RBAC引入了4个顶级资源对象：Role、ClusterRole：角色，用于指定一组权限；RoleBinding、ClusterRoleBinding：角色绑定，用于将角色（权限）赋予给对象
咱们通过Role可以配置命名空间下资源的访问权限，例如，pod，service，deployment等资源是否可以修改，删除等权限；Role只能对命名空间内的资源进行授权，需要指定nameapce
ClusterRole是整个kubernetes下的资源的访问权限的控制，跨namespaces的范围资源、非资源类型进行授权
我当前app整个命名空间下有一些pod，我们以app这个命名空间，创建一个xiaom的用户，这个用户只能app这个命名空间下的Pod，Deployment的资源，其他的资源没权限更改
[root@k8s-master1 RBAC]# kubectl get pods -n app -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
dsf-67b6bd65c9-44rl4 2/2 Running 16 (3h15m ago) 25d 10.10.135.218 k8s-master3 <none> <none>
ingress-nginx-controller-74974c55bd-2bw2r 1/1 Running 6 (20h ago) 2d1h 192.168.21.100 k8s-node1 <none> <none>
ingress-nginx-controller-74974c55bd-j24mf 1/1 Running 10 (3h15m ago) 31d 192.168.21.122 k8s-master3 <none> <none>
nginx-55c7d65db4-z4rcc 1/1 Running 4 (20h ago) 2d1h 10.10.36.96 k8s-node1 <none> <none>
postgres-sonar-5b9d94cd6b-965tk 1/1 Running 2 (3h15m ago) 2d1h 10.10.135.221 k8s-master3 <none> <none>
tomcat-657677ffb5-2nrfc 1/1 Running 8 (3h15m ago) 26d 10.10.135.222 k8s-master3 <none> <none>
Role的配置示例：
[root@k8s-master1 app]# kubectl apply -f app-Role.yaml
role.rbac.authorization.k8s.io/app-authorization-Role created
[root@k8s-master1 app]# cat app-Role.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
namespace: app #指定命名空间
name: app-authorization-Role
rules:
- apiGroups: [ "" ] #支持的API组列表,"" 空字符串，表示核心API群
resources: [ "pod" ] #支持的资源对象列表
verbs: [ "get","delete","create","delete","exec" ] #允许的对资源对象的操作方法列表
apiGroups表示支持的API组列表：“”,“apps”, “autoscaling”, “batch”;
resources: 支持的资源对象列表
“services”, “endpoints”, “pods”,“secrets”,“configmaps”,“crontabs”,“deployments”,“jobs”,
“nodes”,“rolebindings”,“clusterroles”,“daemonsets”,“replicasets”,“statefulsets”,
“horizontalpodautoscalers”,“replicationcontrollers”,“cronjobs”
verbs: 对资源对象的操作方法列表
“get”, “list”, “watch”, “create”, “update”, “patch”, “delete”, “exec”
RoleBinding可以将同一namespace中的subject(用户、用户组)绑定到某个Role(规则)下，则此subject即具有该Role定义的权限.
[root@k8s-master1 app]# cat app-RoleBinding.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: app-authorization-role-binding
namespace: app
subjects:
- kind: User
name: xiaom
apiGroup: rbac.authorization.k8s.io
roleRef:
kind: Role
name: app-authorization-Role
apiGroup: rbac.authorization.k8s.io
[root@k8s-master1 app]# kubectl apply -f app-RoleBinding.yaml
创建一个xiaom的集群用户验证一下
[root@k8s-master1 user]# pwd
/opt/certs/user
(umask 077;openssl genrsa -out xiaom.key 2048)
[root@k8s-master1 user]# openssl req -new -key xiaom.key -out xiaom.csr -subj "/CN=xiaom/O=xiaomgroup"
[root@k8s-master1 user]# openssl x509 -req -in xiaom.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out xiaom.crt -days 3650
[root@k8s-master1 app]# kubectl config set-cluster kubernetes --embed-certs=true --certificate-authority=/opt/kubernetes/certs/ca.pem --server=https://192.168.21.120:6443
[root@k8s-master1 app]# kubectl config set-credentials xiaom --embed-certs=true --client-certificate=/opt/certs/user/xiaom.crt --client-key=/opt/certs/user/xiaom.key
User "xiaom" set.
[root@k8s-master1 app]# kubectl config set-context xiaom@kubernetes --cluster=kubernetes --user=xiaom
Context "xiaom@kubernetes" modified.
