Azure Functions Hosting Plans
Azure Functions offers different hosting plans, each with distinct features, performance characteristics, and pricing models. Choosing the right hosting plan is crucial for optimizing your function app's cost and performance.
Consumption Plan
The Consumption plan is the default and most cost-effective option for many scenarios. It provides a fully managed environment where you only pay for the compute time your functions consume. When your functions aren't running, you don't incur any costs.
- Pay-per-execution: You are billed for the number of executions and the time your code runs.
- Automatic scaling: The platform automatically scales the number of instances based on the incoming event load.
- Cold starts: When a function hasn't been invoked for a while, it may experience a "cold start" delay as the instance needs to be provisioned.
- Best for: Event-driven workloads, intermittent tasks, and development/testing.
Premium Plan
The Premium plan offers more predictable performance and additional enterprise-grade features compared to the Consumption plan. It provides pre-warmed instances to minimize cold starts and offers VNet connectivity.
- Pre-warmed instances: Keep a configurable number of instances warm and ready to respond immediately, eliminating cold starts.
- VNet connectivity: Securely connect your function app to your virtual network.
- No execution limits: Functions can run for longer durations.
- More powerful hardware: Access to more powerful virtual machine instances.
- Higher compute costs: You pay for the pre-warmed instances even if they are not actively executing code, in addition to execution time.
- Best for: Production workloads requiring low latency, predictable performance, and VNet integration.
Dedicated (App Service) Plan
The Dedicated plan allows you to run your Azure Functions on the same infrastructure as your Azure App Service web apps. You can select the instance size and scale count, giving you full control over the underlying compute resources.
- Fixed monthly cost: You pay a fixed price based on the configured App Service plan tier and instance count.
- No cold starts: Instances are always running.
- Predictable performance: Dedicated resources ensure consistent performance.
- Full control: Manage the underlying VMs and scale manually or with auto-scaling rules.
- Less cost-effective for sporadic workloads: Can be more expensive if your functions are not constantly in use.
- Best for: Long-running tasks, predictable high-traffic scenarios, or when you want to consolidate App Service and Functions workloads on the same plan.
Choosing the Right Plan
Consider your application's latency requirements, expected traffic patterns, integration needs (like VNet), and budget when selecting a hosting plan. The Consumption plan is a great starting point, while the Premium and Dedicated plans offer greater control and predictable performance for production scenarios.
Key Differences Summary
| Feature | Consumption Plan | Premium Plan | Dedicated Plan |
|---|---|---|---|
| Cost Model | Pay-per-execution | Pre-warmed instances + execution | Fixed monthly cost (App Service Plan) |
| Cold Starts | Possible | Eliminated (with pre-warming) | Eliminated |
| VNet Connectivity | No | Yes | Yes (if App Service plan supports it) |
| Scaling | Automatic | Automatic + Pre-warming | Manual or Auto-scale rules |
For more detailed information and specific pricing, please refer to the Azure Functions Pricing page.