原文：kubernetes学习笔记之十:RBAC(一) - 百衲本 - 博客园 (cnblogs.com)
阅读目录
第一章、RBAC介绍
在Kubernetes中，授权有ABAC（基于属性的访问控制）、RBAC（基于角色的访问控制）、Webhook、Node、AlwaysDeny（一直拒绝）和AlwaysAllow（一直允许）这6种模式。从1.6版本起，Kubernetes 默认启用RBAC访问控制策略。从1.8开始，RBAC已作为稳定的功能。通过设置–authorization-mode=RBAC，启用RABC。在RABC API中，通过如下的步骤进行授权：1）定义角色：在定义角色时会指定此角色对于资源的访问控制的规则；2）绑定角色：将主体与角色进行绑定，对用户进行访问授权。
1、 角色和集群角色
在RBAC API中，角色包含代表权限集合的规则。在这里，权限只有被授予，而没有被拒绝的设置。在Kubernetes中有两类角色，即普通角色和集群角色。可以通过Role定义在一个命名空间中的角色，或者可以使用ClusterRole定义集群范围的角色。一个角色只能被用来授予访问单一命令空间中的资源。
集群角色(ClusterRole)能够被授予如下资源的权限：
集群范围的资源（类似于Node）
非资源端点（类似于”/healthz”）
集群中所有命名空间的资源（类似Pod）
2、角色绑定和集群角色绑定
角色绑定用于将角色与一个或一组用户进行绑定，从而实现将对用户进行授权的目的。主体分为用户、组和服务帐户。角色绑定也分为角色普通角色绑定和集群角色绑定。角色绑定只能引用同一个命名空间下的角色。
角色绑定也可以通过引用集群角色授予访问权限，当主体对资源的访问仅限与本命名空间，这就允许管理员定义整个集群的公共角色集合，然后在多个命名空间中进行复用。
集群角色可以被用来在集群层面和整个命名空间进行授权。
3、资源
在Kubernets中，主要的资源包括：Pods、Nodes、Services、Deployment、Replicasets、Statefulsets、Namespace、Persistents、Secrets和ConfigMaps等。另外，有些资源下面存在子资源，例如：Pod下就存在log子资源
4、主体
RBAC授权中的主体可以是组，用户或者服务帐户。用户通过字符串表示，比如“alice”、 “bob@example.com”等，具体的形式取决于管理员在认证模块中所配置的用户名。system:被保留作为用来Kubernetes系统使用，因此不能作为用户的前缀。组也有认证模块提供，格式与用户类似。
第二章、简单示例
1、使用RoleBanding将用户绑定到Role上
查看命令帮助及格式
[root@k8s-master01 ~]# kubectl create role -h #查看创建role的命令帮助，以及一些简单的示例
[root@k8s-master01 RBAC]# kubectl create role pods-reader --verb=get,list,watch --resource=pods --dry-run -o yaml #通过 -o参数导出yaml格式，可以大致看到Role是如何定义的
[root@k8s-master01 RBAC]# cat role-****demo.yaml #最后完成的yaml文件如下**
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
name: pods-reader namespace: default #名称空间名称
rules: - apiGroups: - "" resources: #包含哪些资源 - pods
verbs: #对以上资源允许进行哪些操作 - get
- list - watch
创建role
[root@k8s-master01 RBAC]# kubectl apply -f role-****demo.yaml** role.rbac.authorization.k8s.io "pods-reader" created
[root@k8s****-master01 RBAC]# kubectl get role #查看role的信息 NAME AGE
pods-reader 8s
[root@k8s****-master01 RBAC]# kubectl describe role pods-reader #查看pods-****reader 的详细信息 Name: pods-reader
Labels: <none> Annotations: kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"rbac.authorization.k8s.io/v1","kind":"Role","metadata":{"annotations":{},"name":"pods-reader","namespace":"default"},"rules":[{"apiGroup...
