Azure Functions 101: What Is Azure Functions?

This is the first post in a series: Azure Functions 101. In this series, I will be covering the following topics:

• Part 1: What Is Azure Functions (this post)
• Part 2: Anatomy of Azure Functions (coming soon)
• Part 3: Deploying Azure Function Resources Using Bicep and GitHub Actions (coming soon)
• Part 4: Creating Azure Functions using the Azure Functions Core Tools (coming soon)
• Part 5: Publishing Azure Functions Using GitHub Actions (coming soon)

In this post, I will be introducing Azure Functions, its use cases, benefits, limitations, and pricing. I will also compare Azure Functions with other serverless offerings, such as Azure Logic Apps and Azure Container Apps.

Table of Contents

• What is Azure Functions?
• Use Cases
• Benefits
• Limitations
• Comparison with other serverless offerings
  • Azure Logic Apps
  • Azure Container Apps
  • Azure Container Instances
• Pricing
• Conclusion

What is Azure Functions?

Azure Functions is a serverless compute service that lets you run event-triggered code without the need to manage infrastructure. Azure Functions is a great solution for running small pieces of code in response to events, such as HTTP requests, file uploads, or messages from other Azure services. Azure Functions can be used to build microservices, event-driven applications, and more. It supports a variety of programming languages, including C#, Java, JavaScript, Python, and PowerShell.

Use Cases

Azure Functions has a wide range of use cases, including:

• Serverless APIs and microservices
• Scheduled tasks and cron jobs
• Data processing and ETL (Extract, Transform, Load)
• Webhooks and API integrations
• Real-time data processing
• Fan-out/fan-in scenarios
• Parallel processing

Benefits

Azure Functions has a number of benefits, including:

• Cost effective: Azure Functions is a pay-as-you-go service, meaning you only pay for the compute time you use.
• Scalable: Azure Functions can scale up and down automatically based on demand. This makes it a great solution for applications that have unpredictable usage patterns.
• Easy to integrate: Azure Functions can be integrated with a wide range of Azure services, including Azure Storage, Azure Cosmos DB, Azure Event Grid, Azure Service Bus, as well as many third-party services. This simplifies building complex applications and workflows.
• Easy to deploy: Azure Functions can be deployed using a variety of methods, including Visual Studio, Visual Studio Code, Azure DevOps, and GitHub Actions. This makes it easy to integrate Azure Functions into your existing development workflow.
• Multi-language support: Azure Functions supports a wide range of programming languages as stated above. This makes it easy to use the language you (or your team) are most comfortable with.
• No need to manage infrastructure: Azure Functions is a fully managed service, which means that you don’t have to worry about managing any infrastructure.

Limitations

Azure Functions has a few limitations, including:

• Cold-start: Azure Functions are hosted in a container that is only started when a request (or event) is received. This means that the first request to a function will take longer to execute than subsequent requests. This is known as a cold-start. This happens when using the Consumption plan. The Premium plan does not have this limitation as the container is always running.
• Limited execution time: The maximum execution time for a function is 10 minutes for the Consumption plan and 30 minutes for the Premium plan. This is not a limitation for most use cases, however, if you have long-running workflows, you may use Durable Functions.
• Vendor lock-in: Azure Functions is a proprietary service offered by Microsoft, which means that once you start using it, it can be challenging to switch to another provider. If you however containerize your functions, you can run them on any platform that supports Docker containers.
• Difficult to debug: Due to their distributed nature, Azure Functions can be difficult to debug.

Comparison with other serverless offerings

Azure Functions is not the only serverless compute service offered by Microsoft. There are a few other options, including Azure Logic Apps, Azure Container Apps, and Azure Container Instances, among others. In this section, I will compare Azure Functions with these other services.

Azure Logic Apps

Azure Logic Apps like Azure Functions, is a service that enables serverless workloads. Azure Functions is a serverless compute service, whereas Azure Logic Apps is a serverless workflow integration platform. Here are some of the differences between the two services:

• Functionality: Azure Functions are focused on executing small, stateless functions in response to an event trigger, such as a message on a queue or a change in a database. Logic Apps, on the other hand, are focused on orchestrating complex workflows that involve multiple actions and integrations across different services.
• Development experience: Azure functions have a code-first development experience (imperative programming), whereas Logic Apps have a declarative development experience (drag-and-drop) using a visual designer. This makes Logic Apps a great solution for non-developers.
• Integration: Azure Functions can be integrated to other services using triggers and bindings. Logic Apps can be integrated to other services using connectors. There are a wide range of connectors available for Logic Apps, including connectors for Azure services, and third-party services. You can also create custom connectors for Logic Apps. Currently there are more Logic Apps connectors available than Azure Functions bindings.
• Scalability: Both Azure Functions and Logic Apps can scale up and down automatically based on demand.

Azure Container Apps

Azure Container Apps is a fully managed environment that enables you to run containerized applications on a serverless platform. With Azure Container Apps, you don’t need to manage complex infrastructure such as Kubernetes clusters. While Azure Functions shares some characteristics with Azure Container Apps, it is specifically optimized for ephemeral functions deployed as either code or containers. Here are some of the differences between Azure Functions and Azure Container Apps:

• Functionality: Azure Functions are focused on executing small, stateless functions. Azure Container Apps, on the other hand, run any containerized application. If you can containerize it, you can run it on Azure Container Apps. Under the hood, Azure Container Apps uses Azure Kubernetes Service (AKS) to run your containerized applications.
• Support for long-running tasks: While Azure Functions can run long-running tasks (using Durable Functions), Azure Container Apps have much better support for long-running tasks.

Note: You can containerize your Azure Functions, which technically means you can run them on Azure Container Apps.

Azure Container Instances

Azure Container Instances (ACI) is a service that enables you to run containerized applications without having to manage any infrastructure. ACI is similar to Azure Container Apps, save for a few differences such as scalability and load balancing. The differences between Azure Functions and Azure Container Instances are similar to those between Azure Functions and Azure Container Apps. One other difference is that Azure Container Instances do not support auto-scaling. You have to manually spin up more instances when you need to scale up.

Pricing

Azure functions has three pricing plans:

• Consumption plan: The consumption plan is the default plan. It is a pay-as-you-go plan that charges you based on the number of executions and the amount of time your function runs. The consumption plan is a great solution for applications that have unpredictable usage patterns. The consumption plan has a few limitations, including a maximum execution time of 10 minutes and a cold-start. The consumption plan is free for the first 1 million executions per month. If you are not worried about the cold-start limitation, the consumption plan is the most cost-effective option.
• Premium plan: The premium plan is a good option when you want to avoid cold-starts. It allows you to define a minimum number of instances that will always be running. This means that the first request to a function will be executed immediately – no cold-start. It also gives you more performances as well as VNet integration. It’s a bit more pricy compared to the consumption plan.
• App service plan: This plan allows you to run your functions just like your web apps. If you are already using App Service to host your web apps, you can use the same App Service plan for your functions at no additional cost.

Conclusion

In this post I introduced Azure Functions, a serverless compute service offered by Microsoft. I discussed the uses cases for Azure Functions, as well as the benefits and limitations of the service. I also compared Azure Functions with other serverless offerings offered by Microsoft. I hope you found this post useful. If you have any questions or comments, please feel free to leave a comment below.