fetch_service_config.py 文件源码

def fetch_access_token(metadata):
    """Fetch access token from metadata URL."""
    access_token_url = metadata + _METADATA_PATH + "/service-accounts/default/token"
    headers = {"Metadata-Flavor": "Google"}
    client = urllib3.PoolManager(ca_certs=certifi.where())
    try:
        response = client.request("GET", access_token_url, headers=headers)
    except:
        raise FetchError(1,
            "Failed to fetch access token from the metadata server: " + access_token_url)
    status_code = response.status

    if status_code != 200:
        message_template = "Fetching access token failed (url {}, status code {})"
        raise FetchError(1, message_template.format(access_token_url, status_code))

    token = json.loads(response.data)["access_token"]
    return token