Flask web app on Cloud Run - google.auth.exceptions.DefaultCredentialsError: - python

I'm hosting a Flask web app on Cloud Run. I'm also using Secret Manager to store Service Account keys. (I previously downloaded a JSON file with the keys)
In my code, I'm accessing the payload then using os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = payload to authenticate. When I deploy the app and try to visit the page, I get an Internal Service Error. Reviewing the logs, I see:
File "/usr/local/lib/python3.10/site-packages/google/auth/_default.py", line 121, in load_credentials_from_file
raise exceptions.DefaultCredentialsError(
google.auth.exceptions.DefaultCredentialsError: File {"
I can access the secret through gcloud just fine with: gcloud secrets versions access 1 --secret="<secret_id>" while acting as the Service Account.
Here is my Python code:
# Grabbing keys from Secret Manager
def access_secret_version():
# Create the Secret Manager client.
client = secretmanager.SecretManagerServiceClient()
# Build the resource name of the secret version.
name = "projects/{project_id}/secrets/{secret_id}/versions/1"
# Access the secret version.
response = client.access_secret_version(request={"name": name})
payload = response.payload.data.decode("UTF-8")
return payload
#app.route('/page/page_two')
def some_random_func():
# New way
payload = access_secret_version() # <---- calling the payload
os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = payload
# Old way
os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = "service-account-keys.json"
I'm not technically accessing a JSON file like I was before. The payload variable is storing entire key. Is this why it's not working?

Your approach is incorrect.
When you run on a Google compute service like Cloud Run, the code runs under the identity of the compute service.
In this case, by default, Cloud Run uses the Compute Engine default service account but, it's good practice to create a Service Account for your service and specify it when you deploy it to Cloud Run (see Service accounts).
This mechanism is one of the "legs" of Application Default Credentials when your code is running on Google Cloud, you don't specify the environment variable (you also don't need to create a key) and Cloud Run service acquires the credentials from the Metadata service:
import google.auth
credentials, project_id = google.auth.default()
See google.auth package
It is bad practice to define|set an environment variable within code. By their nature, environment variables should be provided by the environment. Doing this with APPLICATION_DEFAULT_CREDENTIALS means that your code always sets this value when it should only do this when the code is running off Google Cloud.
For completeness, if you need to create Credentials from a JSON string rather than from a file contain a JSON string, you can use from_service_account_info (see google.oauth2.service_account)

Related

How does client= translate.TranslationServiceClient() work in conjunction with os.environ['GOOGLE_APPLICATION_CREDENTIALS']

I am using python and azure function app to send a document to be translated using the google cloud translation api.
I am trying to load the credentials from a tempfile (json) using the below code. The idea is to later download the json file from blob storage and store it in a temp file but I am not thinking about the blob storage for now.
key= {cred info}
f= tempfile.NamedTemporaryFile(suffix='.json', mode='a+')
json.dump(key, f)
f.flush()
f.seek(0)
os.environ['GOOGLE_APPLICATION_CREDENTIALS'] = f.name
client= translate.TranslationServiceClient()
But when I run this I get the following error:
Exception: PermissionError: [Errno 13] Permission denied:
How can I correctly load the creds from a temp file?. Also what is the relationship between translate.TranslationServiceClient() and os.environ['GOOGLE_APPLICATION_CREDENTIALS'] = f.name? Does the TranslationServiceClient() get the creds from the environment variable?
I have been looking at this problem for a while now and I cannot find a good solution. Any help would be amazing!
edit:
when I change it to
os.environ['GOOGLE_APPLICATION_CREDENTIALS'] = f.read()
I get a different error:
System.Private.CoreLib: Exception while executing function:
Functions.Trigger. System.Private.CoreLib: Result: Failure
Exception: DefaultCredentialsError:
EDIT 2:
Its really weird, but it works when I read the file just before like so:
contents= f.read()
os.environ['GOOGLE_APPLICATION_CREDENTIALS'] = f.name
client= translate.TranslationServiceClient()
Any ideas why?
Any application which connects to any GCP Product requires credentials to authenticate. Now there are many ways how this authentication works.
According to the Google doc
Additionally, we recommend you use Google Cloud Client Libraries for your application. Google Cloud Client Libraries use a library called Application Default Credentials (ADC) to automatically find your service account credentials. ADC looks for service account credentials in the following order:
If the environment variable GOOGLE_APPLICATION_CREDENTIALS is set, ADC uses the service account key or configuration file that the variable points to.
If the environment variable GOOGLE_APPLICATION_CREDENTIALS isn't set, ADC uses the service account that is attached to the resource that is running your code.
This service account might be a default service account provided by Compute Engine, Google Kubernetes Engine, App Engine, Cloud Run, or Cloud Functions. It might also be a user-managed service account that you created.
If ADC can't use any of the above credentials, an error occurs.
There are also modules provided by Google that can be used to pass the credentials.
If you already have the JSON value as dictionary then you can simply pass dictionary in from_service_account_info(key)
Example:
key = json.load(open("JSON File Path")) # loading my JSON file into dictionary
client = translate.TranslationServiceClient().from_service_account_info(key)
In your case you already have the key as dictionary
As for the error you are getting, I believe that has to be something with the temp file. Because GOOGLE_APPLICATION_CREDENTIALS needs full access to the JSON file path to read from it.

