Kubernetes User Creator

The goal of this project is to make it easy to create a Kubernetes user. While the k8s documentation is quick to point out that users do not exist in Kubernetes, sometimes you just want to generate a kubeconfig which has access to the cluster.

This access can be achived by the following means:

• create a Service Account with a token with access to the cluster
• create a RSA certificate/key pair allowing access to the cluster

The "user" is not given any permissions be default, so you still need to create/associate the user with ClusterRoleBindings/RoleBindgins.

This project is inspired by the following blog post: https://www.openlogic.com/blog/granting-user-access-your-kubernetes-cluster

TODO

• Automate the creation of openssl key and csr
• Automate the creation of a k8s CSR resource
• Automate the approval of the CSR resource
• Automate the creation of a kubeconfig
• Automate or document the creation of cluster premissions
• Create a command line tool as well as python api
• Automate the SA Token workflow
• Allow passing in SA and CSR resource metadata to CLI
• Document well
• Automate the build
• 95% test coverage

Install

pip install kubernetes-user

CLI Quick Start

Generate a CSR-based User

# basic usage

k8s_user csr myusername

# or providing a non-default kubeconfig

python -m k8s_user csr myusername \
    --kubeconfig ~/.kube/config

# or using local Git checkout

pip install -e .
python -m k8s_user csr myusername

Generate a SA-based User with token

# basic usage

k8s_user sa myusername

# or providing a non-default kubeconfig

k8s_user sa myusername \
    --kubeconfig ~/.kube/config

# or without installing

python -m k8s_user sa myusername

# or without installing and providing a non-default kubeconfig

python -m k8s_user sa myusername \
    --kubeconfig ~/.kube/config

Add a clusterrollbinding for the new user

kubectl create clusterrolebinding joe-admin --clusterrole=admin --user=joe

Python API Quick Start

Create and sign the user

import kubernetes
from kubernetes import client, config
api_client = config.new_client_from_config()

from k8s_user import CSRK8sUser
user = CSRK8sUser(name="joe")
inputs = {
    "cluster_name": "default",
    "context_name": "default",
    "out_kubeconfig": "new-kubeconfig.yaml",
    "creds_dir": ".",
}
user.create(api_client, inputs)

Add a clusterrollbinding for the new user

kubectl create clusterrolebinding joe-admin --clusterrole=admin --user=joe

Low-Level CSR API Interaction

This example assumes you are connected to a Kubernetes cluster with a kubeconfig in the default location.

import kubernetes
from kubernetes import client, config
from k8s_user.k8s.csr_resource import CSRResource
from k8s_user.pki import CSRandKey, Cert

csr_name = 'joe'

# create a KEY and CSR
candk = CSRandKey(csr_name, additional_subject={"O": "jazstudios"})

# save the csr and key
candk.csr.save("joe.csr.pem")
candk.key.save("joe.key.pem")

# create the k8s api client. Load the kubeconfig from the default location (~/.kube/config)
api_client = config.new_client_from_config()

# Define the CertificateSigningRequest Kubernetes Resource
csr = CSRResource(
    name=csr_name,  # the name of the CertificateSigningRequest k8s object
    csr_str=candk.csr.base64,  # the base64 encoded csr string
    metadata={"labels": {"foo": "bar"}},  # optional dict with fields matching k8s V1ObjectMeta object
)

# Check if the k8s CSR resource exists
csr.resource_exists(api_client)

# Create the k8s CSR resource
obj = csr.create(api_client)

# Check again if the k8s CSR resource exists (it will now)
csr.resource_exists(api_client)

# Approve the k8s CSR resource
approved_csr_obj = csr.approve(api_client)

# Get the certificate as a base64 encoded PEM string
crt_str = csr.get_cert(api_client)

# Save the certificate to a file
candk = Cert(crt_data=base64.b64decode(crt_str))
candk.save('joe.crt.pem')

Development

It is recommended that you have Docker installed in order to use the development tools for this project. The Makefile will use Docker to run the installation and unit tests.

Makefile Usage

Build a Docker image with all the deps needed to test this project.

make build

Run the unit tests for this project.

make test

Enter into an interactive shell inside a Docker, with all dependencies installed.

make shell

Clean up all temporary files generated by this project

make clean

Create a Python wheel in the dist/ directory

make package