k8s核心概念Ingress
2022/1/18 23:41:43
本文主要是介绍k8s核心概念Ingress，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！
1. 什么是 Ingress
通常情况下，service和pod的IP仅可在集群内部访问。集群外部的请求需要通过负载均衡转发到service在Node上暴露的NodePort上，然后再由kube-proxy将其转发给相关的Pod。
而Ingress就是为进入集群的请求提供路由规则的集合，如下图所示
internet
|
[ Ingress ]
--|-----|--
[ Services ]
Ingress可以给service提供集群外部访问的URL、负载均衡、SSL终止、HTTP路由等。为了配置这些Ingress规则，集群管理员需要部署一个Ingress controller，它监听Ingress和service的变化，并根据规则配置负载均衡并提供访问入口。
一个 Ingress controller 是能将一个特定的负载均衡器和 Kubernetes 整合在一起的软件。开源的 NGINX 和 NGINX Plus 有相应的 Ingress controller，GitHub 仓库（https://github.com/nginxinc/kubernetes-ingress)。我自己理解Ingress Controller 实际上是将nginx 和 kubernetes做了一个整合，使得nginx 可以拿到kubernetes 的service 信息，我们启动一个ingressController 之后，在编写对应的rule 即可实现转发以及负载均衡。
可以理解为ingress 是对service进行代理，我们不需要知道service 对pods 暴露的端口等信息，pods 重启service 暴露的端口改变等对于应用无感，应用只和ingress 大交道。
2. 和pod 的关系
ingress 和 pod 通过service 进行关联，ingress 作为统一入口，由service 关联一组pod。
3. Ingress 工作流程
ingress 作为统一的入口，根据请求路径不同转发到后端不同服务。
4. 使用ingress：
1. 部署ingress controller
2. 创建ingress 规则
5. 部署测试
选择官方维护nginx 控制器，实现部署。简单的实现基于不同的域名转发到不同的service。效果如下：
1. 创建nginx 应用，使用service 对外暴露端口
kubectl create deployment nginx --image=nginx kubectl expose deployment nginx --port=80 --type=NodePort
查看svc 以及 相关信息：
[root@k8smaster1 ~]# kubectl get svc -o wide NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 8d <none> nginx NodePort 10.109.175.64 <none> 80:32503/TCP 32m app=nginx
接下来从windows， 通过任何k8s 节点的32503 端口即可访问到nginx。
2. 创建tomcat服务, 并且使用service 对其暴露端口
[root@k8smaster1 ~]# kubectl create deployment tomcat --image=tomcat:8.0.15-jre8 deployment.apps/tomcat created [root@k8smaster1 ~]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx-f89759699-vkf7d 1/1 Running 1 59m tomcat-58767d5b5-f5qwj 1/1 Running 0 8s [root@k8smaster1 ~]# kubectl expose deployment tomcat --port=8080 --type=NodePort service/tomcat exposed [root@k8smaster1 ~]# kubectl get svc -o wide NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 8d <none> nginx NodePort 10.109.175.64 <none> 80:32503/TCP 59m app=nginx tomcat NodePort 10.100.178.25 <none> 8080:30158/TCP 6s app=tomcat
3. 最后service 暴露后的效果如下： 可以从外部通过k8s任意的节点IP+端口访问到指定服务
4. 创建ingress controller
(1) 创建ingress-controller.yaml
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:
hostNetwork: true
# wait up to five minutes for the drain of connections
terminationGracePeriodSeconds: 300
serviceAccountName: nginx-ingress-serviceaccount
nodeSelector:
kubernetes.io/os: linux
containers:
- name: nginx-ingress-controller
image: lizhenliang/nginx-ingress-controller:0.30.0
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 -> 101
runAsUser: 101
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
ports:
- name: http
containerPort: 80
protocol: TCP
- name: https
containerPort: 443
protocol: TCP
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
lifecycle:
preStop:
exec:
command:
- /wait-shutdown
---
apiVersion: v1
kind: LimitRange
metadata:
name: ingress-nginx
namespace: ingress-nginx
labels:
app.kubernetes.io/name: ingress-nginx
app.kubernetes.io/part-of: ingress-nginx
spec:
limits:
- min:
memory: 90Mi
cpu: 100m
type: Container
View Code
(2) 创建相关资源
