google.api_core.exceptions.ServiceUnavailable: 503 Getting metadata from plugin failed with error: 'str' object has no attribute 'before_request'

I’m trying to iterate through images in a directory and get their labels through goodle_api_vision. This is my code:

def run_quickstart():
import io
import os
import cv2
import numpy as np
from google.cloud import vision
from google.cloud.vision import types

client = vision.ImageAnnotatorClient(credentials = 'service_acc_key.json')

path = 'E:\wrand\\'
for image_path in os.listdir(path):

    file_name = path + image_path
    content = cv2.imread(file_name)
    content = content.tobytes()
    print(type(content))

    image = types.Image(content=content)
    print(type(image))
    response = client.label_detection(image=image)
    labels = response.label_annotations
    print('Labels:')
    for label in labels:
        print(label.description)
    
if __name__ == '__main__':
    run_quickstart()

the error that I get is at this part of code image = types.Image(content=content). The full error being

<class 'bytes'>
<class 'google.cloud.vision_v1.types.Image'>
ERROR:root:AuthMetadataPluginCallback " 
<google.auth.transport.grpc.AuthMetadataPlugin object at 
0x0000028520DCA2E8>" raised exception!
Traceback (most recent call last):
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site- 
packages\grpc\_plugin_wrapping.py", line 77, in __call__
    callback_state, callback))
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site- 
packages\google\auth\transport\grpc.py", line 77, in __call__
    callback(self._get_authorization_headers(context), None)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site
packages\google\auth\transport\grpc.py", line 61, in 
_get_authorization_headers
    self._credentials.before_request(
AttributeError: 'str' object has no attribute 'before_request'
Traceback (most recent call last):
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site- 
packages\google\api_core\grpc_helpers.py", line 54, in error_remapped_callable
return callable_(*args, **kwargs)
File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\grpc\_channel.py", line 487, in __call__
return _end_unary_response_blocking(state, call, False, deadline)
File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\grpc\_channel.py", line 437, in _end_unary_response_blocking
raise _Rendezvous(state, None, None, deadline)
grpc._channel._Rendezvous: <_Rendezvous of RPC that terminated with (StatusCode.UNAVAILABLE, Getting metadata from plugin failed with error: 'str' object has no attribute 'before_request')>

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "Tutorial.py", line 32, in <module>
run_quickstart()
  File "Tutorial.py", line 24, in run_quickstart
response = client.label_detection(image=image)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\google\cloud\vision_helpers\decorators.py", line 117, in inner
response = self.annotate_image(request, retry=retry, timeout=timeout)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\google\cloud\vision_helpers\__init__.py", line 67, in annotate_image
r = self.batch_annotate_images([request], retry=retry, timeout=timeout)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\google\cloud\vision_v1\gapic\image_annotator_client.py", line 165, in batch_annotate_images
request, retry=retry, timeout=timeout, metadata=metadata)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\google\api_core\gapic_v1\method.py", line 139, in __call__
return wrapped_func(*args, **kwargs)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\google\api_core\grpc_helpers.py", line 56, in error_remapped_callable
six.raise_from(exceptions.from_grpc_error(exc), exc)
  File "<string>", line 3, in raise_from
google.api_core.exceptions.ServiceUnavailable: 503 Getting metadata from plugin failed with error: 'str' object has no attribute 'before_request'

I put the line content = content.tobytes() because otherwise I get this error has type <class 'numpy.ndarray'>, but expected one of: ((<class 'bytes'>,),) (always at this method call image = types.Image(content=content))

[theacodes]

@stefano9-4 unfortunately you can’t just pass a string directly as the credentials argument (although perhaps we should make it where you can), you should do this instead:

from google.oauth2 import service_account

credentials = service_account.Credentials. from_service_account_file('service_acc_key.json')

client = vision.ImageAnnotatorClient(credentials=credentials)

[tseaver]

@thyatt67 Your issue is different than this one: it is really the same as #7381: you are creating once client instance per image, which is causing you to be rate-limited on the authentication service. As I suggested on that issue, create a single Client instance at the top-level of your script, and pass it through to your detect_safe_search_uri function.