Azure Functions

Overview

Azure Functions is Microsoft Azure's function-as-a-service offering that provides a serverless execution environment for your code. Azure Functions are commonly used to:

• Extend Astra DB with additional data processing capabilities, such as aggregating, summarizing and validating data periodically;
• Connect Astra DB with other cloud services into data pipelines that move, process and analyze data.

Prerequisites

• You should have an Astra account
• You should Create an Astra Database
• You should Have an Astra Token
• You should Download your Secure Connect Bundle

Using Python Driver

✅ 1. Create a function.

1. Follow the Quickstart to create a Python function in Azure from the command line using the v1 Python programming model and Azure CLI. Complete all the steps to successfully deploy and test the function in Azure.

2. Use Azure CLI to add these runtime environment variables to the application settings:

   • ASTRA_DB_CLIENT_ID: A Client ID is generated together with an application token (see the Prerequisites section above).
   • ASTRA_DB_CLIENT_SECRET: A Client secret is generated together with an application token (see the Prerequisites section above).

     az functionapp config appsettings set --name <APP_NAME> --resource-group <RESOURCE_GROUP_NAME> --settings "ASTRA_DB_CLIENT_ID=Hdisr..."
     
     az functionapp config appsettings set --name <APP_NAME> --resource-group <RESOURCE_GROUP_NAME> --settings "ASTRA_DB_CLIENT_SECRET=UB3Tm8cR,Ic..."
     

     Note that <APP_NAME> and <RESOURCE_GROUP_NAME> must be replaced with correct application and resurce group names used in the previous step. Similarly, ASTRA_DB_CLIENT_ID and ASTRA_DB_CLIENT_SECRET must be assigned correct values generated for your database.

3. Copy the secure connect bundle file to the project directory. (See the Prerequisites section above if you need to download your secure connect bundle.)

4. Add cassandra-driver, a Python client library for Apache Cassandra, DataStax Astra DB and DataStax Enterprise, to the requirements.txt file:
   

5. Replace the __init__.py content with:

   from cassandra.cluster import Cluster
   from cassandra.auth import PlainTextAuthProvider
   import logging
   import azure.functions as func
   import os
   
   ASTRA_DB_CLIENT_ID = os.environ['ASTRA_DB_CLIENT_ID']
   ASTRA_DB_CLIENT_SECRET = os.environ['ASTRA_DB_CLIENT_SECRET']
   
   cloud_config= {
       'secure_connect_bundle': 'secure-connect-bundle-for-your-database.zip',
       'use_default_tempdir': True
   }
   auth_provider = PlainTextAuthProvider(ASTRA_DB_CLIENT_ID, ASTRA_DB_CLIENT_SECRET)
   cluster = Cluster(cloud=cloud_config, auth_provider=auth_provider, protocol_version=4)
   
   def main(req: func.HttpRequest) -> func.HttpResponse:    
   
       session = cluster.connect()
   
       row = session.execute("SELECT cql_version FROM system.local WHERE key = 'local';").one()
       cql_version = row[0]   
   
       logging.info(f"{cql_version} Success")
   
       return func.HttpResponse(f"{cql_version} Success")
   

   You can learn more about the code above by reading the python-driver documentation. Note that secure-connect-bundle-for-your-database.zip must be replaced with a correct file name for your secure connect bundle.

✅ 2. Deploy the function.

1. Use Astra CLI to deploy the updated function:

   func azure functionapp publish <APP_NAME>
   

2. On the Microsoft Azure portal, find the newly deployed function:
   

✅ 3. Test the function.

1. Under Developer, select Code + Test and then Test/Run. Locate the Run button:
   

2. Click Run and observe the output and logs:
   
   Notice the CQL version output 3.4.5 and status code 200.

Using Python SDK

✅ 1. Create a function.

1. Follow the Quickstart to create a Python function in Azure from the command line using the v1 Python programming model and Azure CLI. Complete all the steps to successfully deploy and test the function in Azure.

2. Use Azure CLI to add these runtime environment variables to the application settings:

   • ASTRA_DB_ID: A Database ID value can be found on the Astra DB dashboard.
   • ASTRA_DB_REGION: A Region name can be found on the overview page for a specific Astra DB database.
   • ASTRA_DB_APPLICATION_TOKEN: An Application Token can be generated for a specific Astra DB database (see the Prerequisites section above).

     az functionapp config appsettings set --name <APP_NAME> --resource-group <RESOURCE_GROUP_NAME> --settings "ASTRA_DB_ID=0c2f6f34-41ea-..."
     
     az functionapp config appsettings set --name <APP_NAME> --resource-group <RESOURCE_GROUP_NAME> --settings "ASTRA_DB_REGION=us-east1"
     
     az functionapp config appsettings set --name <APP_NAME> --resource-group <RESOURCE_GROUP_NAME> --settings "ASTRA_DB_APPLICATION_TOKEN=AstraCS:avDWzU..."
     

     Note that <APP_NAME> and <RESOURCE_GROUP_NAME> must be replaced with correct application and resurce group names used in the previous step. Similarly, ASTRA_DB_ID, ASTRA_DB_REGION and ASTRA_DB_APPLICATION_TOKEN must be assigned correct values associated with your database.

3. Add AstraPy, a Pythonic SDK for DataStax Astra and Stargate, to the requirements.txt file:
   

4. Replace the __init__.py content with:

   from astrapy.rest import create_client, http_methods
   import logging
   import azure.functions as func
   import os
   
   ASTRA_DB_ID = os.environ['ASTRA_DB_ID']
   ASTRA_DB_REGION = os.environ['ASTRA_DB_REGION']
   ASTRA_DB_APPLICATION_TOKEN = os.environ['ASTRA_DB_APPLICATION_TOKEN']
   
   astra_http_client = create_client(astra_database_id=ASTRA_DB_ID,
                                     astra_database_region=ASTRA_DB_REGION,
                                     astra_application_token=ASTRA_DB_APPLICATION_TOKEN)
   
   def main(req: func.HttpRequest) -> func.HttpResponse:    
   
       res = astra_http_client.request(
           method=http_methods.GET,
           path=f"/api/rest/v2/keyspaces/system/local/local"
       )
       cql_version = res["data"][0]['cql_version']   
   
       logging.info(f"{cql_version} Success")
   
       return func.HttpResponse(f"{cql_version} Success")
   

   You can learn more about the code above by reading the AstraPy documentation.

✅ 2. Deploy the function.

1. Use Astra CLI to deploy the updated function:

   func azure functionapp publish <APP_NAME>
   

2. On the Microsoft Azure portal, find the newly deployed function:
   

✅ 3. Test the function.

1. Under Developer, select Code + Test and then Test/Run. Locate the Run button:
   

2. Click Run and observe the output and logs:
   
   Notice the CQL version output 3.4.5 and status code 200.

---

Last update: 2023-02-17