Building a Serverless Function to Retrieve and Update a Resume Counter using Azure Functions and Cosmos DB

As a developer, you might have come across situations where you need to write a piece of code that is triggered in response to some external event. For example, you might want to create a service that listens for incoming HTTP requests and sends an email notification whenever a request is received. One way to achieve this is by using an Azure Function, which is a serverless compute service that allows you to run small pieces of code in response to events.

In this tutorial, we'll walk through the steps of creating an Azure Function with Cosmos DB integration using Python.

Prerequisites

Before we get started, make sure you have the following:

An Azure account with an active subscription.
The Azure Functions Core Tools are installed on your local machine.
Python 3.7 or later installed on your local machine.
A Cosmos DB account is set up in your Azure subscription.

Step 1: Create an Azure Function

The first step is to create an Azure Function that will be triggered in response to an HTTP request. To create an Azure Function, follow these steps:

Open a terminal or command prompt and run the following command to create a new Azure Function:
```
 func init MyFunction --python
```
This will create a new folder called MyFunction with the necessary files to create an Azure Function in Python.
Change directory into the new folder:
```
 cd MyFunction
```
Run the following command to create a new HTTP-triggered Azure Function:
```
 func new --name HttpTrigger --template "HTTP trigger"
```
This will create a new file called HttpTrigger/__init__.py with the necessary code to handle incoming HTTP requests.

Step 2: Set up Cosmos DB integration

The next step is to set up Cosmos DB integration in your Azure Function. To do this, we'll use the azure.cosmos package, which provides a Python SDK for interacting with Cosmos DB.

Install the azure.cosmos package by running the following command:
```
 pip install azure-cosmos
```

In the MyFunction directory, create a new file called local.settings.json with the following contents:

 {
   "IsEncrypted": false,
   "Values": {
     "AzureWebJobsStorage": "UseDevelopmentStorage=true",
     "FUNCTIONS_WORKER_RUNTIME": "python",
     "COSMOSDB_ENDPOINT": "<your Cosmos DB endpoint URI>",
     "COSMOSDB_KEY": "<your Cosmos DB access key>",
     "COSMOSDB_DATABASE_NAME": "<your Cosmos DB database name>",
     "COSMOSDB_CONTAINER_NAME": "<your Cosmos DB container name>"
   }
 }

Replace <your Cosmos DB endpoint URI>, <your Cosmos DB access key>, <your Cosmos DB database name>, and <your Cosmos DB container name> with the appropriate values for your Cosmos DB account.

In the MyFunction directory, open the HttpTrigger/__init__.py file and replace its contents with the following code:

 import logging
 import json
 import azure.functions as func
 import azure.cosmos.cosmos_client as cosmos_client
 import azure.cosmos.errors as errors

 def main(req: func.HttpRequest, counter: func.DocumentList) -> func.HttpResponse:

     logging.info('Python HTTP trigger function processed a request.')

     name = req.params.get('name')
     if not name:
         try:
             req_body = req.get_json()
         except ValueError:

Building a Serverless Function to Retrieve and Update a Resume Counter using Azure Functions and Cosmos DB

Creating an Azure Function with Cosmos DB integration in Python

Table of contents

Prerequisites

Step 1: Create an Azure Function

Step 2: Set up Cosmos DB integration