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Difficulty: MediumImplement Durable Functions

You are designing an Azure Durable Functions application to orchestrate a nightly data migration process. The workflow starts by retrieving a list of database tables and then fans out to run a migration activity function for each table in parallel. The activity function for each table performs heavy data transformations and can take up to 20 minutes to complete. The migration process must run securely, requiring the functions to access an Azure SQL Database via a private endpoint, which necessitates virtual network (VNet) integration. You need to select the most cost-effective Azure Functions hosting plan that supports both the execution time and the network requirements. Which Azure Functions hosting plan should you choose?

  1. Premium planAnswer
  2. B
    Consumption plan
  3. C
    Basic App Service plan
  4. D
    Standard App Service plan

Answer

The Premium plan is the most cost-effective hosting plan that meets the requirements.
The Premium plan is correct because it supports regional virtual network integration, allowing secure access to services via private endpoints. It also offers unbounded execution limits (guaranteed up to 30 minutes and configurable to run indefinitely), accommodating the 20-minute execution duration. Additionally, it supports dynamic scaling, which is ideal for handling the nightly parallel fan-out workload efficiently.

Step-by-Step Solution

1
Analyze the execution duration requirement.
The activity functions can take up to 20 minutes to complete. This rules out the Consumption plan, which has a maximum execution timeout of 10 minutes.
Azure Functions hosting plans have different execution duration limits.
2
Analyze the network isolation requirement.
The function must connect to an Azure SQL Database via a private endpoint, which requires regional VNet integration. This rules out both the Consumption plan and the Basic App Service plan.
VNet integration is only supported on Premium and Standard or higher App Service (Dedicated) plans.
3
Evaluate scaling and cost effectiveness for a nightly parallel workflow.
The workflow runs once a day (nightly) and requires rapid scale-out to process multiple migration tasks in parallel. The Premium plan scales out dynamically and only charges for resource usage during execution (with a minimum of one pre-warmed instance), making it more cost-effective and performant than a Dedicated plan which bills 24/7 and does not scale out as dynamically.
Comparing Premium and Dedicated plans for dynamic workloads.

Key Concept

Selecting the appropriate Azure Functions hosting plan based on execution limits, VNet integration requirements, scaling behaviors, and cost efficiency.
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Topics

Implement Durable Functions

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