kube-role-gen

README

kube-role-gen

Create a complete Kubernetes RBAC role

kube-role-gen is a command-line utility that will generate a Kubernetes ClusterRole that contains every resource available on a connected cluster, including sub-resources & custom resources. Each entry in the ClusterRole rules are grouped by API group and the combination of unique resource type & supported verbs. This is different from something like kubectl create role ... -o yaml --dry-run=client, which groups resources together even if they all don't support the same verb (ie. pods/exec listed with the patch verb).

Why create this?

• In secure environments, even cluster admins shouldn't have access to everything. Access to resources such as namespace creation/delete, rolebindings, etc. should be reserved for cluster management tools, pipelines or scripts.
• Kubernetes will likely never support role aggregation via subtraction.
• Sub-resources such as pods/exec are not accessible via any normal kubectl output (with the only exception being kubectl --raw). It must be queried using Kubernetes API discovery via a client.
• I didn't want to maintain the original bash script to do the same thing. Props to Vit on stackoverflow for providing the idea for this utility.
• It's my own excuse to learn Go for something I need at work.

Alternatives:

• Use privileged access management for any elevated permissions inside Kubernetes.
• Use a tool such as audit2rbac to generate a least-privilege role based on what your cluster users are actually deploying

Install

Download the latest release:

curl -LO https://github.com/jitterylayo/kube-role-gen/releases/latest/download/kube-role-gen_Linux_x86_64.tar.gz
tar xf kube-role-gen_Linux_x86_64.tar.gz
mv kube-role-gen /usr/local/bin/

You can also install as a Go module.

go install github.com/jitterylayo/kube-role-gen/cmd/kube-role-gen@latest

Usage

$ kube-role-gen -h
Usage of kube-role-gen:
  -json
        Generate JSON output. If unset, will default to YAML.
  -kubeconfig string
        absolute path to the kubeconfig file. If set, this will override the default behavior and ignore KUBECONFIG environment variable and/or $HOME/.kube/config file location.
  -name string
        Override the name of the ClusterRole resource that is generated (default "foo-clusterrole")
  -pretty
        Enable human-readable JSON output. This flag is ignored for YAML (always pretty-prints).
  -v    Enable verbose logging.

The resulting ClusterRole resource will be printed to stdout in YAML format.

$ kube-role-gen
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  creationTimestamp: null
  name: foo-clusterrole
rules:
- apiGroups:
  - ""
  resources:
  - bindings
  - pods/binding
  - pods/eviction
  - serviceaccounts/token
  verbs:
  - create
- apiGroups:
  - ""
  resources:
  - componentstatuses
  verbs:
  - get
  - list
- apiGroups:
  - ""
  resources:
  - configmaps
  - endpoints
  - events
  - limitranges
  - nodes
  - persistentvolumeclaims
  - persistentvolumes
  - pods
  - podtemplates
  - replicationcontrollers
  - resourcequotas
  - secrets
  - serviceaccounts
  verbs:
  - create
  - delete
  - deletecollection
  - get
  - list
  - patch
  - update
  - watch
...

You can also redirect the output to a file and create your new roles from the generated manifest as a starting point:

$ kube-role-gen > foo-clusterrole.yaml

$ kubeval foo-clusterrole.yaml
PASS - foo-clusterrole.yaml contains a valid ClusterRole

$ kubectl apply -f foo-clusterrole.yaml
clusterrole.rbac.authorization.k8s.io/foo-clusterrole created

Manipulation / Post-Processing

This utility doesn't provide any post-processing out of the box. However, you can use tools such as jq to chain the output of kube-role-gen and manipulate it as you see fit.

Here's a few common "recipes" for manipulating the role that is generated:

No delete access

kube-role-gen -json | jq 'del(.rules[].verbs[] |           
select((. == "delete") or (. == "deletecollection")))'

Read-only access to all resources

kube-role-gen -json | jq 'del(.rules[].verbs[] |           
select((. == "create") or (. == "delete") or (. == "deletecollection") or (. == "patch") or (. == "update")))'

Exclude a specific API group

kube-role-gen -json | jq 'del(.rules[] | select(.apiGroups[] | contains("flowcontrol.apiserver.k8s.io")))' 

Exclude multiple API groups

kube-role-gen -json | jq 'del(.rules[] | select(.apiGroups[] | contains("scheduling.k8s.io") or contains("flowcontrol.apiserver.k8s.io") or contains("node.k8s.io")))'