# Use the VM resource API that matches the scale set's orchestration mode

> Why does a scale-set management script need different instance-detail calls for Flexible and Uniform orchestration?

- Canonical URL: https://update.dsesecurity.com/updates/dse-20260909-184-use-the-vm-resource-api-that-matches-the-scale-set-s-orchestration-mode/
- Publisher: Detection Systems & Engineering (DSE Security)
- Author: DSE Security Editorial Team
- Published: 2026-09-10T00:28:52+00:00
- Modified: 2026-09-10T00:55:36+00:00
- Last reviewed by DSE: 2026-09-09
- Resource type: Guide
- DSE priority: Information
- Topics: IT, Networks & Infrastructure
- Reading time: 2 minutes

## What you need to know

Why does a scale-set management script need different instance-detail calls for Flexible and Uniform orchestration?

## Potentially affected

Automation that inventories or manages VM instances in Azure Flexible or Uniform scale sets.

## DSE recommendation

Branch instance-management automation by orchestration mode and test the resource type and returned detail, not just the scale-set name.

## Article

## Source facts

Flexible scale sets manage ordinary Azure VM resources; Uniform instances instead use the scale-set VM resource API. Microsoft recommends standard VM APIs for Flexible instance management. A Flexible scale-set VM listing provides member IDs, while standard VM retrieval supplies individual VM details. Its boot-diagnostics access likewise uses standard VM operations, not the scale-set VM boot-diagnostics API. Orchestration mode is selected at creation and is not an editable setting afterward. [Microsoft Learn](https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-orchestration-modes).

## Applicability

Review scripts that were written for Uniform instances before applying them to a Flexible deployment. Keep membership discovery separate from retrieving a particular machine’s model, status, or diagnostics. A matching scale-set name should not be the only input used to choose an operation.

## DSE recommendation

Branch instance-management automation by orchestration mode and test the resource type and returned detail, not just the scale-set name. Make that choice explicit in shared inventory and diagnostic functions. Preserve the returned VM resource ID as the handoff between membership enumeration and detailed inspection. Do not propose changing orchestration mode as a quick repair for an incompatible API call.

## Verification

Run the read-only workflow against a known instance in each supported mode. Confirm that the selected call returns that instance’s expected model and diagnostic information rather than only membership identifiers. Retain the request resource type, target ID, and response shape in the test evidence. Treat an empty or incomplete result as a failed compatibility test until its meaning is understood.

## Official references

[Microsoft Learn: Scale-set orchestration modes](https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-orchestration-modes). Source reviewed September 9, 2026.

## Primary reference

- Name: Orchestration modes for Virtual Machine Scale Sets in Azure - Azure Virtual Machine Scale Sets | Microsoft Learn
- Authority: Microsoft Learn
- URL: https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-orchestration-modes
- Source publication date: Not stated by the source

## Citation and use

Preferred citation: “Use the VM resource API that matches the scale set's orchestration mode,” DSE Security, https://update.dsesecurity.com/updates/dse-20260909-184-use-the-vm-resource-api-that-matches-the-scale-set-s-orchestration-mode/
Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/
Usage and citation policy: https://update.dsesecurity.com/usage/
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