[root@k8s-master1 app]# kubectl config use-context xiaom@kubernetes
Switched to context "xiaom@kubernetes".
[root@k8s-master1 ~]# kubectl get pods -n app
NAME READY STATUS RESTARTS AGE
dsf-67b6bd65c9-44rl4 2/2 Running 18 (17h ago) 26d
host-path-nginx 2/2 Running 2 (17h ago) 17h
ingress-nginx-controller-74974c55bd-2bw2r 1/1 Running 7 (17h ago) 2d22h
ingress-nginx-controller-74974c55bd-j24mf 1/1 Running 11 (17h ago) 32d
nginx-55c7d65db4-t6mgz 1/1 Running 0 79m
postgres-sonar-5b9d94cd6b-965tk 1/1 Running 3 (141m ago) 2d22h
tomcat-657677ffb5-2nrfc 1/1 Running 9 (17h ago) 26d
[root@k8s-master1 ~]# kubectl get deployment -n app
Error from server (Forbidden): deployments.apps is forbidden: User "xiaom" cannot list resource "deployments" in API group "apps" in the namespace "app"
咱们创建一个集群权限，将这个权限赋予给xiaom这个用户，当前xiaom这个用户没有操作deployment的权限，咱们创建一个deployment的集群权限赋予给xiaom这个用户，这样xiaom这个用户可以操作所有命名空间下的deployment
ClusterRole可以对集群范围内资源、跨namespaces的范围资源、非资源类型进行授权
[root@k8s-master1 app]# kubectl apply -f app-ClusterRole.yaml
clusterrole.rbac.authorization.k8s.io/app-authorization-clusterrole created
[root@k8s-master1 app]# cat app-ClusterRole.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: app-authorization-clusterrole
rules:
- apiGroups: [ "apps" ]
resources: [ "deployments" ]
verbs: [ "get","delete","create","delete" ]
ClusterRoleBinding在整个集群级别和所有namespaces，将不同namespace中的subject(用户、用户组)与ClusterRole(集群范围内资源)绑定，授予权限
[root@k8s-master1 app]# kubectl apply -f app-ClusterRoleBinding.yaml
clusterrolebinding.rbac.authorization.k8s.io/app-authorization-clusterrole-binding created
[root@k8s-master1 app]# cat app-ClusterRoleBinding.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: app-authorization-clusterrole-binding
subjects:
- kind: User
name: xiaom
apiGroup: rbac.authorization.k8s.io
roleRef:
kind: ClusterRole
name: app-authorization-clusterrole
apiGroup: rbac.authorization.k8s.io
RoleBinding可以引用ClusterRole，对属于同一命名空间内ClusterRole定义的资源主体进行授权
[root@k8s-master1 app]# cat app-RoleClusterBinding.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: app-ClusterRoleBinding
namespace: app
subjects:
- kind: User
name: xiaom
apiGroup: rbac.authorization.k8s.io
roleRef:
kind: ClusterRole
name: app-authorization-clusterrole
apiGroup: rbac.authorization.k8s.io
[root@k8s-master1 app]# kubectl config use-context xiaom@kubernetes
[root@k8s-master1 app]# kubectl get deployment -A
NAMESPACE NAME READY UP-TO-DATE AVAILABLE AGE
app busybox 0/0 0 0 35d
app dsf 1/1 1 1 26d
app hostpath 0/0 0 0 35d
app ingress-nginx-controller 2/2 2 2 32d
app nginx 1/1 1 1 26d
app postgres-sonar 1/1 1 1 3d
app tomcat 1/1 1 1 32d
kube-devops jenkins 1/1 1 1 2d4h
kube-devops nexus-sonatype-nexus 1/1 1 1 2d4h
kube-system calico-kube-controllers 1/1 1 1 2d23h
kube-system coredns 1/1 1 1 2d22h
kubernetes-dashboard dashboard-metrics-scraper 1/1 1 1 70d
kubernetes-dashboard kubernetes-dashboard 1/1 1 1 70d
nfs-provisioner nfs-subdir-external-provisioner 2/2 2 2 50d
test tomcat-deploy 1/1 1 1 13d
[root@k8s-master1 app]# kubectl delete deployment hostpath -n app
deployment.apps "hostpath" deleted
这样xiaom这个用户就有操作所有命名空间下的deployment的权限