Kubernetes使用Nginx Ingress暴露Dashboard

Kubernetes使用Nginx Ingress暴露Dashboard

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1. 环境说明

• 可用的kubernetes集群
• 可用的nginx ingress controller
• 可用的dashboard

关于kubernetes、dashboard和nginx ingress在前面文章中，已有介绍。
《centos7使用kubeadm安装kubernetes 1.11版本多主高可用》
《kubernetes 1.11配置使用nginx ingress》
也能够使用helm快速搭建nginx ingress和dashboard。
stable/kubernetes-dashboard
stable/nginx-ingress

2. 成功要点

ingress配置啥的这里不详细介绍 。关于暴露dashboard成功的关键，在于新版本dashboard默认使用https提供服务。因此，在ingress中要配置以下annotations参数。

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    nginx.ingress.kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/secure-backends: "true"
    nginx.ingress.kubernetes.io/ssl-passthrough: "true"

3. 为何

而为何是这个nginx.ingress.kubernetes.io前缀呢？

来查查nginx ingress的service，是否是有这个metadata：

[root@lab1 gitlab]# kubectl get svc -n nginx-ingress 
NAME                            TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                   AGE
nginx-ingress-controller        ClusterIP   10.105.201.166   <none>        80/TCP,443/TCP,2222/TCP   23h
nginx-ingress-default-backend   ClusterIP   10.110.35.3      <none>        80/TCP                    23h
[root@lab1 gitlab]# kubectl get svc -n nginx-ingress  nginx-ingress-controller  -o yaml
apiVersion: v1
kind: Service
metadata:
  creationTimestamp: 2018-09-19T09:54:51Z
  labels:
    app: nginx-ingress
    chart: nginx-ingress-0.9.5
    component: controller
    heritage: Tiller
    release: nginx-ingress
  name: nginx-ingress-controller
  namespace: nginx-ingress

那咱们想固然的尝试加上kubernetes.io/ingress.class: nginx

[root@lab1 gitlab]# kubectl edit svc -n nginx-ingress  nginx-ingress-controller 
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: v1
kind: Service
metadata:
  annotations:
    kubernetes.io/ingress.class: nginx

再去dashboard的ingress配置修改为这个：

[root@lab1 templates]# kubectl get ing -n kube-system
NAME                             HOSTS             ADDRESS   PORTS     AGE
dashboard-kubernetes-dashboard   k8s.linuxba.com             80, 443   48m
[root@lab1 templates]# kubectl edit ing -n kube-system dashboard-kubernetes-dashboard
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    kubernetes.io/ingress.class: nginx
    kubernetes.io/secure-backends: "true"
    kubernetes.io/ssl-passthrough: "true"

而后发现，dashboard访问不了了，说明annotations没有生效。那看来service这里的annotations不是决定性因素。

那咱们来分析下，最后生效的是nginx-ingress-controller里的程序解析的，那试试查他的程序运行命令或者帮助：

[root@lab4 ~]# find /var/lib/docker -name nginx-ingress-controller
/var/lib/docker/overlay2/2744ab879932e0ebc522a5f2bdc78ab51742c88d13d1ba99fb1fa8601a07ea43/diff/nginx-ingress-controller
/var/lib/docker/overlay2/63d22e69065b1e49beb4ac91e91106c8e4bab204afc9912304204619cbe7e443/diff/nginx-ingress-controller
^C
[root@lab4 ~]# /var/lib/docker/overlay2/2744ab879932e0ebc522a5f2bdc78ab51742c88d13d1ba99fb1fa8601a07ea43/diff/nginx-ingress-controller --help|more
Usage of :
      --alsologtostderr                   log to standard error as well as files
      --annotations-prefix string         Prefix of the Ingress annotations specific to the NGINX controller. (default "nginx.ingress.kubernetes.io")

果真发现了决定性参数--annotations-prefix。

4. 小结

原来一直以来，我忽视掉了这个关键参数。固然，有人会说，像linux同样，用到那么多命令，那么多参数，怎么可能记得住，都看过。因此，我以为一项很重要的习惯或者技能，是学会去摸索，去实践排查，这样咱们会的东西，其实比表面看起来要多得多。

参考资料：
[1] https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/