kubernetes RBAC實戰(zhàn) kubernetes 用戶角色訪問控制，dashboard訪問，

sherlock221 發(fā)布于2019-06-28 16:08 / 1739人閱讀

摘要：這個用戶或者組用于后面的角色綁定使用生成的證書就會生成下面的文件校驗證書生成文件已經(jīng)生成了，我們可以直接利用這個文件，省的自己再去配置集群參數(shù)設(shè)置客戶端認(rèn)證參數(shù)設(shè)置上下文參數(shù)設(shè)置莫認(rèn)上下文以上執(zhí)行一個步驟就可以看一下的變化。

kubernetes RBAC實戰(zhàn) 環(huán)境準(zhǔn)備

先用kubeadm安裝好kubernetes集群，kubernetes1.8.2安裝包 | kubernetes1.9.2安裝包好用又方便，服務(wù)周到，童叟無欺

本文目的，讓名為devuser的用戶只能有權(quán)限訪問特定namespace下的pod

命令行kubectl訪問 安裝cfssl

此工具生成證書非常方便, pem證書與crt證書,編碼一致可直接使用

wget https://pkg.cfssl.org/R1.2/cfssl_linux-amd64
chmod +x cfssl_linux-amd64
mv cfssl_linux-amd64 /bin/cfssl

wget https://pkg.cfssl.org/R1.2/cfssljson_linux-amd64
chmod +x cfssljson_linux-amd64
mv cfssljson_linux-amd64 /bin/cfssljson

wget https://pkg.cfssl.org/R1.2/cfssl-certinfo_linux-amd64
chmod +x cfssl-certinfo_linux-amd64
mv cfssl-certinfo_linux-amd64 /bin/cfssl-certinfo

簽發(fā)客戶端證書

根據(jù)ca證書與么鑰簽發(fā)用戶證書
根證書已經(jīng)在/etc/kubernetes/pki目錄下了

[root@master1 ~]# ls /etc/kubernetes/pki/
apiserver.crt                 ca-config.json  devuser-csr.json    front-proxy-ca.key      sa.pub
apiserver.key                 ca.crt          devuser-key.pem     front-proxy-client.crt
apiserver-kubelet-client.crt  ca.key          devuser.pem         front-proxy-client.key
apiserver-kubelet-client.key  devuser.csr     front-proxy-ca.crt  sa.key

注意以下幾個文件： ca.crt ca.key ca-config.json devuser-csr.json

創(chuàng)建ca-config.json文件

cat > ca-config.json <
創(chuàng)建devuser-csr.json文件：
k8s的用戶名就是從CN上獲取的。 組是從O上獲取的。這個用戶或者組用于后面的角色綁定使用
cat > devuser-csr.json <
生成user的證書：
$ cfssl gencert -ca=ca.crt -ca-key=ca.key -config=ca-config.json -profile=kubernetes devuser-csr.json | cfssljson -bare devuser
就會生成下面的文件：
devuser.csr  devuser-key.pem  devuser.pem
校驗證書
# cfssl-certinfo -cert kubernetes.pem
生成config文件
kubeadm已經(jīng)生成了admin.conf，我們可以直接利用這個文件，省的自己再去配置集群參數(shù)
$  cp /etc/kubernetes/admin.conf devuser.kubeconfig
設(shè)置客戶端認(rèn)證參數(shù):
kubectl config set-credentials devuser 
--client-certificate=/etc/kubernetes/ssl/devuser.pem 
--client-key=/etc/kubernetes/ssl/devuser-key.pem 
--embed-certs=true 
--kubeconfig=devuser.kubeconfig
設(shè)置上下文參數(shù)：
kubectl config set-context kubernetes 
--cluster=kubernetes 
--user=devuser 
--namespace=kube-system 
--kubeconfig=devuser.kubeconfig
設(shè)置莫認(rèn)上下文：
kubectl config use-context kubernetes --kubeconfig=devuser.kubeconfig
以上執(zhí)行一個步驟就可以看一下 devuser.kubeconfig的變化。里面最主要的三個東西

cluster: 集群信息，包含集群地址與公鑰
user: 用戶信息，客戶端證書與私鑰，正真的信息是從證書里讀取出來的，人能看到的只是給人看的。
context: 維護一個三元組，namespace cluster 與 user

創(chuàng)建角色
創(chuàng)建一個叫pod-reader的角色
[root@master1 ~]# cat pod-reader.yaml
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  namespace: kube-system
  name: pod-reader
rules:
- apiGroups: [""] # "" indicates the core API group
  resources: ["pods"]
  verbs: ["get", "watch", "list"]
kubectl create -f pod-reader.yaml
綁定用戶
創(chuàng)建一個角色綁定，把pod-reader角色綁定到 devuser上
[root@master1 ~]# cat devuser-role-bind.yaml
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: read-pods
  namespace: kube-system
subjects:
- kind: User
  name: devuser   # 目標(biāo)用戶
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: Role
  name: pod-reader  # 角色信息
  apiGroup: rbac.authorization.k8s.io
kubectl create -f devuser-role-bind.yaml
使用新的config文件
$ rm .kube/config && cp devuser.kubeconfig .kube/config
效果, 已經(jīng)沒有別的namespace的權(quán)限了，也不能訪問node信息了：
[root@master1 ~]# kubectl get node
Error from server (Forbidden): nodes is forbidden: User "devuser" cannot list nodes at the cluster scope

