Getting Started with Azure Functions

Alex Brown October 26, 2023

Azure Serverless Functions Development

Serverless computing is transforming how developers build and deploy applications. At the forefront of this revolution is Microsoft Azure Functions, a powerful and flexible platform that allows you to run small pieces of code, or "functions," without the need to manage infrastructure. This guide will walk you through the essential steps to get started with Azure Functions.

What are Azure Functions?

Azure Functions enable you to build event-driven applications on a managed platform. You write code in your preferred language (C#, JavaScript, TypeScript, Python, Java, PowerShell) and Azure handles the underlying infrastructure, scaling, and availability. You only pay for the resources consumed when your code is running.

Key Benefits:

Cost-Effective: Pay only for what you use with a consumption-based pricing model.
Scalability: Automatically scales based on demand.
Flexibility: Supports multiple programming languages.
Event-Driven: Trigger functions based on a wide range of events (HTTP requests, queue messages, database changes, timers, etc.).
Managed Infrastructure: Focus on writing code, not managing servers.

Setting Up Your Development Environment

Before you can create your first Azure Function, you'll need to set up your local development environment. The recommended approach is to use the Azure Functions Core Tools.

Prerequisites:

Node.js: Azure Functions Core Tools are built on Node.js. Download and install the latest LTS version from nodejs.org.
Azure Functions Core Tools: Install using npm:

npm install -g azure-functions-core-tools@4 --unsafe-perm true

Creating Your First Function Project

Let's create a simple HTTP-triggered function. Open your terminal or command prompt and navigate to the directory where you want to create your project. Then, run the following commands:

func init MyFunctionProject --worker-runtime dotnet --docker
cd MyFunctionProject
func new --name MyHttpTrigger --template "HTTP trigger" --authlevel "anonymous"

This will:

Initialize a new Azure Functions project in a folder named MyFunctionProject.
Specify the .NET runtime and enable Dockerfile generation.
Create a new function named MyHttpTrigger with an HTTP trigger template and anonymous authentication.

Understanding the Project Structure

After running the commands, your project directory will have a structure similar to this:

MyFunctionProject/
├── MyHttpTrigger/
│   ├── function.json
│   └── index.cs (or equivalent for your language)
├── host.json
├── local.settings.json
└── MyFunctionProject.csproj (or equivalent)

MyHttpTrigger/: Contains the code and configuration for your specific function.
function.json: Defines the function's bindings (triggers and inputs/outputs).
index.cs: The actual code for your function (replace with appropriate file extension for other runtimes).
host.json: Global configuration for the Azure Functions host.
local.settings.json: Stores local application settings and connection strings.
.csproj: Project file for .NET projects.

Running Your Function Locally

To test your function without deploying it to Azure, you can run it locally. Navigate to your project's root directory in the terminal and run:

func start

The output will show the URL where your HTTP-triggered function is running. Typically, it will be something like:

Http Functions:
    MyHttpTrigger: http://localhost:7071/api/MyHttpTrigger

You can now open this URL in your browser or use a tool like curl or Postman to send requests to your function. If you provided a query parameter like name, you can test it with:

curl "http://localhost:7071/api/MyHttpTrigger?name=Azure+User"

Deploying to Azure

Once you're satisfied with your function locally, you can deploy it to Azure. You'll need an Azure subscription and the Azure CLI installed.

Steps:

Log in to Azure:
```
az login
```

Create an Azure Resource Group:

az group create --name MyResourceGroup --location "East US"

Create an Azure Storage Account: Functions require a storage account.

az storage account create --name mystorageaccountunique --location "East US" --resource-group MyResourceGroup --sku Standard_LRS

(Replace mystorageaccountunique with a globally unique name)

Deploy your Function App:

func azure functionapp publish MyFunctionApp --storage-account mystorageaccountunique --resource-group MyResourceGroup

(Replace MyFunctionApp with a globally unique name for your Function App)

Note: The func azure functionapp publish command will prompt you for information like your subscription, resource group, and storage account if not already configured or if multiple exist. It's often easier to pre-configure these or use a deployment script.

Next Steps and Further Learning

Congratulations! You've successfully created and deployed your first Azure Function. From here, you can explore:

Different Triggers: Timer triggers, Blob storage triggers, Queue triggers, Cosmos DB triggers, and more.
Input and Output Bindings: Seamlessly integrate with other Azure services.
Durable Functions: Build stateful workflows and orchestrations.
Monitoring: Utilize Application Insights for detailed logging and performance monitoring.
CI/CD: Set up continuous integration and deployment pipelines.

Azure Functions offer a robust and scalable way to build modern cloud applications. Dive deeper into the official Azure Functions documentation to unlock its full potential.