Azure Functions runtime versions

Azure Functions supports different versions of the Functions runtime. Understanding these versions is crucial for managing your function apps, ensuring compatibility, and leveraging the latest features.

This document outlines the current supported runtime versions, how to check your function app's version, and how to update it.

Supported Runtime Versions

The Azure Functions runtime is comprised of two main components:

  • Functions Host: The core runtime that executes your function code.
  • Language Worker: A process that handles language-specific logic for runtimes like Node.js, Python, Java, etc.

Microsoft provides different versions of the Functions runtime. It's recommended to use the latest supported LTS (Long-Term Support) version for your production applications.

Current LTS and Latest Versions

As of the latest update, the primary supported versions are:

  • v4 (LTS): The latest Long-Term Support version. Recommended for most production workloads.
  • v3: Older LTS version, still supported but consider migrating to v4.

Newer versions are introduced periodically. Always refer to the Azure Functions Support Lifecycle for definitive end-of-support dates.

Checking Your Function App's Runtime Version

You can check the runtime version of your Azure Function App through the Azure portal:

  1. Navigate to your Function App in the Azure portal.
  2. In the left-hand menu, under the Settings section, select Configuration.
  3. Under the Function runtime settings tab, you will find the Runtime stack and Version.

Using Azure CLI

You can also check the version using the Azure CLI:

az functionapp show --name --resource-group --query "properties.functionAppVersion"

Replace <YourFunctionAppName> and <YourResourceGroupName> with your actual application and resource group names.

Updating Your Function App's Runtime Version

You can update the runtime version of your function app via the Azure portal or Azure CLI.

Updating in the Azure Portal

  1. Navigate to your Function App in the Azure portal.
  2. Go to Configuration > Function runtime settings.
  3. Select the desired version from the Version dropdown.
  4. Click Save. Your function app will restart with the new runtime version.

Updating using Azure CLI

To update to v4, for example:

az functionapp update --name --resource-group --runtime-version 4

Note: The specific parameters for updating might vary slightly based on the Azure CLI version and the target runtime.

Version Compatibility and Migration

When updating your runtime version, consider the following:

  • Language Worker Compatibility: Ensure your chosen language worker version is compatible with the Functions Host version.
  • Breaking Changes: Review the release notes for each runtime version for any breaking changes that might affect your existing code.
  • Testing: Always test your function apps thoroughly in a staging environment before updating production applications.

Deprecation Policy

Azure Functions runtime versions are deprecated and eventually retired according to a schedule. It's essential to stay informed about these timelines to plan your migrations effectively. Visit the Azure Functions Support Lifecycle page for the latest information.