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Kubernetes RBAC

In KubeVela v1.4, Authentication & Authorization mechanism is introduced. This allows applications to dispatch and manage resources using the identity of the application's creator/modifier. With this feature, it will be easy to limit the access of KubeVela users/applications and isolate their living spaces, which will make your KubeVela system safer.

Installation

To enable Authentication & Authorization in your KubeVela system, you need to do the following steps

  1. Delete the ClusterRoleBinding ends with vela-core:manager-rolebinding. Usually you can do it through:

    kubectl delete ClusterRoleBinding kubevela-vela-core:manager-rolebinding
  2. Upgrade the controller, and wait for the installation finished:

    helm upgrade --install kubevela kubevela/vela-core --create-namespace -n vela-system --set authentication.enabled=true --set authentication.withUser=true --wait
  3. Make sure your version Vela CLI v1.4.1+, refer to the installation guide.

  4. (Optional) Install vela-prism through running the following commands, which will allow you to enjoy the advanced API extensions in KubeVela.

    helm repo add prism https://charts.kubevela.net/prism
    helm repo update
    helm install vela-prism prism/vela-prism -n vela-system

Usage

  1. Before we start, assume we already have two managed clusters joined in KubeVela, called c2 and c3. You can refer to the multi-cluster document and see how to join managed clusters into KubeVela control plane.
$ vela cluster list
NAME ALIAS CREDENTIAL_TYPE ENDPOINT ACCEPTED LABELS
local Internal - true
c3 X509Certificate <c3 apiserver url> true
c2 X509Certificate <c2 apiserver url> true

Create User

  1. Let's start with a new coming user named Alice. As the system administrator, you can assign a KubeConfig for Alice to use.
$ vela auth gen-kubeconfig --user alice > alice.kubeconfig
Private key generated.
Certificate request generated.
Certificate signing request alice generated.
Certificate signing request alice approved.
Signed certificate retrieved.

Grant Privileges

  1. Now alice is unabled to do anything in the cluster with the given KubeConfig. We can grant her the privileges of Read/Write resources in the dev namespace of the control plane and managed cluster c2.
$ vela auth grant-privileges --user alice --for-namespace dev --for-cluster=c2 --create-namespace
ClusterRole kubevela:writer created in c2.
RoleBinding dev/kubevela:writer:binding created in c2.
Privileges granted.
  1. We can check the privileges of Alice by the following command
$ vela auth list-privileges --user alice --cluster local,c2
User=alice
├── [Cluster] local
│ └── no privilege found
└── [Cluster] c2
└── [ClusterRole] kubevela:writer
├── [Scope]
│ └── [Namespaced] dev (RoleBinding kubevela:writer:binding)
└── [PolicyRules]
├── APIGroups: *
│ Resources: *
│ Verb: get, list, watch, create, update, patch, delete
└── NonResourceURLs: *
Verb: get, list, watch, create, update, patch, delete

Alice don't have any privilege in local cluster while she have read/write capability in namespace(dev) of cluster(c2).

Use Privileges

  1. Alice can create an application in the dev namespace now. The application can also dispatch resources into the dev namespace of cluster c2.
cat <<EOF | KUBECONFIG=alice.kubeconfig vela up -f -
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: podinfo
namespace: dev
spec:
components:
- name: podinfo
type: webservice
properties:
image: stefanprodan/podinfo:6.0.1
policies:
- type: topology
name: topology
properties:
clusters: ["c2"]
EOF
  1. Alice can see the the application is successfully deployed.
$ KUBECONFIG=alice.kubeconfig vela status podinfo -n dev
About:

Name: podinfo
Namespace: dev
Created at: 2022-05-31 17:06:14 +0800 CST
Status: running

Workflow:

mode: DAG
finished: true
Suspend: false
Terminated: false
Steps
- id:rk3npcpycl
name:deploy-topology
type:deploy
phase:succeeded
message:

Services:

- Name: podinfo
Cluster: c2 Namespace: dev
Type: webservice
Healthy Ready:1/1
No trait applied

Unauthorized access forbidden

  1. If Alice wants to access resources outside the dev namespace, she will be forbidden to do so.
KUBECONFIG=alice.kubeconfig kubectl get pod -n vela-system
Error from server (Forbidden): pods is forbidden: User "alice" cannot list resource "pods" in API group "" in the namespace "vela-system"
  1. If Alice try to create a application in the dev namespace and the application intends to dispatch resources in c3 cluster (which Alice does not have the privileges), the application will not be able to do so.

