Service概念
K8S的service定义了一种抽象: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,但是在使用上有限制:
只提供4层负载均衡能力,而没有7层功能,但有时我们需要更多的匹配规则来转发请求,这点上4层负载均衡是不支持的
service的类型
- ClusterIP:默认类型,自动分配一个仅Cluster内部可以访问的虚拟IP
- NodePort:在ClusterIP基础上为Service在每台机器上绑定一个端口,这样就可以通过<NodeIP>:NodePort来访问该
服务
- LoadBalancer:在NodePort的基础上,借助cloud provider创建一个外部负载均衡器,并将请求转发到<NodeIP>:NodePort
- ExternalName:把集群外部的服务引入到集群内部来,在集群内部直接使用。没有任何类型代理被创建

代理模式分类
1、userspace代理模式

2、iptables代理模式

3、ipvs代理模式
这种模式,kube-proxy会监视K8S的Service对象和Endpoints,调用netlink接口以相应地创建IPVS规则并定期与K8S
service对象同步IPVS规则,以确保ipvs状态与期望一致。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:
- Rr:轮询
- Lc:最小连接数
- Dh:目标哈希
- Sh:源哈希
- Sed:最短期望延迟
- nq:不排队调度

实验:
[root@k8s-master01 service]# cat server.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: myapp-deploy
spec:
replicas: 3
selector:
matchLabels:
app: myapp
release: stable
template:
metadata:
labels:
app: myapp
release: stable
env: test
spec:
containers:
- name: myapp
image: wangyanglinux/myapp:v1
imagePullPolicy: IfNotPresent
[root@k8s-master01 service]# cat service.yaml
---
apiVersion: v1
kind: Service
metadata:
name: myapp
spec:
ports:
- port: 80
name: http
targetPort: 80
selector:
app: myapp
release: stable
type: ClusterIP
Headless Service:
有时不需要或不想要负载均衡,以及单独的ClusterIP,可以通过指定ClusterIP(spec.clusterip)的值为"None"来创建Headless Service。
这类Service并不会分配Cluster IP,Kube-proxy不会处理他们,而且平台也不会它们进行负载均衡和路由
[root@k8s-master01 service]# cat headless-svc.yaml
---
apiVersion: v1
kind: Service
metadata:
name: myapp-headless
spec:
selector:
app: myapp
clusterIP: "None"
ports:
- port: 80
targetPort: 80
kubectl get pod -n kube-system -o wide

dig -t A myapp-headless.default.svc.cluster.local. @10.244.0.9
解析出来分配的IP依然是Pod的
kubectl get pod -o wide
NodePort
在node上开一个端口,将向该端口的流量导入到kube-proxy,然后有kube-proxy进一步到给对应的pod
[root@k8s-master01 service]# cat nodeport-svc.yaml
---
apiVersion: v1
kind: Service
metadata:
name: myapp
spec:
type: NodePort
selector:
app: myapp
release: stable
ports:
- name: http
port: 80
targetPort: 80
LoadBalancer
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。

ExternalName
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:test.k8s.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
---
apiVersion: v1
kind: Service
metadata:
name: my-service-1
spec:
type: ExternalName
externalName: k8s.test.com
当查询主机my-service.default.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同,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相关


ingress-controller的安装
国内安装ingress-controller拉去不了镜像
方法1:有国外服务器,在国外服务器上下载,下载好后将镜像导出来,打入node节点里面
方法2:在dockerhub上搜索看看是否有别人同步的镜像,在服务器上pull下来后重新打tag
$docker pull liangjw/kube-webhook-certgen:v1.0
$docker pull willdockerhub/ingress-nginx-controller:v1.0.0
$docker tag willdockerhub/ingress-nginx-controller:v1.0.0 k8s.gcr.io/ingress-nginx/controller:v1.0.0
$docker tag liangjw/kube-webhook-certgen:v1.0 k8s.gcr.io/ingress-nginx/kube-webhook-certgen:v1.0
需要注意的是:
1.node节点需要这镜像,所以可以通过镜像导入来实现
下载节点执行命令
$docker save ef43679c2cae -o /root/ingress-nginx-controller_v1.tar
$docker save 17e55ec30f20 -o /root/ingress-nginx-kube-webhook-certgen_v1.tar
node节点执行命令
$docker tag ef43679c2cae k8s.gcr.io/ingress-nginx/controller:v1.0.0
$docker tag 17e55ec30f20 k8s.gcr.io/ingress-nginx/kube-webhook-certgen:v1.0
完成后运行命令:
[root@k8s-master01 ~]# kubectl get pods -n ingress-nginx
NAME READY STATUS RESTARTS AGE
ingress-nginx-admission-create-f9bqh 0/1 Completed 0 22m
ingress-nginx-admission-patch-nrxft 0/1 Completed 0 22m
ingress-nginx-controller-7fc4b4c548-mqgzz 1/1 Running 0 22m
实验:
http访问

