Azure functions coding best practices with examples

Azure functions coding best practices with examples

Azure Functions is a serverless compute service that enables developers to build and deploy event-driven, serverless applications at scale. It provides a fully managed, platform-as-a-service (PaaS) environment for building and running microservices-based applications. To help developers build high-quality and scalable Azure Functions, here are some coding best practices to follow:

• Keep Functions Small and Focused

Each Azure Function should do one specific task and nothing else. Avoid creating a large function that performs multiple tasks, as it can make your code difficult to read, test, and maintain. Instead, break your code into smaller functions that perform individual tasks, and compose them to create more complex workflows.

For example, consider an e-commerce application that sends a confirmation email when a customer places an order. Instead of creating a single function that retrieves order details, composes an email, and sends it, break it into three smaller functions: one to retrieve order details, one to compose an email, and one to send the email.

• Use Dependency Injection

Azure Functions supports dependency injection (DI), which is a design pattern that enables you to decouple your code by injecting dependencies into functions. It makes your code more modular, testable, and easier to maintain. Use DI to inject dependencies such as database connections, services, and configurations.

For example, let's say you have a function that needs to access a database to retrieve data. Instead of creating a new database connection every time the function is called, use DI to inject the database connection as a dependency.

• Use Logging and Tracing

Logging and tracing are essential for troubleshooting and monitoring your Azure Functions. Use a logging framework such as Azure Application Insights to log events and exceptions. Use tracing to track the execution path of your functions.

For example, consider a function that retrieves data from a database. Use tracing to track the execution path of the function, such as when it connects to the database, retrieves data, and returns the result. Use logging to record any exceptions that occur during the execution of the function.

• Use Environment Variables

Use environment variables to store important information such as connection strings, API keys, and passwords. It enables you to change the configuration of your application without modifying your code.

For example, let's say you have a function that connects to a database. Instead of hard-coding the connection string in your code, use an environment variable to store it.

Note: You can store sensitive information in key-vault which is more secure and use in App Setting.

• Use Async/Await

Azure Functions supports asynchronous programming, which enables you to write code that doesn't block the execution of the function. Use the async/await keywords to write asynchronous code.

For example, consider a function that retrieves data from a database. Use async/await to perform the database query asynchronously, so the function can continue to execute while the query is running.

• Use Continuous Integration and Deployment

Use continuous integration and deployment (CI/CD) to automate the deployment of your Azure Functions. Use a CI/CD pipeline to build, test, and deploy your code to different environments.

For example, let's say you have a development, staging, and production environment. Use a CI/CD pipeline to build and test your code in the development environment, then deploy it to the staging environment for further testing, and finally deploy it to the production environment when it's ready.

• Use Appropriate Trigger Types

Choose the appropriate trigger type for your function based on the type of event you want to process. Azure Functions supports various trigger types, including HTTP triggers, blob storage triggers, Cosmos DB triggers, and more.

For example, if you want to process an HTTP request, use an HTTP trigger. If you want to process a file uploaded to a storage account, use a blob storage trigger.

• Use Appropriate Binding Types

Choose the appropriate binding type for your function based on the type of data you want to access. Azure Functions supports various binding types, including input bindings, output bindings, and trigger bindings.

For example, if you want to read data from a storage account, use an input binding. If you want to write data to a database, use an output binding.

• Use Durable Functions for Long-Running Workflows

Use Durable Functions to create long-running workflows that can span multiple function invocations. Durable Functions provides an extension to Azure Functions that enables you to write stateful workflows in a serverless environment.

For example, consider a workflow that involves multiple steps, such as processing an order, sending an email notification, and updating a database. Use Durable Functions to create a stateful workflow that can track the progress of each step and handle failures gracefully.

• Use Azure App Configuration 

Use Azure app configuration to manage the commonalty used App Setting by multiple function app . 

Use environment-specific configuration like Dev/Test/Prod etc.

For example, consider multiple function app that needs to access same database. Use a App configuration to store the database connection string, and use the appropriate configuration value relevant Azure functions such that if you need to update connection string the updating at one place will reflect in all function app.

• Use Unit Testing

Use unit testing to test the individual functions of your Azure Functions application. Write unit tests to ensure that each function behaves correctly and handles inputs and outputs as expected.

For example, write unit tests for each function to ensure that it returns the expected output given a particular input. Use a testing framework such as NUnit, xUnit, or MSTest to write and run unit tests.

These are some best practices for Azure Functions coding that can help you write high-quality, scalable, and maintainable applications.