Using Secrets Manager to authenticate for Google API

I'm running a flask app that will access Bigquery on behalf of users using a service account they upload.
To store those service account credentials, I thought the following might be a good set up:
ENV Var: Stores my credentials for accessing google secrets manager
Secret & secret version: in google secrets manager for each user of the application. This will access the user's own bigquery instance on behalf of the user.
--
I'm still learning about secrets, but this seemed more appropriate than any way of storing credentials in my own database?
--
The google function for accessing secrets is:
def access_secret_version(secret_id, version_id=version_id):
# Create the Secret Manager client.
client = secretmanager.SecretManagerServiceClient()
# Build the resource name of the secret version.
name = f"projects/{project_id}/secrets/{secret_id}/versions/{version_id}"
# Access the secret version.
response = client.access_secret_version(name=name)
# Return the decoded payload.
return response.payload.data.decode('UTF-8')
However, this returns JSON as a string. When then using this for big query:
credentials = access_secret_version(secret_id, version_id=version_id)
BigQuery_client = bigquery.Client(credentials=json.dumps(credentials),
project=project_id)
I get the error:
File "/Users/Desktop/application_name/venv/lib/python3.8/site-
packages/google/cloud/client/__init__.py", line 167, in __init__
raise ValueError(_GOOGLE_AUTH_CREDENTIALS_HELP)
ValueError: This library only supports credentials from google-auth-library-python.
See https://google-auth.readthedocs.io/en/latest/ for help on authentication with
this library.
Locally I'm storing the credentials and accessing them via a env variable. But as I intend for this application to have multiple users, from different organisations I don't think that scales.
I think my question boils down to two pieces:
Is this a sensible method for storing and accessing credentials?
Can you authenticate to Bigquery using a string rather than a .json file indicated here

How to get Google OAUTH Token without using Gcloud Command Line

I am currently using the following code to get the OAUTH Token
command = 'gcloud auth print-access-token'
result = str(subprocess.Popen(command, universal_newlines=True, shell=True, stdout=subprocess.PIPE,
stderr=subprocess.PIPE).communicate())
The result variable has the OAUTH Token. This technique uses my current logged in gcloud config.
However, I am looking out for a way to get the OAUTH Token without using command line.
I am using this OAUTH Token to make CDAP calls to get the Google Dataflow Pipeline Execution Details.
I checked some google blogs. This is the one I think should try but it asks to create consent screen and it will require one time activity to provide consent to the scopes defined and then it should work.
Google Document
Shall I follow steps in above document and check OR is there any other way we can get the OAUTH Token?
Is there a way to get authentication done by service account instead of google user account and get the OAUTH Token?
For automated process, service account is the recommended way. You can use the google-oauth library for this. You can generate an access token like this
# With default credential (your user account or the Google Cloud Component service account.
# Or with the service account key file defined in the GOOGLE_APPLICATION_CREDENTIALS env var -> for platform outside GCP)
credentials, project_id = google.auth.default(scopes=["https://www.googleapis.com/auth/cloud-platform"])
# With service account key file (not recommended)
# credentials = service_account.Credentials.from_service_account_file('service-account.json',
# scopes=["https://www.googleapis.com/auth/cloud-platform"])
from google.auth.transport import requests
credentials.refresh(requests.Request())
print(credentials.token)
However, if you want to call Google cloud APIs, I recommend you to use authorized request object
Here an example of BigQuery call. You can use service account key file to generate your credential as in my previous example.
base_url = 'https://bigquery.googleapis.com'
credentials, project_id = google.auth.default(scopes=['https://www.googleapis.com/auth/cloud-platform'])
project_id = 'MyProjectId'
authed_session = AuthorizedSession(credentials)
response = authed_session.request('GET', f'{base_url}/bigquery/v2/projects/{project_id}/jobs')
print(response.json())
EDIT
When you want to use Google APIs, a service account key file is not needed (and I recommend you to not use it) on your computer and on GCP component. The Application Default Credential is always sufficient.
When you are in your local environment, you must run the command gcloud auth application-default login. With this command, you will register your personal account as default credential when you run locally your app. (of course, you need to have your user account email authorized on the component that you call)
When you are on GCP environment, each component have a default service account (or you can specify one with you configure your component). Thanks to the component "identity", you can use the default credential. (of course, you need to have the service account email authorized on the component that you call)
ONLY when you run an app automatically and outside GCP, you need a service account key file (for example, in your CI/CD other that Cloud Build, or in an app deployed on other Cloud Provider or on premise)
Why service account key file is not recommended? It's at least my recommendation because this file is ..... a file!! That's the problem. You have a way to authenticate a service account in a simple file: you have to store it securely (it's a secret and an authentication method!!), you can copy it, you can send it by email, you can even commit it in a public GIT repository... In addition, Google recommend to rotate them every 90 days, so it's a nightmare to rotate, to trace and to manage