配置:
deployment1.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: deployment1
spec:
replicas: 2
selector:
matchLabels:
name: nginx1
template:
metadata:
labels:
name: nginx1
spec:
containers:
- name: nginx1
image: wangyanglinux/myapp:v1
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
name: nginx-svc1
spec:
ports:
- port: 80
targetPort: 80
protocol: TCP
selector:
name: nginx1
deployment2.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: deployment2
spec:
replicas: 2
selector:
matchLabels:
name: nginx2
template:
metadata:
labels:
name: nginx2
spec:
containers:
- name: nginx2
image: wangyanglinux/myapp:v2
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
name: nginx-svc2
spec:
ports:
- port: 80
targetPort: 80
protocol: TCP
selector:
name: nginx2
上面为DM和SVC的配置
下面为ingress的配置:
[root@k8s-master01 ingress]# cat ingressrule.yaml
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: ingress1
spec:
rules:
- host: www1.k8s-test.com
http:
paths:
- path: /
backend:
serviceName: nginx-svc1
servicePort: 80
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: ingress2
spec:
rules:
- host: www2.k8s-test.com
http:
paths:
- path: /
backend:
serviceName: nginx-svc2
servicePort: 80
实现nginx(ingress)根据不同资源走不同SVC访问
HTTPS访问
1、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/O=nginxsvc"
kubectl create secret tls tls-secret --key tls.key --cert tls.crt
2、Deployment、Service、Ingree yaml文件
[root@k8s-master01 https]# cat deployment1.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: deployment3
spec:
replicas: 2
selector:
matchLabels:
name: nginx3
template:
metadata:
labels:
name: nginx3
spec:
containers:
- name: nginx3
image: wangyanglinux/myapp:v3
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
name: nginx-svc3
spec:
ports:
- port: 80
targetPort: 80
protocol: TCP
selector:
name: nginx3
[root@k8s-master01 https]# cat https.yaml
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: https
spec:
tls:
- hosts:
- www3.k8s-test.com
secretName: tls-secret
rules:
- host: www3.k8s-test.com
http:
paths:
- path: /
backend:
serviceName: nginx-svc3
servicePort: 80
创建好后,使用kubectl get svc -n ingresss-nginx 命令获取443对应的端口
443:30961/TCP
nginx进行BasicAuth
yum install -y httpd
htpasswd -c auth foo
kubectl create secret generic basic-auth --from-file=auth
[root@k8s-master01 basic-auth]# cat ingress-auth.yaml
---
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: auth.k8s-test.com
http:
paths:
- path: /
backend:
serviceName: nginx-svc1
servicePort: 80
Nginx进行重写
Name | Description | Values |
nginx.ingress.kubernetes.io/rewrite-target | 必须将流量重定向到的目标URI | string |
nginx.ingress.kubernetes.io/ssl-redirect | 指示位置部分是否仅可访问SSL(Ingress包含证书时默认为True) | bool |
nginx.ingress.kubernetes.io/force-ssl-redirect | 即使未启用TLS,也强制将重定向到HTTPS | bool |
nginx.ingress.kubernetes.io/app-root | 定义如果在“ /”上下文中,控制器必须重定向的应用程序根 | string |
nginx.ingress.kubernetes.io/use-regex | 指示在Ingress上定义的路径是否使用正则表达式 | bool |
实验目的:

配置:
[root@k8s-master01 redirect]# cat redirect.yaml
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: nginx-test
annotations:
nginx.ingress.kubernetes.io/rewrite-target: https://www3.k8s-test.com:30961
spec:
rules:
- host: redirect.k8s-test.com
http:
paths:
- path: /
backend:
serviceName: nginx-svc1
servicePort: 80
Comments NOTHING