Kubernetes监控手册05-监控Kubelet

上一篇我们介绍了如何监控Kube-Proxy，Kube-Proxy的/metrics接口没有认证，相对比较容易，这一篇我们介绍一下Kubelet，Kubelet的监控相比Kube-Proxy增加了认证机制，相对更复杂一些。

Kubelet 端口说明

如果你有多台Node节点，可以批量执行 ss -tlnp|grep kubelet 看一下，Kubelet 监听两个固定端口(我的环境，你的环境可能不同)，一个是10248，一个是10250，通过下面的命令可以知道，10248是健康检查的端口：

[root@tt-fc-dev01.nj ~]# ps aux|grep kubelet
root      163490  0.0  0.0  12136  1064 pts/1    S+   13:34   0:00 grep --color=auto kubelet
root      166673  3.2  1.0 3517060 81336 ?       Ssl  Aug16 4176:52 /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --config=/var/lib/kubelet/config.yaml --hostname-override=10.206.0.16 --network-plugin=cni --pod-infra-container-image=registry.aliyuncs.com/google_containers/pause:3.6

[root@tt-fc-dev01.nj ~]# cat /var/lib/kubelet/config.yaml | grep 102
healthzPort: 10248

[root@tt-fc-dev01.nj ~]# curl localhost:10248/healthz
ok

我们再看一下 10250，10250实际是Kubelet的默认端口，/metrics 接口就是在这个端口暴露的，我们请求一下：

[root@tt-fc-dev01.nj ~]# curl localhost:10250/metrics
Client sent an HTTP request to an HTTPS server.

[root@tt-fc-dev01.nj ~]# curl https://localhost:10250/metrics
curl: (60) SSL certificate problem: self signed certificate in certificate chain
More details here: https://curl.haxx.se/docs/sslcerts.html

curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.
[root@tt-fc-dev01.nj ~]# curl -k https://localhost:10250/metrics
Unauthorized

-k 表示不校验SSL证书是否正确，最后的命令可以看到返回了 Unauthorized，表示认证失败，我们先来解决一下认证问题。认证是 Kubernetes 的一个知识点，这里先不展开（你需要Google一下了解基本常识），直接实操。

认证信息

下面的信息可以保存为 auth.yaml，创建了 ClusterRole、ServiceAccount、ClusterRoleBinding。

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: categraf-daemonset
rules:
- apiGroups:
  - ""
  resources:
  - nodes/metrics
  - nodes/stats
  - nodes/proxy
  verbs:
  - get
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: categraf-daemonset
  namespace: flashcat
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: categraf-daemonset
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: categraf-daemonset
subjects:
- kind: ServiceAccount
  name: categraf-daemonset
  namespace: flashcat

ClusterRole是个全局概念，不属于任一个namespace，定义了很多权限点，都是读权限，监控嘛，读权限就可以了，ServiceAccount则是namespace颗粒度的一个概念，这里我们创建了一个名为categraf-daemonset的ServiceAccount，然后绑定到ClusterRole上面，具备了各种查询权限。apply一下即可：

[work@tt-fc-dev01.nj yamls]$ kubectl apply -f auth.yaml
clusterrole.rbac.authorization.k8s.io/categraf-daemonset created
serviceaccount/categraf-daemonset created
clusterrolebinding.rbac.authorization.k8s.io/categraf-daemonset created

[work@tt-fc-dev01.nj yamls]$ kubectl get ClusterRole | grep categraf-daemon
categraf-daemonset                                                     2022-11-14T03:53:54Z
[work@tt-fc-dev01.nj yamls]$ kubectl get sa -n flashcat
NAME                 SECRETS   AGE
categraf-daemonset   1         90m
default              1         4d23h
[work@tt-fc-dev01.nj yamls]$ kubectl get ClusterRoleBinding -n flashcat | grep categraf-daemon
categraf-daemonset ClusterRole/categraf-daemonset 91m

测试权限

上面的命令行输出可以看出来，我们已经成功创建了 ServiceAccount，把ServiceAccount的内容打印出来看一下：

[root@tt-fc-dev01.nj qinxiaohui]# kubectl get sa categraf-daemonset -n flashcat -o yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"v1","kind":"ServiceAccount","metadata":{"annotations":{},"name":"categraf-daemonset","namespace":"flashcat"}}
  creationTimestamp: "2022-11-14T03:53:54Z"
  name: categraf-daemonset
  namespace: flashcat
  resourceVersion: "120570510"
  uid: 22f5a785-871c-4454-b82e-12bf104450a0
secrets:
- name: categraf-daemonset-token-7mccq

注意最后两行，这个ServiceAccount实际是关联了一个Secret，我们再看看这个Secret的内容：

[root@tt-fc-dev01.nj qinxiaohui]# kubectl get secret categraf-daemonset-token-7mccq -n flashcat -o yaml
apiVersion: v1
data:
  ca.crt: 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