helper.py

"""
Running this python script helps you to find the SUPABASE_JWT_PUBLIC_KEY environment to be placed in the .env file

To run this file type in the following terminal command when you are in the root level.
python helper.py

Ensure that the dependencies below such as cryptography are listed in the requirements.txt.
Install them by running this command.
pip install -r requirements.txt
"""


import json
import os
from pathlib import Path
from urllib.request import urlopen

from dotenv import load_dotenv
from cryptography.hazmat.primitives import serialization
from jwt.algorithms import ECAlgorithm

load_dotenv(dotenv_path=Path(__file__).resolve().parent / ".env")

supabase_url = os.environ.get("SUPABASE_URL")
if not supabase_url:
  raise ValueError("SUPABASE_URL environment variable is not set.")

jwks_url = f"{supabase_url.rstrip('/')}/auth/v1/.well-known/jwks.json"
with urlopen(jwks_url) as response:
  jwks = json.loads(response.read().decode("utf-8"))

keys = jwks.get("keys", [])
if not keys:
  raise ValueError(f"No JWK keys returned from {jwks_url}")

public_key = None
last_error = None
for jwk in keys:
  try:
    public_key = ECAlgorithm.from_jwk(json.dumps(jwk))
    break
  except Exception as exc:
    last_error = exc

if public_key is None:
  raise ValueError(f"Unable to parse any JWKS key from {jwks_url}: {last_error}")

pem = public_key.public_bytes(
  encoding=serialization.Encoding.PEM,
  format=serialization.PublicFormat.SubjectPublicKeyInfo,
).decode("utf-8")

print(pem)