How can I trigger an HTTP Cloud Function from within Google App Engine?

I have a Flask app in Google App Engine Standard Environment Python, and I also have a Cloud Function with an HTTP trigger which accepts a JSON body including the URL of a file. The CF downloads the file at that URL then saves it to a GCS bucket. The GAE service account has Cloud Function Invoker permissions, yet when using urlfetch.fetch() in my GAE code to trigger CF, the App Engine code gets a 403 Forbidden error unless I make the CF trigger callable by anyone.
How do I successfully call/trigger CF's from GAE in Python? I assume the answer is one of these:
Set IAM permissions on GAE service account to {enlighten me here}
Add authentication headers in urlfetch.fetch() like so {different enlightenment}
Make CF triggerable from anywhere, but hard code some secret key so the CF code itself handles authentication.
It's well documented here: Cloud Functions Authentication
In short you have to provide your service account credentials in the authentication header.
To get your credentials use the Google Auth Client library. If you are testing from local you should create a service account JSON and load it to the environment variable GOOGLE_APPLICATION_CREDENTIALS but on App Engine it will work from scratch.
After you have gotten your token, pass it as an auth header like so:
auth_req = google.auth.transport.requests.Request()
auth_token = google.oauth2.id_token.fetch_id_token(auth_req, cloud_function_url)
response = requests.post(cloud_function_url, json=payload, headers={"Authorization" : f"Bearer {auth_token}"})

Unauthorized error in GAE SDK, but it works once deployed

I am running this code in a small example:
from google.cloud import storage
from google.appengine.api import app_identity
class TestB(base_handler.TRNHandler):
#...
def post(self):
client = storage.Client()
bucket_name = os.environ.get('BUCKET_NAME',
app_identity.get_default_gcs_bucket_name())
bucket = client.get_bucket(bucket_name)
#...
If I deploy this code everything works as expected. But when I run it locally (SDK), I get an error: Unauthorized: 401 Invalid Credentials. What's happening and how can I fix it?
I've got a pretty strong guess, although I can't be sure without seeing your exact logs and whatnot.
The google.cloud library is smart about authorization. It uses a thing called "application default credentials." If you run that code on App Engine or on a GCE instance, the code will be able to figure out which service account is associated with that instance and authorize itself with the credentials of that account.
However, when you run the program locally, the library has no way of knowing which credentials to use, and so it just makes calls anonymously. Your bucket probably hasn't granted anonymous users access (which is good), and so the call fails with a 401.
You can, however, register credentials locally with the gcloud command:
$> gcloud auth application-default login
Run that, and the library will use whatever credentials you've used to log in for a while. Alternatively, you could also make sure that the environment variable GOOGLE_APPLICATION_CREDENTIALS points to a service account's JSON key file.
There's a bunch of documentation on exactly how Application Default Credentials pick a credential.
Alternately, if you'd prefer to specify auth right in the program, you can do that too:
storage = Storage.from_service_account_json('/path/to/key_file.json')

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