ingress由两部分组成:Ingress Controller 和 Ingress 服务。

Ingress Contronler 通过与 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-control的 Pod 里,这个 Ingress Contronler 的pod里面运行着一个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 使用配置生效。以此来达到域名分配置及动态更新的问题。

看个简单的图方便理解:

image.png

ingress控制器有两种:nginx和haproxy 这里是以nginx为讲解。

2、部署一个Nginx Ingress

ingress的部署文件在github Ingress 仓库找到. 针对官方配置我们单独添加了 nodeselector 指定,绑定LB地址 以方便DNS 做解析。

主要用到的文件:

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$ ls

default-backend.yaml jenkins-ingress.yml nginx-ingress-controller-rbac.yml nginx-ingress-controller.yaml

- - -

default-backend.yaml:这是官方要求必须要给的默认后端,提供404页面的。它还提供了一个http检测功能,检测nginx-ingress-controll健康状态的,通过每隔一定时间访问nginx-ingress-controll的/healthz页面,如是没有响应就

返回404之类的错误码。

nginx-ingress-controller-rbac.yml:这ingress的RBAC授权文件

nginx-ingress-controller.yaml:这是控制器的部署文件。

jenkins-ingress.yml:这是Ingress服务文件,这个可以是任意web程序,里面配置域名与service的对应关系,Ingress称之为规则。

第一个是要部署RBAC文件:

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cat nginx-ingress-controller-rbac.yml

#apiVersion: v1

#kind: Namespace

#metadata: #这里是创建一个namespace,因为此namespace早有了就不用再创建了

# name: kube-system

---

apiVersion: v1

kind: ServiceAccount

metadata:

name: nginx-ingress-serviceaccount #创建一个serveerAcount

namespace: kube-system

---

apiVersion: rbac.authorization.k8s.io/v1beta1

kind: ClusterRole

metadata:

name: nginx-ingress-clusterrole #这个ServiceAcount所绑定的集群角色

rules:

- apiGroups:

- ""

resources: #此集群角色的权限,它能操作的API资源

- 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 #这是一个角色,而非集群角色

namespace: kube-system

rules: #角色的权限

- 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 #角色绑定

metadata:

name: nginx-ingress-role-nisa-binding

namespace: kube-system

roleRef:

apiGroup: rbac.authorization.k8s.io

kind: Role

name: nginx-ingress-role

subjects:

- kind: ServiceAccount

name: nginx-ingress-serviceaccount #绑定在这个用户

namespace: kube-system

---

apiVersion: rbac.authorization.k8s.io/v1beta1

kind: ClusterRoleBinding #集群绑定

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 #集群绑定到这个serviceacount

namespace: kube-system #集群角色是可以跨namespace,但是这里只指明给这个namespce来使用

创建:

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$ kubectl create -f nginx-ingress-controller-rbac.yml

serviceaccount "nginx-ingress-serviceaccount" created

clusterrole "nginx-ingress-clusterrole" created

role "nginx-ingress-role" created

rolebinding "nginx-ingress-role-nisa-binding" created

clusterrolebinding "nginx-ingress-clusterrole-nisa-binding" created

RBAC创建完后,就创建default backend服务:

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$ cat default-backend.yaml

apiVersion: extensions/v1beta1

kind: Deployment

metadata:

name: default-http-backend

labels:

k8s-app: default-http-backend

namespace: kube-system

spec:

replicas: 1

template:

metadata:

labels:

k8s-app: default-http-backend

spec:

terminationGracePeriodSeconds: 60

containers:

- name: default-http-backend

# Any image is permissable as long as:

# 1. It serves a 404 page at /

# 2. It serves 200 on a /healthz endpoint

image: gcr.io/google_containers/defaultbackend:1.0

livenessProbe:

httpGet:

path: /healthz #这个URI是 nginx-ingress-controller中nginx里配置好的localtion

port: 8080

scheme: HTTP

initialDelaySeconds: 30 #30s检测一次/healthz

timeoutSeconds: 5

ports:

- containerPort: 8080

resources:

limits:

cpu: 10m

memory: 20Mi

requests:

cpu: 10m

memory: 20Mi

nodeSelector: #指定调度到些Node, 以便后面DNS解析

kubernetes.io/hostname: 10.3.1.17

---

apiVersion: v1

kind: Service #为default backend 创建一个service

metadata:

name: default-http-backend

namespace: kube-system

labels:

k8s-app: default-http-backend

spec:

ports:

- port: 80

targetPort: 8080

selector:

k8s-app: default-http-backend

创建:

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$ kubectl create -f default-backend.yaml

deployment "default-http-backend" created

service "default-http-backend" created

创建之后查看:

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root@ubuntu15:/data/ingress# kubectl get rs,pod,svc -n kube-system

NAME DESIRED CURRENT READY AGE

rs/default-http-backend-857b544d94 1 1 1 1m

NAME READY STATUS RESTARTS AGE

po/default-http-backend-857b544d94-bwgjd 1/1 Running 0 1m

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE

svc/default-http-backend ClusterIP 10.254.208.144 <none> 80/TCP 1m

创建好default backend后就要创建nginx-ingress-controller了:

