Authentication error while uploading to Azure Blob Storage :

Question

Hello Team, I am trying to upload pdf to blob storage using Flask and React application. This is how my flask application looks like :

sas_token = 'sv=sastokenexample'
blob_client = BlobServiceClient(account_url=f"https://{AZURE_STORAGE_ACCOUNT}.blob.core.windows.net/${sas_token}")
blob_container = blob_client.get_container_client('upload-conainer')

@app.route('/upload_file', methods= ['GET','POST'])
def upload():
    if request.method == 'POST':
        file = request.files['file']
        filename = secure_filename(file.filename)
        try:
            blob_container.upload_blob(filename, file)
            return jsonify({"Success" : "Upload"})
            
        except Exception as e:
            logging.exception("Exception in /upload_file")
            return jsonify({"error": str(e)}), 202

I get the below error when the above code is deployed. I have generated the SAS token for blob as well as enable CORS. Not sure why this is happening.

{
    "error": "Server failed to authenticate the request. Please refer to the information in the www-authenticate header.\nRequestId:dddb127c-201e-004c-3fcd-a2201e000000\nTime:2023-06-19T16:46:42.6306933Z\nErrorCode:NoAuthenticationInformation\nContent: <?xml version=\"1.0\" encoding=\"utf-8\"?><Error><Code>NoAuthenticationInformation</Code><Message>Server failed to authenticate the request. Please refer to the information in the www-authenticate header.\nRequestId:dddb127c-201e-004c-3fcd-a2201e000000\nTime:2023-06-19T16:46:42.6306933Z</Message></Error>"
}

Answer 1

Hello

check the below code

Changes made:

1. Added necessary imports for Flask, secure_filename, BlobServiceClient, and logging.
2. Created a Flask app using Flask(__name__).
3. Changed the account URL construction by removing the $ before the sas_token.
4. Renamed the container name to 'upload-container'.
5. Added additional error handling for cases where no file is found or an empty filename is provided.
6. Modified the response status code for error responses to be 400 for client errors and 500 for server errors.
7. Added a check for if __name__ == '__main__': to run the Flask app.

Please make sure to replace <your_storage_account_name> with the actual name of your Azure Storage account before running the code.

Certainly! Here's the corrected code:

python
Copy code
from flask import Flask, request, jsonify
from werkzeug.utils import secure_filename
from azure.storage.blob import BlobServiceClient
import logging

app = Flask(__name__)

sas_token = 'sastokenexample'
AZURE_STORAGE_ACCOUNT = '<your_storage_account_name>'
blob_client = BlobServiceClient(account_url=f"https://{AZURE_STORAGE_ACCOUNT}.blob.core.windows.net/{sas_token}")
blob_container = blob_client.get_container_client('upload-container')

@app.route('/upload_file', methods=['POST'])
def upload():
    if 'file' not in request.files:
        return jsonify({"error": "No file found in the request"}), 400
    
    file = request.files['file']
    if file.filename == '':
        return jsonify({"error": "Empty filename"}), 400
    
    filename = secure_filename(file.filename)
    try:
        blob_container.upload_blob(name=filename, data=file)
        return jsonify({"Success": "Upload"})
    
    except Exception as e:
        logging.exception("Exception in /upload_file")
        return jsonify({"error": str(e)}), 500

if __name__ == '__main__':
    app.run()