1. 概述
Kubernetes关于服务的暴露主要是通过NodePort方式，通过绑定主机的某个端口,然后进行pod的请求转发和负载均衡，但这种方式下缺陷是
Service可能有很多个，如果每个都绑定一个node主机端口的话，主机需要开放外围一堆的端口进行服务调用，管理混乱。
无法应用很多公司要求的防火墙规则
理想的方式是通过一个外部的负载均衡器，绑定固定的端口，比如80,然后根据域名或者服务名向后面的Service ip转发,Nginx很好的解决了这个需求，但问题是如果有新的服务加入，如何去修改Nginx的配置，并且加载这些配置？ Kubernetes给出的方案就是Ingress,Ingress包含了两大主件Ingress Controller和Ingress.
Ingress解决的是新的服务加入后，域名和服务的对应问题，基本上是一个ingress的对象，通过yaml进行创建和更新进行加载。
Ingress Controller是将Ingress这种变化生成一段Nginx的配置，然后将这个配置通过Kubernetes API写到Nginx的Pod中，然后reload.
2. 配置
2.1 默认路由
生成一个默认的后端，如果遇到解析不到的URL就转发到默认后端页面。
[root@k8s-master ingress]# 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
port: 8080
scheme: HTTP
initialDelaySeconds: 30
timeoutSeconds: 5
ports:
- containerPort: 8080
resources:
limits:
cpu: 10m
memory: 20Mi
requests:
cpu: 10m
memory: 20Mi
---
apiVersion: v1
kind: 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
2.2 部署Ingress Controller
具体文件可以参考官方的
https://github.com/kubernetes/ingress/blob/master/examples/daemonset/nginx/nginx-ingress-daemonset.yaml
[root@k8s-master ingress]# cat nginx-ingress-controller.yaml
apiVersion: v1
kind: ReplicationController
metadata:
name: nginx-ingress-lb
labels:
name: nginx-ingress-lb
namespace: kube-system
spec:
replicas: 1
template:
metadata:
labels:
name: nginx-ingress-lb
annotations:
prometheus.io/port: '10254'
prometheus.io/scrape: 'true'
spec:
terminationGracePeriodSeconds: 60
hostNetwork: true
containers:
- image: gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.7
name: nginx-ingress-lb
readinessProbe:
httpGet:
path: /healthz
port: 10254
scheme: HTTP
livenessProbe:
httpGet:
path: /healthz
port: 10254
scheme: HTTP
initialDelaySeconds: 10
timeoutSeconds: 1
ports:
- containerPort: 80
hostPort: 80
- containerPort: 443
hostPort: 443
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
- name: KUBERNETES_MASTER
value: http://192.168.0.105:8080
args:
- /nginx-ingress-controller
- --default-backend-service=$(POD_NAMESPACE)/default-http-backend
- --apiserver-host=http://192.168.0.105:8080
曾经出现的问题是，启动后pod总是在CrashLoopBack的状态，通过logs一看发现nginx-ingress-controller的启动总是去连接apiserver内部集群ip的443端口，导致因为安全问题不让启动，后来在args里面加入
- --apiserver-host=http://192.168.0.105:8080
2.3 配置ingress
[root@k8s-master ingress]# cat dashboard-weblogic.yaml
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: dashboard-weblogic-ingress
namespace: kube-system
spec:
rules:
- host: helloworld.eric
http:
paths:
- path: /console
backend:
serviceName: helloworldsvc
servicePort: 7001
- path: /
backend:
serviceName: kubernetes-dashboard
servicePort: 80
理解如下:
host指虚拟出来的域名，具体地址(我理解应该是Ingress-controller那台Pod所在的主机的地址)应该加入/etc/hosts中,这样所有去helloworld.eric的请求都会发到nginx
path:/console匹配后面的应用路径
servicePort主要是定义服务的时候的端口，不是NodePort.
path:/ 匹配后面dashboard应用的路径,以前通过访问master节点8080/ui进入dashboard的，但dashboard其实是部署在minion节点中，实际是通过某个路由语句转发过去而已。
2.4 部署Dashbaord
[root@k8s-master ~]# cat kubernetes-dashboard.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
# Keep the name in sync with image version and
# gce/coreos/kube-manifests/addons/dashboard counterparts
name: kubernetes-dashboard-latest
namespace: kube-system
spec:
replicas: 1
template:
metadata:
labels:
k8s-app: kubernetes-dashboard
version: latest
kubernetes.io/cluster-service: "true"
spec:
containers:
- name: kubernetes-dashboard
image: gcr.io/google_containers/kubernetes-dashboard-amd64:v1.5.1
resources:
# keep request = limit to keep this container in guaranteed class
limits:
cpu: 100m
memory: 50Mi
requests:
cpu: 100m
memory: 50Mi
ports:
- containerPort: 9090
args:
- --apiserver-host=http://192.168.0.105:8080
livenessProbe:
httpGet:
path: /
port: 9090
initialDelaySeconds: 30
timeoutSeconds: 30
---
kind: Service
metadata:
name: kubernetes-dashboard
namespace: kube-system
labels:
k8s-app: kubernetes-dashboard
kubernetes.io/cluster-service: "true"
spec:
selector:
k8s-app: kubernetes-dashboard
ports:
- port: 80
targetPort: 9090
2.5 测试
访问http://helloworld.eric/console 出现dashboard