$ cat nginx-ingress-controller.yaml 

apiVersion: extensions/v1beta1 kind: Deployment metadata:

 name: nginx-ingress-controller

 labels:

 k8s-app: nginx-ingress-controller

 namespace: kube-system

spec:

 replicas: 1

 template:

 metadata:

 labels:

 k8s-app: nginx-ingress-controller

 spec:

 # hostNetwork makes it possible to use ipv6 and to preserve the source IP correctly regardless of docker configuration # however, it is not a hard dependency of the nginx-ingress-controller itself and it may cause issues if port 10254 already is taken on the host # that said, since hostPort is broken on CNI (https://github.com/kubernetes/kubernetes/issues/31307) we have to use hostNetwork where CNI is used # like with kubeadm # hostNetwork: true #注释表示不使用宿主机的80口,

 terminationGracePeriodSeconds: 60

 hostNetwork: true #表示容器使用和宿主机一样的网络

 serviceAccountName: nginx-ingress-serviceaccount #引用前面创建的serviceacount

 containers: 

 - image: gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.1 #容器使用的镜像

 name: nginx-ingress-controller #容器名

 readinessProbe: #启动这个服务时要验证/healthz 端口10254会在运行的node上监听。 

 httpGet:

 path: /healthz

 port: 10254

 scheme: HTTP

 livenessProbe:

 httpGet:

 path: /healthz

 port: 10254

 scheme: HTTP

 initialDelaySeconds: 10 #每隔10做健康检查 

 timeoutSeconds: 1

 ports:

 - containerPort: 80 

 hostPort: 80 #80映射到80

 - containerPort: 443

 hostPort: 443

 env:

 - name: POD_NAME

 valueFrom:

 fieldRef:

 fieldPath: metadata.name

 - name: POD_NAMESPACE

 valueFrom:

 fieldRef:

 fieldPath: metadata.namespace

 args:

 - /nginx-ingress-controller

 - --default-backend-service=$(POD_NAMESPACE)/default-http-backend

# - --default-ssl-certificate=$(POD_NAMESPACE)/ingress-secret #这是启用Https时用的

 nodeSelector: #指明运行在哪,此IP要和default backend是同一个IP

 kubernetes.io/hostname: 10.3.1.17 #上面映射到了hostport80,确保此IP80,443没有占用.

这个控制器就是一个deployment ,里面运行一个容器gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.1 ,有点像nginx容器,现在创建:

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$ kubectl create -f nginx-ingress-controller.yaml

deployment "nginx-ingress-controller" created

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root@ubuntu15:/data/ingress# kubectl get rs,pod,svc -n kube-system

NAME DESIRED CURRENT READY AGE

rs/default-http-backend-857b544d94 1 1 1 12m

rs/nginx-ingress-controller-8576d4545d 1 1 0 27s

NAME READY STATUS RESTARTS AGE

po/default-http-backend-857b544d94-bwgjd 1/1 Running 0 12m

po/nginx-ingress-controller-8576d4545d-9tjnv 0/1 ContainerCreating 0 27s

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE

svc/default-http-backend ClusterIP 10.254.208.144 <none> 80/TCP 12m

现在ingress controller 控制器已部署好了,那么如何使用了,那就要写一个ingress规则了,此处就以已存在的jenkins服务为例,配置如何使用域名访问这个service:

$ kubectl get svc,ep

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE

svc/jenkinsservice NodePort 10.254.70.47 <none> 8080:30002/TCP 3h

NAME ENDPOINTS AGE

ep/jenkinsservice 172.30.10.15:8080,172.30.11.7:8080 3h

现在写个jenkins service的Ingress 规则:

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$ cat jenkins-ingress.yml

apiVersion: extensions/v1beta1

kind: Ingress

metadata:

name: jenkins-ingress

namespace: default #服务在哪个空间内就写哪个空间

annotations:

kubernetes.io/ingress.class: "nginx"

spec:

rules:

- host: ingress.jenkins.com #此service的访问域名

http:

paths:

- backend:

serviceName: jenkinsservice

servicePort: 8080

创建它:

$ kubectl create -f jenkins-ingress.yml 
ingress "jenkins-ingress" created

$ kubectl get ingress 
NAME HOSTS ADDRESS PORTS AGE
jenkins-ingress ingress.jenkins.com 80 10s

到这里就已经部署完成了,配置好域名后,就可以用此域名来访问了:

image.png

部署完成了,现在看下nginx-ingress-controller 里nginx配置文件发生了哪些变化:

upstream default-jenkinsservice-8080 {
 least_conn;
 server 172.30.10.15:8080 max_fails=0 fail_timeout=0;
 server 172.30.11.7:8080 max_fails=0 fail_timeout=0;
 }

upstream upstream-default-backend {
 least_conn;
 server 172.30.11.6:8080 max_fails=0 fail_timeout=0;
 }

server {
 server_name ingress.jenkins.com;
 listen [::]:80;
 location / {
 ...
 proxy_pass http://default-jenkinsservice-8080;
 ...
 }
 }

这些配置都是ingress-controller 自已写入的,动态更新就是它能通过K8S API感知到service的endpoint 发生了变化,然后修改nginx配置并执行reload.

至此,部署完成。

Ingress还有很多部署方式,比如配置https访问的, 以后再写。

本文转自开源中国-kubernetes部署Ingress访问代理与负载均衡器

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