kubernetes系统:发现角色机制

Question

我想了解一下system:discovery角色在kubernetes中是如何工作的，我可以看到下面的非资源url是system:discovery角色中包含的权限。

root@kubemas:~# kubectl describe clusterrole system:discovery
Name:         system:discovery
Labels:       kubernetes.io/bootstrapping=rbac-defaults
Annotations:  rbac.authorization.kubernetes.io/autoupdate: true
PolicyRule:
  Resources  Non-Resource URLs  Resource Names  Verbs
  ---------  -----------------  --------------  -----
             [/api/*]           []              [get]
             [/api]             []              [get]
             [/apis/*]          []              [get]
             [/apis]            []              [get]
             [/healthz]         []              [get]
             [/livez]           []              [get]
             [/openapi/*]       []              [get]
             [/openapi]         []              [get]
             [/readyz]          []              [get]
             [/version/]        []              [get]
             [/version]         []              [get]

从clusterrolebinding描述中。

root@kubemas:~# kubectl describe clusterrolebindings.rbac.authorization.k8s.io system:discovery
Name:         system:discovery
Labels:       kubernetes.io/bootstrapping=rbac-defaults
Annotations:  rbac.authorization.kubernetes.io/autoupdate: true
Role:
  Kind:  ClusterRole
  Name:  system:discovery
Subjects:
  Kind   Name                  Namespace
  ----   ----                  ---------
  Group  system:authenticated  

我可以看到只有system:authenticated组才能访问非资源url.如果我执行下面的命令，我可以理解，请求用户是system:anonymous，它隶属于system:unathenticated组，所以不允许看到输出。

root@kubemas:~# curl -k https://192.168.56.101:6443/api
{
  "kind": "Status",
  "apiVersion": "v1",
  "metadata": {

  },
  "status": "Failure",
  "message": "forbidden: User \"system:anonymous\" cannot get path \"/api\"",
  "reason": "Forbidden",
  "details": {

  },
  "code": 403

但我希望从下面的请求中得到同样的结果，我试图得到kubernetes的版本，这也是非资源url.但我可以无误地得到版本输出，所以这是如何工作的，我是否误解了这个机制？

root@kubemas:~# curl -k https://192.168.56.101:6443/version
{
  "major": "1",
  "minor": "18",
  "gitVersion": "v1.18.3",
  "gitCommit": "2e7996e3e2712684bc73f0dec0200d64eec7fe40",
  "gitTreeState": "clean",
  "buildDate": "2020-05-20T12:43:34Z",
  "goVersion": "go1.13.9",
  "compiler": "gc",
  "platform": "linux/amd64"
}root@kubemas:~#

Answer 1

system:public-info-viewer 是提供访问权限的集群角色 /version. 这个簇状ole必然是 system:authenticated 和 system:unauthenticated 组。由于它必然会 system:unauthenticated 组，您就可以访问它。

从 文件

该集群ole 允许只读访问集群的非敏感信息。在Kubernetes v1.14中引入。

kubectl describe clusterrole system:public-info-viewer
Name:         system:public-info-viewer
Labels:       kubernetes.io/bootstrapping=rbac-defaults
Annotations:  rbac.authorization.kubernetes.io/autoupdate: true
PolicyRule:
  Resources  Non-Resource URLs  Resource Names  Verbs
  ---------  -----------------  --------------  -----
             [/healthz]         []              [get]
             [/livez]           []              [get]
             [/readyz]          []              [get]
             [/version/]        []              [get]
             [/version]         []              [get]