Kubernetes Service定义了这样一种抽象:一个Pod的逻辑分组,一种可以访问它们的策略-通常称为微服务。这一组Pod能够被Service访问到,通常是通过Label selector
Service能够提供负载均衡的能力,但是在使用上有以下限制:
Service在K8s中有以下四种类型
在Kubernetes集群中,每个Node运行一个kube-proxy进程。kube-proxy负责为Service实现了一种 VIP (虚拟IP)的形式,而不是ExternalName的形式。在Kubernetes v1.0版本,代理完全在userspace.在 Kubernetes v1.1版本,新增了iptables代理,但并不是默认的运行模式。从Kubernetes v1.2起,默认就是 iptables代理。在Kubernetes v1.8.0-beta.0中,添加了ipvs代理 在Kubernetes 1.14版本开始默认使用ipvs代理
在Kubernetes v1.0版本, Service是"4层" (TCP/UDP over IP)概念。在Kubernetes v1.1版本,新增了 Ingress API (beta版) ,用来表示"7层" (HTTP)服务
!为何不使用round-robin DNS? 会缓存ip等信息
这种模式, kube-proxy会监视Kubernetes Service对象和Endpoints ,调用netlink接口以相应地创建 ipvs规则并定期与Kubernetes Service对象和Endpoints对象同步ipvs规则,以确保ipvs状态与期望致。访问服务时,流量将被重定向到其中一个后端Pod
与iptables类似, ipvs于netfilter的hook功能,但使用哈希表作为底层数据结构并在内核空间中工作。这意味着ipvs可以更快地重定向流量,并且在同步代理规则时具有更好的性能。此外, ipvs为负载均衡算法提供了更多选项,例如:
clusterlP主要在每个node节点使用iptables,将发向clusterlP对应端口的数据,转发到kube-proxy中。然后kube-proxy自己内部实现有负载均衡的方法,并可以查询到这个service下对应pod的地址和端口,进而把数据转发给对应的pod的地址和端口
为了实现图上的功能,主要需要以下几个组件的协同工作:
创建myapp-deploy.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: myapp-deploy
namespace: default
spec:
replicas: 3
selector:
matchLabels:
app: myapp
release: stabel
template:
metadata:
labels:
app: myapp
release: stabel
env: test
spec:
containers:
- name: myapp
image: wangyanglinux/myapp:v2
imagePullPolicy: IfNotPresent
ports:
- name: http
containerPort: 80
创建service信息--vim myapp-service.yaml
apiVersion: v1
kind: Service
metadata:
name: myapp
namespace: default
spec:
type: ClusterIP
selector:
app: myapp
release: stabel
ports:
- name: http
port: 80
targetPort: 80
有时不需要或不想要负载均衡,以及单独的Service IP,遇到这种情况,可以通过指定Cluster IP(spec.clusterlP)的值为"None"来创建Headless Service,这类Service并不会分配Cluster IP, kube proxy不会处理它们,而且平台也不会为它们进行负载均衡和路由
apiVersion: v1
kind: Service
metadata:
name: myapp-headless
namespace: default
spec:
selector:
app:myapp
clusterIP: "None"
ports:
- port: 80
targetPort: 80
nodePort的原理在于在node上开了一个端口,将向该端口的流量导入到kube-proxy,然后由kube-proxy进一步到给对应的pod
apiVersion: v1
kind: Service
metadata:
name: myapp
namespace: default
spec:
type: NodePort
selector:
app: myapp
release: stabel
ports:
- name: http
port: 80
targetPort: 80
ipvsadm -Ln ip地址
yum -y install bind-utils 安装dig命令
dig -t A myapp-headless.default.svc.cluster.local. @10.96.0.10
netstat -anpt | grep :20715
查询流程
iptables -t nat -nvL
KUBE-NODEPORTS
loadBalancer和nodePort其实是同一种方式。区别在于loadBalancer比nodePort多了一步,就是可以调用 cloud provider去创建LB来向节点导流
这种类型的Service通过返回CNAME和它的值,可以将服务映射到externalName字段的内容(例如: hub.atguigu.com ), ExternalName Service是Service的特例,它没有selector,也没有定义任何的端口和 Endpoint,相反的,对于运行在集群外部的服务,它通过返回该外部服务的别名这种方式来提供服务
kind: Service
apiVersion: v1
metadata:
name: my-service-1
namespace: default
spec:
type: ExternalName
externalName: hub.atguigu.com
当查询主机my-service.defalut.svc.cluster.local ( SVC NAME.NAMESPACE.svc.cluster.local )时,集群的 DNS服务将返回一个值my.database.example.com的CNAME记录。访问这个服务的工作方式和其他的相司,唯一不同的是重定向发生在DNS层,而且不会进行代理或转发
Ingress-Nginx github地址: https://github.com/kubernetes/ingress-nginxI
ngress-Nginx官方网站: https://kubernetes.github.io/ingress-nginx/
kubect1 apply -f mandatory.yam1
kubectl apply -f service-nodeport.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/mandatory.yaml
wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/mandatory.yaml
wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/mandatory.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/mandatory.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/provider/baremetal/service-nodeport.yaml
wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/provider/baremetal/service-nodeport.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/provider/baremetal/service-nodeport.yaml
docker save -o ingress.contr.tar quay. io/kubernet es-ingress-controller/nginx-ingress-controller:0.25.0 将镜像封装
tar -zcvf ingress.contr.tar.gz ingress.contr.tar 压缩
sz ingress.contr.tar.gz 导出
rz 导入
tar -zxvf ingree.contro.tar.gz 解压
docker load -i ingree.contro.tar docker将压缩镜像导入
deployment, Service, Ingress Yaml文件
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: nginx-dm
spec:
replicas: 2
template:
metadata:
labels:
name: nginx
spec:
containers:
- name: nginx
image: wangyanglinux/myapp:v1
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
name: nginx-svc
spec:
ports:
- port: 80
targetPort: 80
protocol: TCP
selector:
name: nginx
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: nginx-test
spec:
rules:
- host: www1.atguigu.com
http:
paths:
- path: /
backend:
serviceName: nginx-svc
servicePort: 80
访问创建证书,以及cert存储方式
openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:2048 -keyout tls.key -out tls.crt -subj "/CN=nginxsvc/0=nginxsvc"
kubectl create secret tls tls-secret --key tls.key --cert tls.crt
deployment, Service, Ingress Yaml文件
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: nginx-test
spec:
tls:
- hosts:
- www3.atguigu.com
secretName: tls-secret
rules:
- host: www3.atguigu.com
http:
paths:
- path: /
backend:
serviceName: nginx-svc
servicePort: 80
yum -y install httpd
htpasswd -c auth foo
kubectl create secret generic basic-auth --from-file=auth
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: ingress-with-auth
annotations:
nginx.ingress.kubernetes.io/auth-type: basic
nginx.ingress.kubernetes.io/auth-secret: basic-auth
nginx.ingress.kubernetes.io/auth-realm: 'Authentication Required - foo'
spec:
rules:
- host: foo2.bar.com
http:
paths:
- path: /
backend:
serviceName: nginx-svc
serviceport: 80
kubectl get ingress
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: nginx-test
annotations:
nginx.ingress.kubernetes.io/rewrite-target: http://foo.bar.com:31795/hostname.html
spec:
rules:
- host: foo10.bar.com
http:
paths:
- path: /
backend:
serviceName: nginx-svc
servicePort: 80