What is the best hosting plan configuration for a custom Azure function app that requires dynamic resource allocation and billing based on executions?

The choice of a hosting plan configuration significantly impacts the performance and cost-effectiveness of an Azure function app. The Consumption plan is designed specifically for serverless applications, enabling dynamic scaling based on the number of requests or executions. This means that resources are allocated in real time according to demand; when there are no requests, there are no charges, making it highly economical for applications with variable workloads.

Using the Windows operating system within the Consumption plan leverages the benefits of serverless computing while also providing familiar environments for developers who may be accustomed to Windows-based services. This combination is particularly suited for applications that do not require constant hosting and where features like built-in auto-scaling and automatic updates are advantageous.

In contrast, other plans like the App Service plan—whether in B1 or S1 tiers—require a set amount of resources to be allocated, which leads to fixed billing regardless of actual usage. While Docker containers provide flexibility in deployment, they are often used in scenarios where more control over the app environment or hosting is necessary, which is not the primary need for a simple function app focused on dynamic execution and billing. Thus, the Consumption plan with the Windows operating system aligns best with the requirements for dynamic resource allocation and execution-based pricing.