• Kubernetes RBAC(Role-based access control)
  • Components of RBAC:
    • Users vs Service Accounts
  • Provide Access at Namespace Level
    • Create a Service Account
    • Configure kubectl with your Service Account
    • Create a Role
    • Create a RoleBinding
    • Verify your service account has been granted the Role’s Permissions
  • Provide access at Cluster Level
    • Create ClusterRole
    • Create ClusterRoleBinding
  • Provide Access to KeyCloak and Ingress Namespaces

Kubernetes RBAC(Role-based access control)

Kubernetes RBAC is a way to regulating access to Kubernetes Resources. It enables you to Provide fine-grained control over who can access and perform actions within a Kubernetes cluster. With RBAC, administrators can grant different levels of access to users or groups based on their roles, ensuring that only authorized entities can perform specific actions.

Components of RBAC:

1. Roles: A Role always sets permissions within a particular namespace; when you create a Role, you have to specify the namespace it belongs in.
2. RoleBindings: A role binding grants the permissions defined in a role to a user or set of users. It holds a list of subjects (users, groups, or service accounts), and a reference to the role being granted.
3. ClusterRoles: ClusterRole, by contrast, is a non-namespaced resource. The resources have different names (Role and ClusterRole)
4. ClusterRoleBindings: you want to bind a ClusterRole to all the namespaces in your cluster, you use a ClusterRoleBinding

Users vs Service Accounts

1. Users: In Kubernetes, a User represents a human who authenticates to the cluster using an external service.
2. Service Accounts: Service Accounts are token values that can be used to grant access to namespaces in your cluster. They’re designed for use by applications and system components.

Provide Access at Namespace Level

Make sure your kubernetes context set to right to access the cluster

kubectl config current-context
default

If the context is not set to right please update the context using

kubectl config use-context $CONTEXT_NAME

Create a Service Account

kubectl create serviceaccount demo-user
serviceaccount/demo-user created

Next, run the following command to create an authorization token for your Service Account:

$ TOKEN=$(kubectl create token demo-user)

Configure kubectl with your Service Account

Now add a new kubectl context that lets you authenticate as your Service Account. First, add your Service Account as a credential in your Kubeconfig file:

kubectl config set-credentials demo-user --token=$TOKEN
User "demo-user" set.

Next, add your new context—we’re calling it demo-user-context.

kubectl config set-context demo-user-context --cluster=default --user=demo-user

Use the context that is just created

kubectl config use-context demo-user-context
Switched to context "demo-user-context".

to validate the context

kubectl config current-context
demo-user-context

Try to list the Pods in the namespace:

$ kubectl get pods

Error from server (Forbidden): pods is forbidden: User "system:serviceaccount:default:demo-user" cannot list resource "pods" in API group "" in the namespace "default"

This service account does not have permissions to list the pods in default namespace

Create a Role

witch back to the Kubectl context that authenticates as Admin User:

kubectl config use-context $CONTEXT_NAME

A Role (or ClusterRole) object is required for each of the roles you want to use with Kubernetes.

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: demo-role
  namespace: default
rules:
  - apiGroups:
      - ""
    resources:
      - pods
    verbs:
      - get
      - list
      - create
      - update

Save the Role manifest to role.yaml, then use Kubectl to add it to your cluster:

kubectl apply -f role.yaml
role.rbac.authorization.k8s.io/demo-role created

Create a RoleBinding

The Role has been created but it’s not yet assigned to your Service Account. A RoleBinding is required to make this connection.

apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: demo-role-binding
  namespace: default
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: demo-role
subjects:
  - namespace: default
    kind: ServiceAccount
    name: demo-user

Save the RoleBinding manifest as rolebinding.yaml, then add it to your cluster to grant your role to your user:

$ kubectl apply -f rolebinding.yaml
rolebinding.rbac.authorization.k8s.io/demo-role-binding created

Verify your service account has been granted the Role’s Permissions

witch back to the Kubectl context that authenticates as the Service Account user:

$ kubectl config use-context demo-user-context
Switched to context "demo-user-context".

Verify that the get pods command now runs successfully:

kubectl get pods
No resources found in default namespace.

You can also try creating a Pod as your Service Account as Role have the permissions on resources types pods

$ kubectl run nginx --image=nginx:latest
pod/nginx created

The Pod is successfully created:

$ kubectl get pods
NAME    READY   STATUS    RESTARTS   AGE
nginx   1/1     Running   0          15s

However, it’s not possible for the Service Account user to delete Pods because the Role you’ve assigned doesn’t include the required delete action verb:

$ kubectl delete pod nginx
Error from server (Forbidden): pods "nginx" is forbidden: User "system:serviceaccount:default:demo-user" cannot delete resource "pods" in API group "" in the namespace "default"

These Permissions at Namespace level. In this example it is at default namespace.

Provide access at Cluster Level

If we want ot provide Same permissions at Cluster Level

Create ClusterRole

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: demo-role
rules:
  - apiGroups:
      - ""
    resources:
      - pods
    verbs:
      - get
      - list
      - create
      - update

Save the Role manifest to cluster-role.yaml, then use Kubectl to add it to your cluster:

kubectl apply -f cluster-role.yaml

Create ClusterRoleBinding

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: demo-role-binding
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: demo-role
subjects:
  - namespace: default
    kind: ServiceAccount
    name: demo-user

Save the RoleBinding manifest as clusterrolebinding.yaml, then add it to your cluster to grant your role to your user:

$ kubectl apply -f clusterrolebinding.yaml
rolebinding.rbac.authorization.k8s.io/demo-role-binding created

Now you able to list pods in All Namespaces

kubectl get pods -A

Kubernetes provides default ClusterRoles such as cluster-admin, view, and edit. The cluster-admin role grants full access to perform any action on any resource within the cluster. Other default roles like view provide read-only access to cluster resources, and edit allows users to create, update, and delete resources, but not access sensitive information like secrets.

Provide Access to KeyCloak and Ingress Namespaces

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: access-logs
rules:
  - apiGroups: ["apps"]
    resources: ["deployments"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["services"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["ingresses"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["pods", "pods/log"]
    verbs: ["get", "list", "watch", "logs"]
  - apiGroups: [""]
    resources: ["secrets"]
    verbs: ["*"]
    resourceNames: [""] # Deny access to all secrets
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: keycloak-namespace-access-binding
  namespace: keycloak
subjects:
  - kind: ServiceAccount
    name: $SERVICE_ACCOUNT_NAME
    namespace: keycloak
roleRef:
  kind: ClusterRole
  name: access-logs
  apiGroup: rbac.authorization.k8s.io
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: ingress-namespace-access-binding
  namespace: ingress-nginx
subjects:
  - kind: ServiceAccount
    name: $SERVICE_ACCOUNT_NAME
    namespace: ingress-nginx
roleRef:
  kind: ClusterRole
  name: access-logs
  apiGroup: rbac.authorization.k8s.io

Save the Role manifest to access-log.yaml, then use Kubectl to add it to your cluster:

kubectl apply -f access-log.yaml