Cloud Functions で環境変数を使う ref: https://qiita.com/flatfisher/items/e10a8e3f5dad2b2b4e71

.env.yaml

PROJECT: hogehoge
KEY: fugafuga

file0.txt

$ gcloud beta functions NAME --set-env-vars PROJECT=hogehoge KEY=fugafuga

index.js

exports.envVar = (req, res) => {
  // Sends 'bar' as response
  res.send(process.env.PROJECT);
};

main.py

def env_vars(request):
    return os.environ.get('KEY', 'Specified environment variable is not set.')