[root@k8smaster1 ~]# kubectl apply -f ingress-controller.yaml namespace/ingress-nginx created configmap/nginx-configuration created configmap/tcp-services created configmap/udp-services created serviceaccount/nginx-ingress-serviceaccount created clusterrole.rbac.authorization.k8s.io/nginx-ingress-clusterrole created role.rbac.authorization.k8s.io/nginx-ingress-role created rolebinding.rbac.authorization.k8s.io/nginx-ingress-role-nisa-binding created clusterrolebinding.rbac.authorization.k8s.io/nginx-ingress-clusterrole-nisa-binding created deployment.apps/nginx-ingress-controller created limitrange/ingress-nginx created [root@k8smaster1 ~]# kubectl get all -o wide -n ingress-nginx NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES pod/nginx-ingress-controller-766fb9f77-tksqp 0/1 ContainerCreating 0 36s 192.168.13.105 k8snode2 <none> <none> NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR deployment.apps/nginx-ingress-controller 0/1 1 0 36s nginx-ingress-controller lizhenliang/nginx-ingress-controller:0.30.0 app.kubernetes.io/name=ingress-nginx,app.kubernetes.io/part-of=ingress-nginx NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR replicaset.apps/nginx-ingress-controller-766fb9f77 1 1 0 36s nginx-ingress-controller lizhenliang/nginx-ingress-controller:0.30.0 app.kubernetes.io/name=ingress-nginx,app.kubernetes.io/part-of=ingress-nginx,pod-template-hash=766fb9f77
(3) 到k8snode2 节点查看nginx 监听的端口， nginx-controller 实际是启动了一个nginx
[root@k8snode2 ~]# netstat -nltp | grep 80 tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 5852/nginx: master tcp6 0 0 :::80 :::* LISTEN 5852/nginx: master [root@k8snode2 ~]# netstat -nltp | grep 443 tcp 0 0 0.0.0.0:443 0.0.0.0:* LISTEN 5852/nginx: master tcp6 0 0 :::443 :::* LISTEN 5852/nginx: master
5. 编写ingress 规则
(1) 编写 ingress-rule.yaml
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: example-ingress
spec:
rules:
- host: nginx.ingredemo.com
http:
paths:
- path: /
backend:
serviceName: nginx
servicePort: 80
- host: tomcat.ingredemo.com
http:
paths:
- path: /
backend:
serviceName: tomcat
servicePort: 8080
(2) 执行创建并且查看
[root@k8smaster1 ~]# kubectl apply -f ingress-rule.yaml
ingress.networking.k8s.io/example-ingress configured
[root@k8smaster1 ~]# kubectl get ing -o wide
NAME CLASS HOSTS ADDRESS PORTS AGE
example-ingress <none> nginx.ingredemo.com,tomcat.ingredemo.com 80 15h
[root@k8smaster1 ~]# kubectl describe ing example-ingress
Name: example-ingress
Namespace: default
Address:
Default backend: default-http-backend:80 (<error: endpoints "default-http-backend" not found>)
Rules:
Host Path Backends
---- ---- --------
nginx.ingredemo.com
/ nginx:80 (10.244.1.89:80)
tomcat.ingredemo.com
/ tomcat:8080 (10.244.1.92:8080)
Annotations: Events: <none>
6. 测试：
(1) windows 下面配置虚拟的域名:
C:\Windows\System32\drivers\etc\hosts 文件增加如下配置， 注意IP 是自己nginx-controller 所在的节点
192.168.13.105 nginx.ingredemo.com 192.168.13.105 tomcat.ingredemo.com
(2) 访问测试：根据不同域名可以访问到不同的服务
补充： ingress 也可以根据不同的路径分配到不同的service
例如：
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: test
spec:
rules:
- host: foo.bar.com
http:
paths:
- path: /foo
backend:
serviceName: s1
servicePort: 80
- path: /bar
backend:
serviceName: s2
servicePort: 80
上面表示如下结果：
foo.bar.com -> 178.91.123.132 -> / foo s1:80
/ bar s2:80
这篇关于k8s核心概念Ingress的文章就介绍到这儿，希望我们推荐的文章对大家有所帮助，也希望大家多多支持为之网！
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