Use Google Auth's load_credentials_from_* Methods

These methods handle services accounts as well any any other credential
method. Got someone using DBT with AWS-based Auth (see #86)? This will
work with AWS Auth.

Typical service account auth with a key file and oauth2 jwt assertion grant
stuff still works and is covered here: https://github.com/googleapis/google-auth-library-python/blob/v2.14.1/google/auth/_default.py#L408

I did add `google-auth>=2.20.0` which is the first version that has
`load_credentials_from_dict`. Previously this lower bound was v2.14.1
(from `google-api-core>=2.11`).

Basically this will just let folks auth bigquery however they would auth
any gcloud resources without any extra effort. And the previous versions
config still works exactly the same.

Author: chrisguitarguy

dbt/adapters/bigquery/credentials.py

@@ -4,11 +4,10 @@
 from functools import lru_cache
 from typing import Any, Dict, Iterable, Optional, Tuple, Union
 
-from google.auth import default
+from google.auth import default, load_credentials_from_file, load_credentials_from_dict
 from google.auth.exceptions import DefaultCredentialsError
 from google.auth.impersonated_credentials import Credentials as ImpersonatedCredentials
 from google.oauth2.credentials import Credentials as GoogleCredentials
-from google.oauth2.service_account import Credentials as ServiceAccountCredentials
 from mashumaro import pass_through
 
 from dbt_common.clients.system import run_cmd
@@ -197,15 +196,15 @@ def _create_google_credentials(credentials: BigQueryCredentials) -> GoogleCreden
         creds, _ = _create_bigquery_defaults(scopes=credentials.scopes)
 
     elif credentials.method == _BigQueryConnectionMethod.SERVICE_ACCOUNT:
-        creds = ServiceAccountCredentials.from_service_account_file(
+        creds, _ = load_credentials_from_file(
             credentials.keyfile, scopes=credentials.scopes
         )
 
     elif credentials.method == _BigQueryConnectionMethod.SERVICE_ACCOUNT_JSON:
         details = credentials.keyfile_json
         if _is_base64(details):  # type:ignore
             details = _base64_to_string(details)
-        creds = ServiceAccountCredentials.from_service_account_info(
+        creds, _ = load_credentials_from_dict(
             details, scopes=credentials.scopes
         )
 

pyproject.toml

@@ -31,6 +31,7 @@ dependencies = [
     "google-cloud-dataproc~=5.0",
     # ----
     # Expect compatibility with all new versions of these packages, so lower bounds only.
+    "google-auth>=2.20.0",
     "google-api-core>=2.11.0",
     # add dbt-core to ensure backwards compatibility of installation, this is not a functional dependency
     "dbt-core>=1.8.0",