K
Q

How can I allow port-forwarding for a specific deployment in Kubernetes?

6/19/2019

I am trying to allow some users in my org to forward ports to our production namespace in Kubernetes. However, I don't want them to be able to forward ports to all services. I want to restrict access to only certain services. Is this possible?

kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: allow-port-forward-for-deployment-a
rules:
- apiGroups: [""]
  resources: ["pods/portforward"]
  verbs: ["get", "list", "create"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: allow-port-forward-for-deployment-a
  namespace: production
subjects:
- kind: User
  name: "xyz@org.com"
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: ClusterRole
  name: allow-port-forward-for-deployment-a
  apiGroup: rbac.authorization.k8s.io

The above set up allows all services, but I don't want that.

-- VBoi
kubernetes
rbac
user-roles

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2 Answers

6/20/2019

Assuming users already have access to your kubernetes cluster and relevant namespace. They can simply port-forward local port to a pod (resource) port.

How can you do this? kubectl port-forward <POD_NAME> <LOCAL_PORT>:<POD_PORT>

See Documentation

Quoting from the document - kubectl port-forward allows using resource name, such as a pod name, to select a matching pod to port forward to since Kubernetes v1.10.

Refer this article if you wish, this nicely explains when you would need RBAC vs kubectl port-forward RBAC could have been useful only when, you wanted person or a group of people only to port-forward for any services in a relevant namespace in your kubernetes cluster.

-- sulabh chaturvedi
Source: StackOverflow
6/19/2019

I believe you can't. According to the docs

Resources can also be referred to by name for certain requests through the resourceNames list. When specified, requests can be restricted to individual instances of a resource. To restrict a subject to only “get” and “update” a single configmap, you would write:

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: default
  name: configmap-updater
rules:
- apiGroups: [""]
  resources: ["configmaps"]
  resourceNames: ["my-configmap"]
  verbs: ["update", "get"]

Note that create requests cannot be restricted by resourceName, as the object name is not known at authorization time. The other exception is deletecollection.

Since you want to give the user permissions to create the forward ports, I don't think you can.

-- Jose Armesto
Source: StackOverflow