Alice create the application podinfo-bad

$ cat <<EOF | KUBECONFIG=alice.kubeconfig vela up -f -
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: podinfo-bad
namespace: dev
spec:
components:
- name: podinfo-bad
type: webservice
properties:
image: stefanprodan/podinfo:6.0.1
policies:
- type: topology
name: topology
properties:
clusters: ["c3"]
EOF

Alice checks the status of podinfo-bad, the error message will be shown.

$ KUBECONFIG=alice.kubeconfig vela status podinfo-bad -n dev
About:

Name: podinfo-bad
Namespace: dev
Created at: 2022-05-31 17:09:16 +0800 CST
Status: runningWorkflow

Workflow:

mode: DAG
finished: false
Suspend: false
Terminated: false
Steps
- id:tw539smx7m
name:deploy-topology
type:deploy
phase:failed
message:step deploy: run step(provider=multicluster,do=deploy): Found 1 errors. [(error encountered in cluster c3: HandleComponentsRevision: controllerrevisions.apps is forbidden: User "alice" cannot list resource "controllerrevisions" in API group "apps" in the namespace "dev")]

Services:

Readonly Access

  1. Let's create a new KubeConfig for another new User Bob. Bob will only be granted with the readonly privileges for the resources in the dev namespace of the control plane and cluster c2.
$ vela auth gen-kubeconfig --user bob > bob.kubeconfig
Private key generated.
Certificate request generated.
Certificate signing request bob generated.
Certificate signing request bob approved.
Signed certificate retrieved.

$ vela auth grant-privileges --user bob --for-namespace dev --for-cluster=local,c2 --readonly
ClusterRole kubevela:reader created in local.
RoleBinding dev/kubevela:reader:binding created in local.
ClusterRole kubevela:reader created in c2.
RoleBinding dev/kubevela:reader:binding created in c2.
Privileges granted.
  1. User Bob can see the applications and their status under the namespace of dev.
$ KUBECONFIG=bob.kubeconfig vela ls -n dev
APP COMPONENT TYPE TRAITS PHASE HEALTHY STATUS CREATED-TIME
podinfo podinfo webservice running healthy Ready:1/1 2022-05-31 17:06:14 +0800 CST
podinfo-bad podinfo-bad webservice workflowTerminated 2022-05-31 17:09:16 +0800 CST

$ KUBECONFIG=bob.kubeconfig vela status podinfo -n dev
About:

Name: podinfo
Namespace: dev
Created at: 2022-05-31 17:06:14 +0800 CST
Status: running

Workflow:

mode: DAG
finished: true
Suspend: false
Terminated: false
Steps
- id:rk3npcpycl
name:deploy-topology
type:deploy
phase:succeeded
message:

Services:

- Name: podinfo
Cluster: local Namespace: dev
Type: webservice
Healthy Ready:1/1
No trait applied

- Name: podinfo
Cluster: c2 Namespace: dev
Type: webservice
Healthy Ready:1/1
No trait applied
  1. But he is forbidden to do any mutating actions, such as deleting application in dev namespace.
$ KUBECONFIG=bob.kubeconfig vela delete podinfo-bad -n dev
Deleting Application "podinfo-bad"
Error: delete application err: applications.core.oam.dev "podinfo-bad" is forbidden: User "bob" cannot delete resource "applications" in API group "core.oam.dev" in the namespace "dev"
2022/05/31 17:17:51 delete application err: applications.core.oam.dev "podinfo-bad" is forbidden: User "bob" cannot delete resource "applications" in API group "core.oam.dev" in the namespace "dev"
  1. Instead, User Alice can delete application.
$ KUBECONFIG=alice.kubeconfig vela delete podinfo-bad -n dev
application.core.oam.dev "podinfo-bad" deleted

Listing resources in Application

  1. (Optional) After vela-prism installed, you will be able to list resources of the application through the following command
$ KUBECONFIG=bob.kubeconfig vela status podinfo -n dev --tree --detail
CLUSTER NAMESPACE RESOURCE STATUS APPLY_TIME DETAIL
c2 ─── dev ─── Deployment/podinfo updated 2022-05-31 17:06:14 Ready: 1/1 Up-to-date: 1 Available: 1 Age: 13m
local ─── dev ─── Deployment/podinfo updated 2022-05-31 17:06:14 Ready: 1/1 Up-to-date: 1 Available: 1 Age: 13m

Notice that if vela-prism is not installed, Alice and Bob will be forbidden to run this listing command.

Extension Reading

The guide above demonstrates how system operators can grant limited privileges for users and therefore restrict the access of their created applications. For more detail explanation on how this capability is achieved, read the Underlying Mechanism article.

As the platform builder, you may want to bind KubeVela application with your customized identity. For example, using a manual specified ServiceAccount for the application. If you want to do so, it is not mandatory to enable the Authentication feature flag in KubeVela. Read the System Integration for more details.