[root@master1 ~]# kubectl get pod -n kube-system
NAME                                       READY     STATUS    RESTARTS   AGE
calico-kube-controllers-55449f8d88-74x8f   1/1       Running   0          8d
calico-node-clpqr                          2/2       Running   0          8d
kube-apiserver-master1                     1/1       Running   2          8d
kube-controller-manager-master1            1/1       Running   1          8d
kube-dns-545bc4bfd4-p6trj                  3/3       Running   0          8d
kube-proxy-tln54                           1/1       Running   0          8d
kube-scheduler-master1                     1/1       Running   1          8d

[root@master1 ~]# kubectl get pod -n default
Error from server (Forbidden): pods is forbidden: User "devuser" cannot list pods in the namespace "default": role.rbac.authorization.k8s.io "pod-reader" not found
dashboard訪問
service account原理
k8s里面有兩種用戶，一種是User，一種就是service account，User給人用的，service account給進程用的，讓進程有相關(guān)的權(quán)限。
如dasboard就是一個進程，我們就可以創(chuàng)建一個service account給它，讓它去訪問k8s。
我們看一下是如何把admin權(quán)限賦給dashboard的：
╰─?  cat dashboard-admin.yaml
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: kubernetes-dashboard
  labels:
    k8s-app: kubernetes-dashboard
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: kubernetes-dashboard
  namespace: kube-system
把 kubernetes-dashboard 這個ServiceAccount綁定到cluster-admin這個ClusterRole上，這個cluster role非常牛逼，啥權(quán)限都有
[root@master1 ~]# kubectl describe clusterrole cluster-admin -n kube-system
Name:         cluster-admin
Labels:       kubernetes.io/bootstrapping=rbac-defaults
Annotations:  rbac.authorization.kubernetes.io/autoupdate=true
PolicyRule:
  Resources  Non-Resource URLs  Resource Names  Verbs
  ---------  -----------------  --------------  -----
             [*]                []              [*]
  *.*        []                 []              [*]
而創(chuàng)建dashboard時創(chuàng)建了這個service account:
apiVersion: v1
kind: ServiceAccount
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system
然后deployment里指定service account
      volumes:
      - name: kubernetes-dashboard-certs
        secret:
          secretName: kubernetes-dashboard-certs
      - name: tmp-volume
        emptyDir: {}
      serviceAccountName: kubernetes-dashboard
更安全的做法
[root@master1 ~]# cat admin-token.yaml
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
  name: admin
  annotations:
    rbac.authorization.kubernetes.io/autoupdate: "true"
roleRef:
  kind: ClusterRole
  name: cluster-admin
  apiGroup: rbac.authorization.k8s.io
subjects:
- kind: ServiceAccount
  name: admin
  namespace: kube-system
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: admin
  namespace: kube-system
  labels:
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
[root@master1 ~]# kubectl get secret -n kube-system|grep admin
admin-token-7rdhf                        kubernetes.io/service-account-token   3         14m
[root@master1 ~]# kubectl describe secret admin-token-7rdhf -n kube-system
Name:         admin-token-7rdhf
Namespace:    kube-system
Labels:       
Annotations:  kubernetes.io/service-account.name=admin
              kubernetes.io/service-account.uid=affe82d4-d10b-11e7-ad03-00163e01d684

Type:  kubernetes.io/service-account-token

Data
====
ca.crt:     1025 bytes
namespace:  11 bytes
token:      eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJrdWJlcm5ldGVzL3NlcnZpY2VhY2NvdW50Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9uYW1lc3BhY2UiOiJrdWJlLXN5c3RlbSIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VjcmV0Lm5hbWUiOiJhZG1pbi10b2tlbi03cmRoZiIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VydmljZS1hY2NvdW50Lm5hbWUiOiJhZG1pbiIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VydmljZS1hY2NvdW50LnVpZCI6ImFmZmU4MmQ0LWQxMGItMTFlNy1hZDAzLTAwMTYzZTAxZDY4NCIsInN1YiI6InN5c3RlbTpzZXJ2aWNlYWNjb3VudDprdWJlLXN5c3RlbTphZG1pbiJ9.jSfQhFsY7V0ZmfqxM8lM_UUOoUhI86axDSeyVVtldSUY-BeP2Nw4q-ooKGJTBBsrOWvMiQePcQxJTKR1K4EIfnA2FOnVm4IjMa40pr7-oRVY37YnR_1LMalG9vrWmqFiqIsKe9hjkoFDuCaP7UIuv16RsV7hRlL4IToqmJMyJ1xj2qb1oW4P1pdaRr4Pw02XBz9yBpD1fs-lbwheu1UKcEnbHS_0S3zlmAgCrpwDFl2UYOmgUKQVpJhX4wBRRQbwo1Sn4rEFVI1NIa9l_lM7Mf6YEquLHRu3BCZTdu9YfY9pevQz4OfHE0NOvDIqmGRL8Z9kPADAXbljWzcD1m1xCQ
用此token在界面上登錄即可