PolicyRule:
Resources Non-Resource URLs Resource Names Verbs --------- ----------------- -------------- ----- pods [] [] [get list watch]
#
Resources：资源类别，表示对该资源类别下的所有资源进行操作
Non****-****Resource URLs：非资源URL，对某些资源进行某种特殊操作的存在
Resource Names：对资源类别下某个或多个资源进行操作
Verbs：操作的类型
** 创建一个RoleBinding，将用户qiangungun(该用户在上一章节serviceaccount中已经被创建)绑定到pods-reader 这个role上去**
[root@k8s-master01 ~]# kubectl create rolebinding -****h #查看命令帮助 ** kubectl create rolebinding qiangungun-read-pods --role=pods-reader --user=qiangungun --dry-run -o yaml #创建名称为qiangungun-read-pods的rolebinding，绑定到名称为pods-reader的role上
[root@k8s****-master01 RBAC]# cat rolebinding-****demo.yaml apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: qiangungun-read-pods
roleRef: #role引用，表示引用哪个role
apiGroup: rbac.authorization.k8s.io
kind: Role
name: pods-reader
subjects: #动作的执行主题 - apiGroup: rbac.authorization.k8s.io
kind: User
name: qiangungun
[root@k8s-master01 RBAC]# kubectl describe rolebinding qiangungun-read-pods
Name: qiangungun-read-pods
Labels: <none> Annotations: kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"rbac.authorization.k8s.io/v1","kind":"RoleBinding","metadata":{"annotations":{},"name":"qiangungun-read-pods","namespace":"default"},"ro...
Role:
Kind: Role
Name: pods-reader
Subjects:
Kind Name Namespace ---- ---- --------- User qiangungun
验证操作
[root@k8s-master01 RBAC]# kubectl config use-****context qiangungun@kubernetes #前后当前上下文到qiangungun用户** Switched to context "qiangungun@kubernetes".
[root@k8s****-master01 RBAC]# kubectl get pods #获取当前名称空间的pod信息，可以看到能够正常显示 NAME READY STATUS RESTARTS AGE
myapp-deploy-5cfd895984-262kz 1/1 Running 0 3d
myapp-deploy-5cfd895984-7whdn 1/1 Running 0 3d
myapp-deploy-5cfd895984-lg8sh 1/1 Running 0 3d
myapp-deploy-5cfd895984-m7h5j 1/1 Running 0 3d
myapp-deploy-5cfd895984-zd9cm 1/1 Running 0 3d
[root@k8s****-master01 RBAC]# kubectl get pods -n kube-****system #查看其它空间pod的信息，可以看到提示没有权限，即验证RoleBanding的权限只对当前的名称空间生效 Error from server (Forbidden): pods is forbidden: User "qiangungun" cannot list pods in the namespace "kube-system"
2、使用ClusterRoleBanding将用户绑定到ClusterRole上
创建一个ClusterRole
[root@k8s-master01 RBAC]# kubectl config use-context kubernetes-****admin@kubernetes #切换上下文** Switched to context "kubernetes-admin@kubernetes".
[root@k8s****-master01 RBAC]# kubectl create clusterrole -h
[root@k8s-master01 RBAC]# kubectl create clusterrole cluster-reader --verb=get,list,watch --resource=pods -o yaml --dry-run
[root@k8s-master01 RBAC]# cat clusterrole-****cluster.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: cluster-reader #ClusterRole属于集群级别，所有不可以定义namespace
rules: - apiGroups: - "" resources: - pods
verbs: - get
- list - watch
[root@k8s****-master01 RBAC]# kubectl apply -f clusterrole-cluster.yaml
[root@k8s-master01 RBAC]# useradd admin
[root@k8s-master01 RBAC]# cp -rp ~/.kube/ /home/admin
[root@k8s-master01 RBAC]# chown -R admin:admin /home/admin
[root@k8s-master01 RBAC]# su - admin
[admin@k8s-master01 ~]kubectl config view
创建一个ClusterRoleBinding,将用户qiangungun绑定到cluster-reader这个ClusterRole上面去
root用户
[admin@k8s-master01 ~]$ kubectl get** pods #admin用户下验证
Error from server (Forbidden): pods is forbidden: User "qiangungun" cannot list pods in the namespace "default" [root@k8s-master01 RBAC]# kubectl create clusterrolebinding -h
[root@k8s-master01 RBAC]# kubectl create clusterrolebinding qiangungun-read-all-pods --clusterrole=cluster-reader --user=qiangungun --dry-run -o yaml #创建名称为qiangungun-read-all-pods的才clusterrolebinding，将名称为cluster-reader的clusterrole绑定到用户名称为qiangungun上
