云计算
为了对外发布pod内的应用，k8s支持两种负载均衡机制
1、一种是service，用于实现四层TCP负载均衡
service主要实现集群内部通信，以及基于四层的内外通信（如端口）
2、另一种是ingress，用户实现七层HTTP负载均衡
ingress主要实现基于七层的内外通信（如URL）
ingress仅仅是一组路由规则的集合，它需要借助ingress控制器才能发挥作用
ingress控制器不受controller-manager管理，它作为一个附件直接运行在k8s集群上
ingress控制器本身也是以pod形式运行，它与被代理的pod运行在同一个网络
和service不同的是，要使用ingress，必须先创建ingress-controller这个pod和基于该pod的svc
对于小规模的应用我们使用 NodePort 或许能够满足我们的需求，但是当你的应用越来越多的时候，你就会发现对于 NodePort 的管理就非常麻烦了，这个时候使用 ingress 就非常方便了，可以避免管理大量的 Port。
igress类型
1、单service资源型
2、基于URL路径进行转发
3、基于虚拟主机进行转发
4、TLS类型
ingress控制器可以由如下反向代理程序实现：
1、haproxy
2、nginx
3、envoy
4、traefik
5、Vulcand
创建基于treafik的ingress
1、创建rbac认证
apiVersion: v1
kind: ServiceAccount
metadata:
name: traefik-ingress-controller
namespace: kube-system
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: traefik-ingress-controller
rules:
- apiGroups:
-
resources:
- services
- endpoints
- secrets
verbs:
- get
- list
- watch
- apiGroups:
- extensions
resources:
- ingresses
verbs:
- get
- list
- watch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: traefik-ingress-controller
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: traefik-ingress-controller
subjects:
- kind: ServiceAccount
name: traefik-ingress-controller
namespace: kube-system$ kubectl create -f rbac.yaml
serviceaccount "traefik-ingress-controller" created
clusterrole.rbac.authorization.k8s.io "traefik-ingress-controller" created
clusterrolebinding.rbac.authorization.k8s.io "traefik-ingress-controller" created
2、创建基于treafik的ingress控制器pod及svc
将该控制器pod部署在master上
$ docker pull traefik
$ vim traefik.yaml
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
name: traefik-ingress-controller
namespace: kube-system
labels:
k8s-app: traefik-ingress-lb
spec:
replicas: 1
selector:
matchLabels:
k8s-app: traefik-ingress-lb
template:
metadata:
labels:
k8s-app: traefik-ingress-lb
name: traefik-ingress-lb
spec:
serviceAccountName: traefik-ingress-controller
terminationGracePeriodSeconds: 60
tolerations:
- operator: Exists #允许污点
nodeSelector:
kubernetes.io/hostname: master #部署在master上
containers:
- image: traefik
name: traefik-ingress-lb
ports:
- name: http
containerPort: 80
hostPort: 80 #外网访问时不用使用nodePort端口，直接使用域名即可
- name: admin
containerPort: 8080
args:
- --api
- --kubernetes
- --logLevel=INFO
---
kind: Service
apiVersion: v1
metadata:
name: traefik-ingress-service
namespace: kube-system
spec:
selector:
k8s-app: traefik-ingress-lb
ports:
- protocol: TCP
port: 80
name: web
- protocol: TCP
port: 8080
name: admin
type: NodePort因为traefik容器中有两个端口，80和8080（管理端口），所以其对应的服务中也需要两个端口80和8080.
