DeepGanguly explains the migration from Azure Functions V1 to V2 on Azure Container Apps, highlighting technical improvements, resource model benefits, and a step-by-step guide for deploying serverless functions in container environments.

Transition to Azure Functions V2 on Azure Container Apps

Introduction

Azure Functions on Azure Container Apps now support two deployment models: V1 (Legacy Microsoft.Web RP Model) and the recommended V2 (Microsoft.App RP Model). V2 offers a native, feature-rich experience for hosting serverless workloads as containers on Azure.

V1 Limitations

Troubleshooting Restrictions

  • No direct container access or real-time log viewing.
  • Console and live output are restricted; diagnostics are indirect via Log Analytics and Application Insights.

Portal and Management Experience

  • Missing features: multi-revision, easy auth, health probes, custom domains.

DAPR Integration Challenges

  • .NET isolated functions may encounter compatibility issues with DAPR during builds due to dependency conflicts.

Functions V2: Improved Model

Functions V2 leverages the Microsoft.App RP for direct container app creation with kind=functionapp:

  • Resource consolidation: Eliminates proxy Function App resources for simplified management.
  • Native features: Multi-revision traffic splitting, seamless authentication, private endpoints, metrics, alerting, CI/CD integrations (Azure Pipelines, GitHub Actions), health probes, custom domains, secrets management, and sidecar containers.
  • No code changes needed: Existing function container images work with V2.

Feature Enhancements

Unsupported Legacy Deployment Approach

Deploying function images as plain container apps (without kind=functionapp) via Microsoft.App RP is no longer advised:

  • Not officially supported.
  • No autoscale; scaling must be configured manually.
  • Lacks key V2 features down the roadmap (e.g., listing functions, function keys).

Recommendation: Migrate to V2 for maximum native Azure Container Apps support.

Migration Checklist: V1 to V2

1. Preparation

  • Identify if currently running Functions V1 (Web RP) in Azure Container Apps.
  • Retrieve your parent function container image.
  • Record all configurations: environment variables, secrets, storage connections, networking settings.
  • Review quotas (memory, CPU, instance limits) in Azure Container Apps; adjust as needed.

2. Create V2 Container App

  • In Azure Portal, select “Optimize for Functions app” or use CLI (az functionapp create) to deploy your image.
  • No code rebuild required — reuse your function container image.
  • Apply all configuration/environment variables from your previous deployment.
  • For detailed instructions, visit Functions on Container Apps V2 documentation.

3. Validation

  • Test function triggers (HTTP, Event Hub, Service Bus, etc.).
  • Validate all integrations with databases, storage, and other Azure services.

4. DNS and Custom Domains

  • V2 app has a new DNS name.
  • Update DNS records and rebinding SSL/TLS certificates.
  • Notify stakeholders about DNS and endpoint changes; verify traffic routing and endpoints.

5. Cutover

  • Switch production traffic to V2.
  • Monitor closely for errors or scaling issues.
  • Communicate with users and team about the transition.

6. Cleanup

  • Remove old V1 deployment.
  • Update project/team documentation with details and lessons learned.

Feedback & Support

Updated: Oct 14, 2025

Author

DeepGanguly

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