[root@k8s-master01 RBAC]# cat clusterrolebinding-****demo.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
creationTimestamp: null name: qiangungun-read-all-pods
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-reader
subjects: - apiGroup: rbac.authorization.k8s.io
kind: User
name: qiangungun
[root@k8s****-master01 RBAC]# kubectl apply -f clusterrolebinding-demo.yaml
[root@k8s-master01 RBAC]# kubectl describe clusterrolebinding qiangungun-read-all-pods
验证
切换到admin用户终端下
[admin@k8s-master01 ~] kubectl get pods -n ingress-****nginx #可以查看其他空间的pod信息** NAME READY STATUS RESTARTS AGE default-http-backend-66c4fbf5b4-m8d6j 1/1 Running 0 24d
nginx-ingress-controller-64bcff8657-6j4tq 1/1 Running 0 24d
[admin@k8s****-master01 ~]$ kubectl delete pod myapp-deploy-5cfd895984-****262kz #无法删除pod
Error from server (Forbidden): pods "myapp-deploy-5cfd895984-262kz" is forbidden: User "qiangungun" cannot delete pods in the namespace "default"
3、使用RoleBinding绑定ClusterRole
创建一个RoleBinding(ClusterRole使用以及存在的)，并将用户绑定到ClusterRole上
[root@k8s-master01 RBAC]# kubectl delete clusterrolebinding qiangungun-read-all-****pods #为了避免冲突，先将之前的clusterrolebinding删除** clusterrolebinding.rbac.authorization.k8s.io "qiangungun-read-all-pods" deleted
[root@k8s****-master01 RBAC]#kubectl create rolebinding qiangungun-read-pods --clusterrole=cluster-reader --user=qiangungun --dry-run -o yam
[root@k8s-master01 RBAC]# cat rolebinding-cluster-****demo.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: qiangungun-read-pods
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-reader
subjects: - apiGroup: rbac.authorization.k8s.io
kind: User
name: qiangungun
[root@k8s****-master01 RBAC]# kubectl apply -f rolebinding-cluster-****demo.yaml rolebinding.rbac.authorization.k8s.io "qiangungun-read-pods" created
[root@k8s****-master01 RBAC]# kubectl describe rolebinding qiangungun-read-pods
验证：
#admin用户终端下
[admin@k8s-master01 ~] kubectl get pods -n ingress-****nginx #不可用获取其他名称空间的信息 Error from server (Forbidden): pods is forbidden: User "qiangungun" cannot list pods in the namespace "ingres
4、使用RoleBinding绑定集群自带的ClusterRole
[root@k8s-master01 RBAC]# kubectl get clusterrole #查看当前集群存在的clusterrole
[root@k8s-master01 RBAC]# kubectl create rolebinding default-ns-admin --clusterrole=admin --user=qiangungun --dry-run -o yaml #将qiangungun用户绑定到名称为admin的clusterrole上，可以使用get查看admin的配置
[root@k8s-master01 RBAC]# cat rolebinding-cluster-admin-****demo.yaml**
piVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: default-ns-admin namespace: default roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: admin
subjects: - apiGroup: rbac.authorization.k8s.io
kind: User
name: qiangungun
[root@k8s****-master01 RBAC]# kubectl apply -f rolebinding-cluster-admin-demo.yaml
[root@k8s-master01 RBAC]# kubectl describe rolebinding default-ns-admin
验证
admin用户终端下
[admin@k8s-master01 ~] kubectl delete pod myapp-deploy-5cfd895984-****262kz #可以删除当前名称空间的pod** pod "myapp-deploy-5cfd895984-262kz" deleted
[admin@k8s****-master01 ~] kubectl delete deployment nginx-****deploy #可以删除当前名称空间的其他资源，如deployment deployment.extensions "nginx-deploy" deleted
[admin@k8s****-master01 ~]$ kubectl get pods -n kube-****system #对其名称空间没有任何权限 Error from server (Forbidden): pods is forbidden: User "qiangungun" cannot list pods in the namespace "kube-system"
第三章、Role、CluseterRole、RoleBinding、ClusterRoleBinding在系统的相关联系
[root@k8s-master01 RBAC]# kubectl get** clusterrolebinding #查看集群中的clusterrolebingding NAME AGE
cluster-admin 31d
......
