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.
