BigQuery 库中的 [AssertionCredentials] 参数是什么以及如何获取它？

Question

BigQuery-Python is a small python package that provides functions to interact with GCP's BigQuery. To use it one needs to first instantiate a client object. The documentation for the function get_client() states that

def get_client(project_id=None, credentials=None,
               service_url=None, service_account=None,
               private_key=None, private_key_file=None,
               json_key=None, json_key_file=None,
               readonly=True, swallow_results=True,
               num_retries=0):
    """Return a singleton instance of BigQueryClient. Either
    AssertionCredentials or a service account and private key combination need
    to be provided in order to authenticate requests to BigQuery.
    Parameters
    ----------
    project_id : str, optional
        The BigQuery project id, required unless json_key or json_key_file is
        provided.
    credentials : oauth2client.client.SignedJwtAssertionCredentials, optional
        AssertionCredentials instance to authenticate requests to BigQuery
        (optional, must provide `service_account` and (`private_key` or
        `private_key_file`) or (`json_key` or `json_key_file`) if not included

Can someone explain to me what is the credentials parameter is and how to use it properly?

Answer 1

The credentials parameter in the case of that library refers to means of authenticating with GCP.

The developer has provided examples in the documentation .

You must first create your service account in GCP . Then you can download a JSON key for that service account which you use in authenticating with the service. Eg

# JSON key provided by Google
json_key = 'key.json'
 
client = get_client(json_key_file=json_key, readonly=True)

It should be noted that this is a third-party library and it seems to require setting up a service account and downloading credentials but this isn't considered a best practice. You should use attached service accounts wherever possible . These will use Application Default Credentials which are better from a management and security point of view.