Azure Functions on Azure Container Apps overview

Azure Functions provides integrated support for developing, deploying, and managing containerized function apps on Azure Container Apps. Use Azure Container Apps for your Functions apps when you need to run in the same environment as other microservices, APIs, websites, workflows, or any container hosted programs.

Container Apps hosting lets you run your functions in a fully supported and managed, container-based environment with built-in support for open-source monitoring, mTLS, Dapr, and Kubernetes Event-driven Autoscaling (KEDA).

As an integrated feature on Azure Container Apps, you can deploy Azure Functions images directly onto Azure Container Apps using the Microsoft.App resource provider by setting kind=functionapp when calling az containerapp create. Apps created this way have access to all Azure Container Apps features.

This article shows you how to create and deploy an Azure Functions app that runs within Azure Container Apps. You learn how to:

• Set up a containerized Functions app with preconfigured auto scaling rules
• Deploy your application using either the Azure portal or Azure CLI
• Verify your deployed function with an HTTP trigger

By running Functions in Container Apps, you benefit from automatic scaling, easy configuration, and a fully managed container environment—all without having to manage the underlying infrastructure yourself.

Scenarios

Azure Functions on Container Apps provide a versatile combination of services to meet the needs of your applications. The following scenarios are representative of the types of situations where paring Azure Container Apps with Azure Functions gives you the control and scaling features you need.

• Line-of-business APIs: Package custom libraries, packages, and APIs with Functions for line-of-business applications.

• Migration support: Migration of on-premises legacy and/or monolith applications to cloud native microservices on containers.

• Event-driven architecture: Supports event-driven applications for workloads already running on Azure Container Apps.

• Serverless workloads: Serverless workload processing of videos, images, transcripts, or any other processing intensive tasks that required GPU compute resources.

• Common Azure Functions scenarios: All common Azure Functions scenarios like processing file uploads, running scheduled tasks, responding to database changes, machine learning/AI and others detailed in Azure Functions scenarios.

Event-driven scaling

All Functions triggers are available in your containerized Functions app. However, only the following triggers can dynamically scale (from zero instances) based on received events when running in a Container Apps environment:

• Azure Event Grid
• Azure Event Hubs
• Azure Blob Storage (Event Grid based)
• Azure Queue Storage
• Azure Service Bus
• Durable Functions (MSSQL storage provider)
• HTTP
• Kafka
• Timer
• Azure Cosmos DB

Azure Functions on Container Apps are designed to configure the scale parameters and rules as per the event target. You don't need to worry about configuring the KEDA scaled objects. You can still set minimum and maximum replica count when creating or modifying your function app.

Auto scaling for Azure Cosmos DB trigger and Durable functions is currently supported using connection strings only.

You can write your function code in any language stack supported by Azure Functions. You can use the same Functions triggers and bindings with event-driven scaling.

Managed identity authorization

To adhere to security best practices, connect to remote services using Microsoft Entra authentication and managed identity authorization.

Managed identities are available for the following connections:

• Default storage account (AzureWebJobsStorage)
• Azure Container Registry: When running in Container Apps, you can use Microsoft Entra ID with managed identities for all binding extensions that support managed identities. Currently, only these binding extensions support event-driven scaling when using managed identity authentication:
• Azure Event Hubs
• Azure Queue Storage
• Azure Service Bus

For other bindings, use fixed replicas when using managed identity authentication. For more information, see the Functions developer guide.

Application logging

You can monitor your containerized function app hosted in Container Apps using Azure Monitor Application Insights in the same way you do with apps hosted by Azure Functions. For more information, see Monitor Azure Functions.

For bindings that support event-driven scaling, scale events are logged as FunctionsScalerInfo and FunctionsScalerError events in your Log Analytics workspace. For more information, see Application Logging in Azure Container Apps.

Next steps