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#!/usr/bin/env python3
import argparse
import base64
import shutil
import subprocess
import tempfile
from pathlib import Path
parser = argparse.ArgumentParser()
parser.add_argument("user", help="The name to give the created user")
parser.add_argument("--role_binding", help="The role binding to add this user to", default="devops-reader")
args = parser.parse_args()
user = args.user
role_binding = args.role_binding
CERT_REQUEST_TEMPLATE = """apiVersion: certificates.k8s.io/v1
kind: CertificateSigningRequest
metadata:
name: {user}
spec:
groups:
- system:authenticated
request: {req}
signerName: kubernetes.io/kube-apiserver-client
usages:
- client auth
"""
ROLE_BINDING_PATCH_TEMPLATE = """[
{{
"op": "add",
"path": "/subjects/0",
"value": {{
"kind": "User",
"name": "{user}"
}}
}}
]
"""
def run_and_return_output(command: str, cwd: str | None = None) -> str:
"""Run a command in a shell and return the result as a string."""
return subprocess.run( # noqa: S602
command,
shell=True,
stdout=subprocess.PIPE,
text=True,
check=True,
cwd=cwd,
).stdout
def create_cert_signing_request(tmpdir: str) -> str:
"""Create and return a CertificateSigningRequest."""
run_and_return_output("openssl genrsa -out priv.key 2048", tmpdir)
cert_req = run_and_return_output(
f"openssl req -new -key priv.key -subj /C=GB/ST=GB/O=pydis/CN={user}",
tmpdir,
)
return base64.b64encode(cert_req.encode("utf-8")).decode("utf-8").replace("\n", "")
def approve_cert_signing_request(csr: str, tmpdir: str) -> None:
"""Approve the csr and save as a file in tmpdir."""
csr_path = Path(tmpdir, "csr.yml")
with csr_path.open("w") as f:
f.write(CERT_REQUEST_TEMPLATE.format(user=user, req=csr))
run_and_return_output(f"kubectl apply -f {csr_path}", tmpdir)
run_and_return_output(f"kubectl certificate approve {user}")
approved_cert = run_and_return_output(f"kubectl get csr {user} -o jsonpath='{{.status.certificate}}'")
with Path(tmpdir, f"{user}.crt").open("w", encoding="locale") as f:
f.write(base64.b64decode(approved_cert).decode("utf-8"))
run_and_return_output(f"kubectl delete csr {user}")
def give_user_perms(tmpdir: str) -> None:
"""Add the user from args to the cluster role binding from the args."""
role_binding_patch_path = Path(tmpdir, "binding_patch.json")
with role_binding_patch_path.open("w") as f:
f.write(ROLE_BINDING_PATCH_TEMPLATE.format(user=user))
run_and_return_output(
f"kubectl patch clusterrolebinding {role_binding} --type=json --patch-file {role_binding_patch_path}",
tmpdir,
)
def build_kubectl_config(tmpdir: str) -> None:
"""Build up a kubectl config from all the files in the tmpdir."""
cluster_public_key = run_and_return_output(r"kubectl get cm kube-root-ca.crt -o jsonpath={.data.ca\.crt}")
with Path(tmpdir, "ca.crt").open("w", encoding="locale") as f:
f.write(cluster_public_key)
cluster_url = run_and_return_output("kubectl config view --minify --output jsonpath={.clusters[*].cluster.server}")
run_and_return_output(
f"kubectl config set-cluster pydis --kubeconfig={user}.config "
f"--server={cluster_url} --certificate-authority=ca.crt --embed-certs=true",
tmpdir,
)
run_and_return_output(
f"kubectl config set-credentials {user} "
f"--client-key=priv.key --client-certificate={user}.crt "
f"--embed-certs=true --kubeconfig={user}.config",
tmpdir,
)
run_and_return_output(
f"kubectl config set-context pydis --kubeconfig={user}.config "
f"--cluster=pydis --user={user} --namespace=default",
tmpdir,
)
run_and_return_output(f"kubectl config use-context pydis --kubeconfig={user}.config", tmpdir)
with tempfile.TemporaryDirectory() as tmpdir:
csr = create_cert_signing_request(tmpdir)
approve_cert_signing_request(csr, tmpdir)
give_user_perms(tmpdir)
build_kubectl_config(tmpdir)
# Move the kubectl config from tmpdir to the current working dir ready to be sent to user.
shutil.copy(
Path(tmpdir, f"{user}.config"), # from
Path(f"{user}.config"), # to
)
print(f"Config generated. Saved to {user}.config in current directory.") # noqa: T201
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