2019独角兽企业重金招聘Python工程师标准>>> 
kubernetes RBAC实战
环境准备
先用kubeadm安装好kubernetes集群，[包地址在此](https://market.aliyun.com/products/56014009/cmxz022571.html#sku=yuncode1657100000) 好用又方便，服务周到，童叟无欺
本文目的，让名为devuser的用户只能有权限访问特定namespace下的pod
命令行kubectl访问
安装cfssl
此工具生成证书非常方便, pem证书与crt证书,编码一致可直接使用 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
签发客户端证书
根据ca证书与么钥签发用户证书
根证书已经在/etc/kubernetes/pki目录下了
[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
注意以下几个文件： `ca.crt ca.key ca-config.json devuser-csr.json`
创建ca-config.json文件
cat > ca-config.json < devuser-csr.json < 校验证书 cfssl-certinfo -cert kubernetes.pem
生成config文件
kubeadm已经生成了admin.conf，我们可以直接利用这个文件，省的自己再去配置集群参数
$ cp /etc/kubernetes/admin.conf devuser.kubeconfig
设置客户端认证参数:
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
设置上下文参数：
kubectl config set-context kubernetes \ --cluster=kubernetes \ --user=devuser \ --namespace=kube-system \ --kubeconfig=devuser.kubeconfig
设置莫认上下文：
kubectl config use-context kubernetes --kubeconfig=devuser.kubeconfig
以上执行一个步骤就可以看一下 devuser.kubeconfig的变化。里面最主要的三个东西
- cluster: 集群信息，包含集群地址与公钥
- user: 用户信息，客户端证书与私钥，正真的信息是从证书里读取出来的，人能看到的只是给人看的。
- context: 维护一个三元组，namespace cluster 与 user
创建角色
创建一个叫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
绑定用户
创建一个角色绑定，把pod-reader角色绑定到 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 # 目标用户 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, 已经没有别的namespace的权限了，也不能访问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访问
service account原理
k8s里面有两种用户，一种是User，一种就是service account，User给人用的，service account给进程用的，让进程有相关的权限。
如dasboard就是一个进程，我们就可以创建一个service account给它，让它去访问k8s。
我们看一下是如何把admin权限赋给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 这个ServiceAccount绑定到cluster-admin这个ClusterRole上，这个cluster role非常牛逼，啥权限都有
[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 --------- ----------------- -------------- ----- [*] [] [*] *.* [] [] [*]
而创建dashboard时创建了这个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在界面上登录即可