[root@k8s****-master01 RBAC]# kubectl get clusterrolebinding cluster-admin -o yaml #获取名称为cluster-****admin的clusterrolebingding配置信息 apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
annotations:
rbac.authorization.kubernetes.io/autoupdate: "true" creationTimestamp: 2018-10-30T02:32:22Z
labels:
kubernetes.io/bootstrapping: rbac-defaults
name: cluster-admin
resourceVersion: "103" selfLink: /apis/rbac.authorization.k8s.io/v1/clusterrolebindings/cluster-admin
uid: 07b1d436-dbec-11e8-8969-5254001b07db
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-admin
subjects: - apiGroup: rbac.authorization.k8s.io
kind: Group #类型是一个组
name: system:masters #这个组中包含了kubernetes****-****admin这个用户，而这个用户是默认的当前使用用户
[root@k8s****-****master01 RBAC]# kubectl config view
apiVersion: v1
clusters: - cluster:
certificate-authority-data: REDACTED
server: https://172.16.150.212:6443
name: kubernetes
contexts: - context:
cluster: kubernetes
user: kubernetes-admin #默认使用的当前用户
name: kubernetes-admin@kubernetes - context:
cluster: kubernetes
user: qiangungun
name: qiangungun@kubernetes
current-context: kubernetes-admin@kubernetes #当前的使用sa
kind: Config
preferences: {}
users: - name: kubernetes-admin
user:
client-certificate-data: REDACTED
client-key-data: REDACTED - name: qiangungun
user:
client-certificate-data: REDACTED
client-key-data: REDACTED
[root@k8s****-master01 RBAC]# cd /etc/kubernetes/pki/ [root@k8s-master01 pki]# openssl x509 -in ./apiserver-kubelet-client.crt -text -****noout #查看证书签发的内容
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 3187679453637891293 (0x2c3ce992f3e5d4dd)
Signature Algorithm: sha256WithRSAEncryption
Issuer: CN=kubernetes
Validity
Not Before: Oct 30 02:32:03 2018 GMT
Not After : Oct 30 02:32:03 2019 GMT
Subject: O=system:masters, CN=kube-apiserver-kubelet-client #kubernetes-****admin用户之所以属于system:master这个组，是因为在它的的证书中定义的，O表示组,如果以后我们想一次授权多个用户，可以将这些用户添加至一个组内，然后给这个组授权即可
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
Public-Key: (2048 bit)
.....
#如果RoleBinding或者ClusterRoleBinding的对象是serviceaccount，，那么任意一个pod(spec.serviceAcountName中定义)如果启动时以这个serviceaccount name作为它是以的serviceaccount，那么pod中的应用程序也同时拥有了这个serviceaccount的权限，也就是拥有该serviceaccount绑定的Role或者ClusterRole的权限。系统上一下特殊的pod可能需要做这样的设置，下面我就以集群创建时使用的flannel网络插件为示例讲解
查看flannel的配置
[root@k8s-master01 kubernetes]# cat kube-flannel.yml #flannel的配置文件** --- kind: ClusterRole #定义一个ClusterRole
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: flannel
rules: - apiGroups: - "" resources: - pods
verbs: - get
- apiGroups: - "" resources: - nodes
verbs: - list - watch - apiGroups: - "" resources: - nodes/status
verbs: - patch --- kind: ClusterRoleBinding #定义了一个ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: flannel
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: flannel
subjects: - kind: ServiceAccount
name: flannel namespace: kube-system --- apiVersion: v1
kind: ServiceAccount #定义了一个ServiceAccount
metadata:
name: flannel namespace: kube-system --- kind: ConfigMap
apiVersion: v1
metadata:
name: kube-flannel-cfg namespace: kube-system
labels:
tier: node
app: flannel
data:
cni-conf.json: | { "name": "cbr0", "plugins": [
{ "type": "flannel", "delegate": { "hairpinMode": true, "isDefaultGateway": true }
},
{ "type": "portmap", "capabilities": { "portMappings": true }
}
]
}
net-conf.json: | { "Network": "10.244.0.0/16", "Backend": { "Type": "vxlan" }
} --- ......(以下省略)
查看flannel创建的pod信息
[root@k8s-master01 kubernetes]# kubectl get pod -n kube-****system** NAME READY STATUS RESTARTS AGE
etcd-k8s-master01 1/1 Running 0 32d
kube-apiserver-k8s-master01 1/1 Running 0 32d
kube-controller-manager-k8s-master01 1/1 Running 0 7d
kube-dns-86f4d74b45-72kdh 3/3 Running 0 32d
kube-flannel-ds-amd64-847wt 1/1 Running 0 32d
kube-flannel-ds-amd64-9v9t6 1/1 Running 0 32d
kube-flannel-ds-amd64-k4blq 1/1 Running 0 32d
kube-proxy-8l9tf 1/1 Running 0 32d
kube-proxy-m6pqm 1/1 Running 0 32d
kube-proxy-scj8n 1/1 Running 0 32d
kube-scheduler-k8s-master01 1/1 Running 0 32d
[root@k8s****-master01 kubernetes]# kubectl get pod kube-flannel-ds-amd64-847wt -n kube-system -****o yaml ......(省略)
serviceAccount: flannel
serviceAccountName: flannel #表示当前的pod在启动容器时，运行的进程与APIserver进行通讯的时候，会以serviceAccountName的账号与APIserver进行连接，从而获得该serviceaccount的权限
.....(省略)
