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Kubernetes的负载均衡问题(Nginx Ingress)
Kubernetes关于服务的暴露主要是通过NodePort方式,通过绑定minion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.
具体实现如下:
1.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.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
这里贴一个我的
[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
后成功启动.
3.配置ingress
配置如下
[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,dashboard真实路径如下:
而yaml文件是
[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
所以访问192.168.51.5:9090端口就会出现dashboard
4.测试
Ok,一切就绪,装逼开始
访问http://helloworld.eric/console
访问http://helloword.eric/ 出现dashboard
5.配置TLS SSL访问
TLS的配置相当于WebLogic中证书的配置,配置过程如下
- 证书生成
# 生成 CA 自签证书 mkdir cert && cd cert openssl genrsa -out ca-key.pem 2048 openssl req -x509 -new -nodes -key ca-key.pem -days 10000 -out ca.pem -subj "/CN=kube-ca" # 编辑 openssl 配置 cp /etc/pki/tls/openssl.cnf . vim openssl.cnf # 主要修改如下 [req] req_extensions = v3_req # 这行默认注释关着的 把注释删掉 # 下面配置是新增的 [ v3_req ] basicConstraints = CA:FALSE keyUsage = nonRepudiation, digitalSignature, keyEncipherment subjectAltName = @alt_names [alt_names] DNS.1 = helloworld.eric #DNS.2 = kibana.mritd.me # 生成证书 openssl genrsa -out ingress-key.pem 2048 openssl req -new -key ingress-key.pem -out ingress.csr -subj "/CN=helloworld.eric" -config openssl.cnf openssl x509 -req -in ingress.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out ingress.pem -days 365 -extensions v3_req -extfile openssl.cnf
需要注意的是DNS需要修改成自己的host名,然后在配置csr证书请求的时候需要将域名或者访问名带入subj,比如
-subj "/CN=helloworld.eric"
- 创建secret
kubectl create secret tls ingress-secret --namespace=kube-system --key cert/ingress-key.pem --cert cert/ingress.pem
- 修改Ingress文件启用证书
[root@k8s-master ingress]# cat tls-weblogic.yaml apiVersion: extensions/v1beta1 kind: Ingress metadata: name: dashboard-weblogic-ingress namespace: kube-system spec: tls: - hosts: - helloworld.eric secretName: ingress-secret rules: - host: helloworld.eric http: paths: - path: /console backend: serviceName: helloworldsvc servicePort: 7001 - path: / backend: serviceName: kubernetes-dashboard servicePort: 80
- 测试
然后访问helloworld.eric/console,会自动转到https页面,同时查看证书并加入授信列表,可见
访问helloworld.eric
Kubernetes的负载均衡问题(Nginx Ingress)