$ kubectl apply -f traefik.yaml
deployment.extensions "traefik-ingress-controller" created
service "traefik-ingress-service" created
$ kubectl get svc -n kube-system
traefik-ingress-service NodePort 10.100.222.78
通过svc访问traefik的管理界面
http://192.168.1.243:31572/
3、为上述ingress控制器及其svc本身（8080）创建ingress实例
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: traefik-web-ui
namespace: kube-system
annotations:
kubernetes.io/ingress.class: traefik
spec:
rules:
- host: traefik.example.com
http:
paths:
- backend:
serviceName: traefik-ingress-service
servicePort: 8080模拟dns解析
$ vim /etc/hosts
192.168.1.243 traefik.example.com
因为pod中有hostPort: 80 ，所以能够以ingress的方式直接使用域名访问traefik的管理界面
https://traefik.example.com
如果你有多个master的话，可以在每个master上部署一个 ingress-controller 服务，然后在master前面挂一个负载均衡器，比如 nginx，将所有的master均作为这个负载均衡器的后端，这样就可以实现 ingress-controller 的高可用和负载均衡了。
4、定义后端普通应用pod及其svc
svc的type为ClusterIP
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
name: svc1
spec:
replicas: 1
template:
metadata:
labels:
app: svc1
spec:
containers:
- name: svc1
image: cnych/example-web-service
env:
- name: APP_SVC
value: svc1
ports:
- containerPort: 8080
protocol: TCP
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
name: svc2
spec:
replicas: 1
template:
metadata:
labels:
app: svc2
spec:
containers:
- name: svc2
image: cnych/example-web-service
env:
- name: APP_SVC
value: svc2
ports:
- containerPort: 8080
protocol: TCP
---
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
name: svc3
spec:
replicas: 1
template:
metadata:
labels:
app: svc3
spec:
containers:
- name: svc3
image: cnych/example-web-service
env:
- name: APP_SVC
value: svc3
ports:
- containerPort: 8080
protocol: TCP
---
kind: Service
apiVersion: v1
metadata:
labels:
app: svc1
name: svc1
spec:
type: ClusterIP
ports:
- port: 8080
name: http
selector:
app: svc1
---
kind: Service
apiVersion: v1
metadata:
labels:
app: svc2
name: svc2
spec:
type: ClusterIP
ports:
- port: 8080
name: http
selector:
app: svc2
---
kind: Service
apiVersion: v1
metadata:
labels:
app: svc3
name: svc3
spec:
type: ClusterIP
ports:
- port: 8080
name: http
selector:
app: svc3$ kubectl create -f backend.yaml
deployment.extensions "svc1" created
deployment.extensions "svc2" created
deployment.extensions "svc3" created
service "svc1" created
service "svc2" created
service "svc3" created
5、为上述普通应用pod及其svc定义ingress策略
ingress策略的后端是应用pod的svc
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: example-web-app
annotations:
kubernetes.io/ingress.class: traefik
spec:
rules:
- host: www.example.com
http:
paths:
- path: /s1
backend:
serviceName: svc1
servicePort: 8080
- path: /s2
backend:
serviceName: svc2
servicePort: 8080
- path: /
backend:
serviceName: svc3
servicePort: 8080$ kubectl create -f example-ingress.yaml
ingress.extensions "example-web-app" created
$ kubectl get ingress
$ kubectl describe ingress example-web-app
模拟dns
$ vim /etc/hosts
192.168.1.243 www.example.com
http://www.example.com ---访问svc3
http://www.example.com/s1 ---访问svc1
http://www.example.com/s2 ---访问svc2
6、使traefik ingress支持TLS
要使其支持tls需要三个方面的支持
一、生成ca证书
$ mkdir /ssl
$ cd /ssl
$ openssl req -newkey rsa:2048 -nodes -keyout tls.key -x509 -days 365 -out tls.crt
$ ls
tls.crt tls.key
然后创建secret用于存储证书
$ kubectl create secret generic traefik-cert --from-file=tls.crt --from-file=tls.key -n kube-system
$ kubectl get secret -n kube-system |grep traefik
二、增加默认配置文件traefik.toml
该文件和traefik pod文件在同一个目录
$ vim traefik.toml
defaultEntryPoints = [http, https]
[entryPoints]
[entryPoints.http]
address = :80
[entryPoints.http.redirect]
entryPoint = https
[entryPoints.https]
address = :443
[entryPoints.https.tls]
[[entryPoints.https.tls.certificates]]
CertFile = /ssl/tls.crt
KeyFile = /ssl/tls.key创建configmap用于存储该配置文件
$ kubectl create configmap traefik-conf --from-file=traefik.toml -n kube-system
$ kubectl get configmap -n kube-system |grep traefik
三、修改第2步中的 traefik pod 的 yaml文件
$ vim traefik.yaml
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
name: traefik-ingress-controller
namespace: kube-system
labels:
k8s-app: traefik-ingress-lb
spec:
replicas: 1
selector:
matchLabels:
k8s-app: traefik-ingress-lb
template:
metadata:
labels:
k8s-app: traefik-ingress-lb
name: traefik-ingress-lb
spec:
serviceAccountName: traefik-ingress-controller
terminationGracePeriodSeconds: 60
volumes:
- name: ssl
secret:
secretName: traefik-cert
- name: config
configMap:
name: traefik-conf
tolerations:
- operator: Exists
nodeSelector:
kubernetes.io/hostname: master
containers:
- image: traefik
name: traefik-ingress-lb
volumeMounts:
- mountPath: /ssl
name: ssl
- mountPath: /config
name: config
ports:
- name: http
containerPort: 80
hostPort: 80
- name: https
containerPort: 443
hostPort: 443
- name: admin
containerPort: 8080
args:
- --configfile=/config/traefik.toml
- --api
- --kubernetes
- --logLevel=INFO$ kubectl apply -f traefik.yaml
$ kubectl logs -f traefik-ingress-controller-7dcfd9c6df-v58k7 -n kube-system
time="2018-08-26T11:26:44Z" level=info msg="Server configuration reloaded on :80"
time="2018-08-26T11:26:44Z" level=info msg="Server configuration reloaded on :443"
time="2018-08-26T11:26:44Z" level=info msg="Server configuration reloaded on :8080"